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docs: Avoid using "firmware" in the documentation 

The term "firmware" is ambiguous - it could refer to the entire
project (host and micro-controller software) or to just the
micro-controller software.  Avoid the term in the documentation.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-04-27 15:14:11 -04:00
parent d7a1111955
commit c1c0b2dd38
8 changed files with 466 additions and 455 deletions
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6
docs/Code_Overview.md
View File

@ -17,7 +17,7 @@ host architectures. The build arranges for includes of
src/generic/somefile.h). src/generic/somefile.h).
The **klippy/** directory contains the C and Python source for the The **klippy/** directory contains the C and Python source for the
host part of the firmware. host part of the software.
The **lib/** directory contains external 3rd-party library code that The **lib/** directory contains external 3rd-party library code that
is necessary to build some targets. is necessary to build some targets.
@ -92,8 +92,8 @@ some functionality in C code.
Initial execution starts in **klippy/klippy.py**. This reads the Initial execution starts in **klippy/klippy.py**. This reads the
command-line arguments, opens the printer config file, instantiates command-line arguments, opens the printer config file, instantiates
the main printer objects, and starts the serial connection. The main the main printer objects, and starts the serial connection. The main
execution of gcode commands is in the process_commands() method in execution of G-code commands is in the process_commands() method in
**klippy/gcode.py**. This code translates the gcode commands into **klippy/gcode.py**. This code translates the G-code commands into
printer object calls, which frequently translate the actions to printer object calls, which frequently translate the actions to
commands to be executed on the micro-controller (as declared via the commands to be executed on the micro-controller (as declared via the
DECL_COMMAND macro in the micro-controller code). DECL_COMMAND macro in the micro-controller code).

32
docs/Debugging.md
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@ -1,17 +1,18 @@
The Klippy host code has some tools to help in debugging the firmware. The Klippy host code has some tools to help in debugging.
Translating gcode files to firmware commands Translating gcode files to micro-controller commands
============================================ ====================================================
The Klippy host code can run in a batch mode to produce the low-level The Klippy host code can run in a batch mode to produce the low-level
firmware commands associated with a gcode file. Inspecting these micro-controller commands associated with a gcode file. Inspecting
low-level firmware commands is useful when trying to understand the these low-level commands is useful when trying to understand the
actions of the low-level hardware. It can also be useful to compare actions of the low-level hardware. It can also be useful to compare
the difference in firmware commands after a code change. the difference in micro-controller commands after a code change.
To run Klippy in this batch mode, there is a one time step necessary To run Klippy in this batch mode, there is a one time step necessary
to generate the firmware "data dictionary". This is done by compiling to generate the micro-controller "data dictionary". This is done by
the firmware code to obtain the **out/klipper.dict** file: compiling the micro-controller code to obtain the **out/klipper.dict**
file:
``` ```
make menuconfig make menuconfig
@ -34,13 +35,13 @@ output. This output can be translated to readable text with:
``` ```
The resulting file **test.txt** contains a human readable list of The resulting file **test.txt** contains a human readable list of
firmware commands. micro-controller commands.
The batch mode disables certain response / request commands in order The batch mode disables certain response / request commands in order
to function. As a result, there will be some differences between to function. As a result, there will be some differences between
actual firmware commands and the above output. The generated data is actual commands and the above output. The generated data is useful for
useful for testing and inspection; it is not useful for sending to a testing and inspection; it is not useful for sending to a real
real micro-controller. micro-controller.
Testing with simulavr Testing with simulavr
===================== =====================
@ -74,9 +75,10 @@ cd /patch/to/klipper
make menuconfig make menuconfig
``` ```
and compile the firmware for an AVR atmega644p, disable the AVR and compile the micro-controller software for an AVR atmega644p,
watchdog timer, and set the MCU frequency to 20000000. Then one can disable the AVR watchdog timer, and set the MCU frequency
compile Klipper (run `make`) and then start the simulation with: to 20000000. Then one can compile Klipper (run `make`) and then start
the simulation with:
``` ```
PYTHONPATH=/path/to/simulavr/src/python/ ./scripts/avrsim.py -m atmega644 -s 20000000 -b 250000 out/klipper.elf PYTHONPATH=/path/to/simulavr/src/python/ ./scripts/avrsim.py -m atmega644 -s 20000000 -b 250000 out/klipper.elf

16
docs/Features.md
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@ -1,4 +1,4 @@
Klipper is a 3d printer firmware with several compelling features: Klipper has several compelling features:
* High precision stepper movement. Klipper utilizes an application * High precision stepper movement. Klipper utilizes an application
processor (such as a low-cost Raspberry Pi) when calculating printer processor (such as a low-cost Raspberry Pi) when calculating printer
@ -32,9 +32,9 @@ Klipper is a 3d printer firmware with several compelling features:
micro-controller architectures as well. micro-controller architectures as well.
* Simpler code. Klipper uses a very high level language (Python) for * Simpler code. Klipper uses a very high level language (Python) for
most code. The kinematics algorithms, the gcode parsing, the heating most code. The kinematics algorithms, the G-code parsing, the
and thermistor algorithms, etc. are all written in Python. This heating and thermistor algorithms, etc. are all written in
makes it easier to develop new functionality. Python. This makes it easier to develop new functionality.
* Advanced features: * Advanced features:
* Klipper implements the "pressure advance" algorithm for * Klipper implements the "pressure advance" algorithm for
@ -68,10 +68,10 @@ Klipper supports many standard 3d printer features:
gradually accelerate from standstill to cruising speed and then gradually accelerate from standstill to cruising speed and then
decelerate back to a standstill. decelerate back to a standstill.
* "Lookahead" support. The incoming stream of G-Code movement commands * "Look-ahead" support. The incoming stream of G-Code movement
are queued and analyzed - the acceleration between movements in a commands are queued and analyzed - the acceleration between
similar direction will be optimized to reduce print stalls and movements in a similar direction will be optimized to reduce print
improve overall print time. stalls and improve overall print time.
* Support for cartesian, delta, and corexy style printers. * Support for cartesian, delta, and corexy style printers.

290
docs/Firmware_Commands.md
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@ -1,290 +0,0 @@
This document provides high-level information on common firmware
commands. It is not an authoritative reference for these commands, nor
is it an exclusive list of all available firmware commands.
This document may be useful for users needing to configure a set of
hardware actions that their printer may require at startup (via the
"custom" field in the printer config file), and it may be useful for
developers wishing to obtain a high-level feel for available firmware
commands.
See the [protocol](Protocol.md) document for more information on the
format of commands and their low-level transmission. The commands here
are described using their "printf" style syntax - for those unfamiliar
with that format, just note that where a '%...' sequence is seen it
should be replaced with an actual integer. For example, a description
with "count=%c" could be replaced with the text "count=10".
Startup Commands
================
It may be necessary to take certain one-time actions to configure the
micro-controller and its peripherals. This section lists common
commands available for that purpose. Unlike other firmware commands,
these commands run as soon as they are received by the firmware and
they do not require any particular setup.
These commands are most useful in the "custom" block of the "mcu"
section of the printer configuration file. This feature is typically
used to configure the initial settings of LEDs, to configure
micro-stepping pins, to configure a digipot, etc.
Several of these commands will take a "pin=%u" parameter. The
low-level firmware uses integer encodings of the hardware pin numbers,
but to make things more readable the host will translate human
readable pin names (eg, "PA3") to their equivalent integer
encodings. By convention, any parameter named "pin" or that has a
"_pin" suffix will use pin name translation by the host. Similarly,
several commands take time parameters specified in clock ticks. One
can specify a value for these parameters in seconds using the
"TICKS()" macro - for example "cycle_ticks=TICKS(0.001)" would result
in "cycle_ticks=16000" on a micro-controller with a 16Mhz clock.
Common startup commands:
* `set_digital_out pin=%u value=%c` : This command immediately
configures the given pin as a digital out GPIO and it sets it to
either a low level (value=0) or a high level (value=1). This command
may be useful for configuring the initial value of LEDs and for
configuring the initial value of stepper driver micro-stepping pins.
* `set_pwm_out pin=%u cycle_ticks=%u value=%c` : This command will
immediately configure the given pin to use hardware based
pulse-width-modulation (PWM) with the given number of
cycle_ticks. The "cycle_ticks" is the number of MCU clock ticks each
power on and power off cycle should last. A cycle_ticks value of 1
can be used to request the fastest possible cycle time. The "value"
parameter is between 0 and 255 with 0 indicating a full off state
and 255 indicating a full on state. This command may be useful for
enabling CPU and nozzle cooling fans.
* `send_spi_message pin=%u msg=%*s` : This command can be used to
transmit messages to a serial-peripheral-interface (SPI) component
connected to the micro-controller. It has been used to configure the
startup settings of AD5206 digipots. The 'pin' parameter specifies
the chip select line to use during the transmission. The 'msg'
indicates the binary message to transmit to the given chip.
Firmware configuration
======================
Most commands in the firmware require an initial setup before they can
be successfully invoked. This section provides a high-level overview
of the micro-controller configuration process. This section and the
following sections are likely only of interest to developers
interested in the internal details of Klipper.
When the host first connects to the firmware it always starts by
obtaining the firmware's data dictionary (see [protocol](Protocol.md)
for more information). After the data dictionary is obtained the host
will check if the firmware is in a "configured" state and configure it
if not. Configuration involves the following phases:
* `get_config` : The host starts by checking if the firmware is already
configured. The firmware responds to this command with a "config"
response message. At micro-controller power-on the firmware always
starts in an unconfigured state. It remains in this state until the
host completes the configuration processes (by issuing a
finalize_config command). If the firmware is already configured (and
is configured with the desired settings) from a previous
host/firmware session then no further action is needed by the host
and the configuration process ends successfully.
* `allocate_oids count=%c` : This command is issued to inform the
firmware the maximum number of object-ids (oid) that the host
requires. It is only valid to issue this command once. An oid is an
integer identifier allocated to each stepper, each endstop, and each
schedulable gpio pin. The host determines in advance the number of
oids it will require to operate the hardware and passes this to the
firmware so that the firmware may allocate sufficient memory to
store a mapping from oid to internal firmware object.
* `config_XXX oid=%c ...` : By convention any command starting with
the "config_" prefix creates a new firmware object and assigns the
given oid to it. For example, the config_digital_out command will
configure the specified pin as a digital output GPIO and create an
internal object that the host can use to schedule changes to the
given GPIO. The oid parameter passed into the config command is
selected by the host and must be between zero and the maximum count
supplied in the allocate_oids command. The config commands may only
be run when the firmware is not in a configured state (ie, prior to
the host sending finalize_config) and after the allocate_oids
command has been sent.
* `finalize_config crc=%u` : The finalize_config command transitions
the firmware from an unconfigured state to a configured state. The
crc parameter passed to the firmware is stored in the firmware and
provided back to the host in "config" response messages. By
convention, the host takes a 32bit CRC of the firmware configuration
it will request and at the start of subsequent host/firmware
communication sessions it checks that the CRC stored in the firmware
exactly matches its desired CRC. If the CRC does not match then the
host knows the firmware has not been configured in the state desired
by the host.
Common firmware objects
-----------------------
This section lists some commonly used config commands.
* `config_digital_out oid=%c pin=%u default_value=%c
max_duration=%u` : This command creates an internal firmware object
for the given GPIO 'pin'. The pin will be configured in digital
output mode and set to an initial value as specified by
'default_value' (0 for low, 1 for high). Creating a digital_out
object allows the host to schedule GPIO updates for the given pin at
specified times (see the schedule_digital_out command described
below). Should the firmware go into shutdown mode then all
configured digital_out objects will be set back to their default
values. The 'max_duration' parameter is used to implement a safety
check - if it is non-zero then it is the maximum number of clock
ticks that the host may set the given GPIO to a non-default value
without further updates. For example, if the default_value is zero
and the max_duration is 16000 then if the host sets the gpio to a
value of one then it must schedule another update to the gpio pin
(to either zero or one) within 16000 clock ticks. This safety
feature can be used with heater pins to ensure the host does not set
the heater to a value of one and then go off-line.
* `config_pwm_out oid=%c pin=%u cycle_ticks=%u default_value=%c
max_duration=%u` : This command creates an internal object for
hardware based PWM pins that the host may schedule updates for. Its
usage is analogous to config_digital_out - see the description of
the 'set_pwm_out' and 'config_digital_out' commands for parameter
description.
* `config_soft_pwm_out oid=%c pin=%u cycle_ticks=%u default_value=%c
max_duration=%u` : This command creates an internal firmware object
for software implemented PWM. Unlike hardware pwm pins, a software
pwm object does not require any special hardware support (other than
the ability to configure the pin as a digital output GPIO). Because
the output switching is implemented in the software of the firmware,
it is recommended that the cycle_ticks parameter correspond to a
time of 10ms or greater. See the description of the 'set_pwm_out'
and 'config_digital_out' commands for parameter description.
* `config_analog_in oid=%c pin=%u` : This command is used to configure
a pin in analog input sampling mode. Once configured, the pin can be
sampled at regular interval using the query_analog_in command (see
below).
* `config_stepper oid=%c step_pin=%c dir_pin=%c min_stop_interval=%u
invert_step=%c` : This command creates an internal stepper
object. The 'step_pin' and 'dir_pin' parameters specify the step and
direction pins respectively; this command will configure them in
digital output mode. The 'invert_step' parameter specifies whether a
step occurs on a rising edge (invert_step=0) or falling edge
(invert_step=1). The 'min_stop_interval' implements a safety
feature - it is checked when the firmware finishes all moves for a
stepper - if it is non-zero it specifies the minimum number of clock
ticks since the last step. It is used as a check on the maximum
stepper velocity that a stepper may have before stopping.
* `config_end_stop oid=%c pin=%c pull_up=%c stepper_count=%c` : This
command creates an internal "endstop" object. It is used to specify
the endstop pins and to enable "homing" operations (see the
end_stop_home command below). The command will configure the
specified pin in digital input mode. The 'pull_up' parameter
determines whether hardware provided pullup resistors for the pin
(if available) will be enabled. The 'stepper_count' parameter
specifies the maximum number of steppers that this endstop may need
to halt during a homing operation (see end_stop_home below).
Common commands
===============
This section lists some commonly used run-time commands. It is likely
only of interest to developers looking to gain insight into Klippy.
* `schedule_digital_out oid=%c clock=%u value=%c` : This command will
schedule a change to a digital output GPIO pin at the given clock
time. To use this command a 'config_digital_out' command with the
same 'oid' parameter must have been issued during firmware
configuration.
* `schedule_pwm_out oid=%c clock=%u value=%c` : Schedules a change to
a hardware PWM output pin. See the 'schedule_digital_out' and
'config_pwm_out' commands for more info.
* `schedule_soft_pwm_out oid=%c clock=%u value=%c` : Schedules a
change to a software PWM output pin. See the 'schedule_digital_out'
and 'config_soft_pwm_out' commands for more info.
* `query_analog_in oid=%c clock=%u sample_ticks=%u sample_count=%c
rest_ticks=%u min_value=%hu max_value=%hu` : This command sets up a
recurring schedule of analog input samples. To use this command a
'config_analog_in' command with the same 'oid' parameter must have
been issued during firmware configuration. The samples will start as
of 'clock' time, it will report on the obtained value every
'rest_ticks' clock ticks, it will over-sample 'sample_count' number
of times, and it will pause 'sample_ticks' number of clock ticks
between over-sample samples. The 'min_value' and 'max_value'
parameters implement a safety feature - the firmware will verify the
sampled value (after any oversampling) is always between the
supplied range. This is intended for use with pins attached to
thermistors controlling heaters - it can be used to check that a
heater is within a temperature range.
* `get_status` : This command causes the firmware to generate a
"status" response message. The host sends this command once a second
to obtain the value of the micro-controller clock and to estimate
the drift between host and micro-controller clocks. It enables the
host to accurately estimate the micro-controller clock.
Stepper commands
----------------
* `queue_step oid=%c interval=%u count=%hu add=%hi` : This command
schedules 'count' number of steps for the given stepper, with
'interval' number of clock ticks between each step. The first step
will be 'interval' number of clock ticks since the last scheduled
step for the given stepper. If 'add' is non-zero then the interval
will be adjusted by 'add' amount after each step. This command
appends the given interval/count/add sequence to a per-stepper
queue. There may be hundreds of these sequences queued during normal
operation. New sequence are appended to the end of the queue and as
each sequence completes its 'count' number of steps it is popped
from the front of the queue. This system allows the firmware to
queue potentially hundreds of thousands of steps - all with reliable
and predictable schedule times.
* `set_next_step_dir oid=%c dir=%c` : This command specifies the value
of the dir_pin that the next queue_step command will use.
* `reset_step_clock oid=%c clock=%u` : Normally, step timing is
relative to the last step for a given stepper. This command resets
the clock so that the next step is relative to the supplied 'clock'
time. The host usually only sends this command at the start of a
print.
* `stepper_get_position oid=%c` : This command causes the firmware to
generate a "stepper_position" response message with the stepper's
current position. The position is the total number of steps
generated with dir=1 minus the total number of steps generated with
dir=0.
* `end_stop_home oid=%c clock=%u rest_ticks=%u pin_value=%c` : This
command is used during stepper "homing" operations. To use this
command a 'config_end_stop' command with the same 'oid' parameter
must have been issued during firmware configuration. When invoked,
the firmware will sample the endstop pin every 'rest_ticks' clock
ticks and check if it has a value equal to 'pin_value'. If the value
matches then the movement queue for the associated stepper will be
cleared and the stepper will come to an immediate halt. The host
uses this command to implement homing - the host instructs the
endstop to sample for the endstop trigger and then it issues a
series of queue_step commands to the stepper to move it towards the
endstop. Once the stepper hits the endstop, the trigger will be
detected, the movement halted, and the host notified.
### Move queue
Each queue_step command utilizes an entry in the firmware "move
queue". The firmware allocates this queue when it receives the
"finalize_config" command, and it reports the number of available
queue entries in "config" response messages.
It is the responsibility of the host to ensure that there is available
space in the queue before sending a queue_step command. The host does
this by calculating when each queue_step command completes and
scheduling new queue_step commands accordingly.

294
docs/MCU_Commands.md Normal file
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@ -0,0 +1,294 @@
This document provides information on the low-level micro-controller
commands that are sent from the Klipper "host" software and processed
by the Klipper micro-controller software. This document is not an
authoritative reference for these commands, nor is it an exclusive
list of all available commands.
This document may be useful for users needing to configure a set of
hardware actions that their printer may require at startup (via the
"custom" field in the printer config file), and it may be useful for
developers wishing to obtain a high-level feel for low-level commands.
See the [protocol](Protocol.md) document for more information on the
format of commands and their transmission. The commands here are
described using their "printf" style syntax - for those unfamiliar
with that format, just note that where a '%...' sequence is seen it
should be replaced with an actual integer. For example, a description
with "count=%c" could be replaced with the text "count=10".
Startup Commands
================
It may be necessary to take certain one-time actions to configure the
micro-controller and its peripherals. This section lists common
commands available for that purpose. Unlike most micro-controller
commands, these commands run as soon as they are received and they do
not require any particular setup.
These commands are most useful in the "custom" block of the "mcu"
section of the printer configuration file. This feature is typically
used to configure the initial settings of LEDs, to configure
micro-stepping pins, to configure a digipot, etc.
Several of these commands will take a "pin=%u" parameter. The
low-level micro-controller software uses integer encodings of the
hardware pin numbers, but to make things more readable the host will
translate human readable pin names (eg, "PA3") to their equivalent
integer encodings. By convention, any parameter named "pin" or that
has a "_pin" suffix will use pin name translation by the
host. Similarly, several commands take time parameters specified in
clock ticks. One can specify a value for these parameters in seconds
using the "TICKS()" macro - for example "cycle_ticks=TICKS(0.001)"
would result in "cycle_ticks=16000" on a micro-controller with a 16Mhz
clock.
Common startup commands:
* `set_digital_out pin=%u value=%c` : This command immediately
configures the given pin as a digital out GPIO and it sets it to
either a low level (value=0) or a high level (value=1). This command
may be useful for configuring the initial value of LEDs and for
configuring the initial value of stepper driver micro-stepping pins.
* `set_pwm_out pin=%u cycle_ticks=%u value=%c` : This command will
immediately configure the given pin to use hardware based
pulse-width-modulation (PWM) with the given number of
cycle_ticks. The "cycle_ticks" is the number of MCU clock ticks each
power on and power off cycle should last. A cycle_ticks value of 1
can be used to request the fastest possible cycle time. The "value"
parameter is between 0 and 255 with 0 indicating a full off state
and 255 indicating a full on state. This command may be useful for
enabling CPU and nozzle cooling fans.
* `send_spi_message pin=%u msg=%*s` : This command can be used to
transmit messages to a serial-peripheral-interface (SPI) component
connected to the micro-controller. It has been used to configure the
startup settings of AD5206 digipots. The 'pin' parameter specifies
the chip select line to use during the transmission. The 'msg'
indicates the binary message to transmit to the given chip.
Low-level micro-controller configuration
========================================
Most commands in the micro-controller require an initial setup before
they can be successfully invoked. This section provides an overview of
the configuration process. This section and the following sections are
likely only of interest to developers interested in the internal
details of Klipper.
When the host first connects to the micro-controller it always starts
by obtaining a data dictionary (see [protocol](Protocol.md) for more
information). After the data dictionary is obtained the host will
check if the micro-controller is in a "configured" state and configure
it if not. Configuration involves the following phases:
* `get_config` : The host starts by checking if the micro-controller
is already configured. The micro-controller responds to this command
with a "config" response message. The micro-controller software
always starts in an unconfigured state at power-on. It remains in
this state until the host completes the configuration processes (by
issuing a finalize_config command). If the micro-controller is
already configured from a previous session (and is configured with
the desired settings) then no further action is needed by the host
and the configuration process ends successfully.
* `allocate_oids count=%c` : This command is issued to inform the
micro-controller of the maximum number of object-ids (oid) that the
host requires. It is only valid to issue this command once. An oid
is an integer identifier allocated to each stepper, each endstop,
and each schedulable gpio pin. The host determines in advance the
number of oids it will require to operate the hardware and passes
this to the micro-controller so that it may allocate sufficient
memory to store a mapping from oid to internal object.
* `config_XXX oid=%c ...` : By convention any command starting with
the "config_" prefix creates a new micro-controller object and
assigns the given oid to it. For example, the config_digital_out
command will configure the specified pin as a digital output GPIO
and create an internal object that the host can use to schedule
changes to the given GPIO. The oid parameter passed into the config
command is selected by the host and must be between zero and the
maximum count supplied in the allocate_oids command. The config
commands may only be run when the micro-controller is not in a
configured state (ie, prior to the host sending finalize_config) and
after the allocate_oids command has been sent.
* `finalize_config crc=%u` : The finalize_config command transitions
the micro-controller from an unconfigured state to a configured
state. The crc parameter passed to the micro-controller is stored
and provided back to the host in "config" response messages. By
convention, the host takes a 32bit CRC of the configuration it will
request and at the start of subsequent communication sessions it
checks that the CRC stored in the micro-controller exactly matches
its desired CRC. If the CRC does not match then the host knows the
micro-controller has not been configured in the state desired by the
host.
Common micro-controller objects
-------------------------------
This section lists some commonly used config commands.
* `config_digital_out oid=%c pin=%u default_value=%c
max_duration=%u` : This command creates an internal micro-controller
object for the given GPIO 'pin'. The pin will be configured in
digital output mode and set to an initial value as specified by
'default_value' (0 for low, 1 for high). Creating a digital_out
object allows the host to schedule GPIO updates for the given pin at
specified times (see the schedule_digital_out command described
below). Should the micro-controller software go into shutdown mode
then all configured digital_out objects will be set back to their
default values. The 'max_duration' parameter is used to implement a
safety check - if it is non-zero then it is the maximum number of
clock ticks that the host may set the given GPIO to a non-default
value without further updates. For example, if the default_value is
zero and the max_duration is 16000 then if the host sets the gpio to
a value of one then it must schedule another update to the gpio pin
(to either zero or one) within 16000 clock ticks. This safety
feature can be used with heater pins to ensure the host does not
enable the heater and then go off-line.
* `config_pwm_out oid=%c pin=%u cycle_ticks=%u default_value=%c
max_duration=%u` : This command creates an internal object for
hardware based PWM pins that the host may schedule updates for. Its
usage is analogous to config_digital_out - see the description of
the 'set_pwm_out' and 'config_digital_out' commands for parameter
description.
* `config_soft_pwm_out oid=%c pin=%u cycle_ticks=%u default_value=%c
max_duration=%u` : This command creates an internal micro-controller
object for software implemented PWM. Unlike hardware pwm pins, a
software pwm object does not require any special hardware support
(other than the ability to configure the pin as a digital output
GPIO). Because the output switching is implemented in the
micro-controller software, it is recommended that the cycle_ticks
parameter correspond to a time of 10ms or greater. See the
description of the 'set_pwm_out' and 'config_digital_out' commands
for parameter description.
* `config_analog_in oid=%c pin=%u` : This command is used to configure
a pin in analog input sampling mode. Once configured, the pin can be
sampled at regular interval using the query_analog_in command (see
below).
* `config_stepper oid=%c step_pin=%c dir_pin=%c min_stop_interval=%u
invert_step=%c` : This command creates an internal stepper
object. The 'step_pin' and 'dir_pin' parameters specify the step and
direction pins respectively; this command will configure them in
digital output mode. The 'invert_step' parameter specifies whether a
step occurs on a rising edge (invert_step=0) or falling edge
(invert_step=1). The 'min_stop_interval' implements a safety
feature - it is checked when the micro-controller finishes all moves
for a stepper - if it is non-zero it specifies the minimum number of
clock ticks since the last step. It is used as a check on the
maximum stepper velocity that a stepper may have before stopping.
* `config_end_stop oid=%c pin=%c pull_up=%c stepper_count=%c` : This
command creates an internal "endstop" object. It is used to specify
the endstop pins and to enable "homing" operations (see the
end_stop_home command below). The command will configure the
specified pin in digital input mode. The 'pull_up' parameter
determines whether hardware provided pullup resistors for the pin
(if available) will be enabled. The 'stepper_count' parameter
specifies the maximum number of steppers that this endstop may need
to halt during a homing operation (see end_stop_home below).
Common commands
===============
This section lists some commonly used run-time commands. It is likely
only of interest to developers looking to gain insight into Klipper.
* `schedule_digital_out oid=%c clock=%u value=%c` : This command will
schedule a change to a digital output GPIO pin at the given clock
time. To use this command a 'config_digital_out' command with the
same 'oid' parameter must have been issued during micro-controller
configuration.
* `schedule_pwm_out oid=%c clock=%u value=%c` : Schedules a change to
a hardware PWM output pin. See the 'schedule_digital_out' and
'config_pwm_out' commands for more info.
* `schedule_soft_pwm_out oid=%c clock=%u value=%c` : Schedules a
change to a software PWM output pin. See the 'schedule_digital_out'
and 'config_soft_pwm_out' commands for more info.
* `query_analog_in oid=%c clock=%u sample_ticks=%u sample_count=%c
rest_ticks=%u min_value=%hu max_value=%hu` : This command sets up a
recurring schedule of analog input samples. To use this command a
'config_analog_in' command with the same 'oid' parameter must have
been issued during micro-controller configuration. The samples will
start as of 'clock' time, it will report on the obtained value every
'rest_ticks' clock ticks, it will over-sample 'sample_count' number
of times, and it will pause 'sample_ticks' number of clock ticks
between over-sample samples. The 'min_value' and 'max_value'
parameters implement a safety feature - the micro-controller
software will verify the sampled value (after any oversampling) is
always between the supplied range. This is intended for use with
pins attached to thermistors controlling heaters - it can be used to
check that a heater is within a temperature range.
* `get_status` : This command causes the micro-controller to generate
a "status" response message. The host sends this command once a
second to obtain the value of the micro-controller clock and to
estimate the drift between host and micro-controller clocks. It
enables the host to accurately estimate the micro-controller clock.
Stepper commands
----------------
* `queue_step oid=%c interval=%u count=%hu add=%hi` : This command
schedules 'count' number of steps for the given stepper, with
'interval' number of clock ticks between each step. The first step
will be 'interval' number of clock ticks since the last scheduled
step for the given stepper. If 'add' is non-zero then the interval
will be adjusted by 'add' amount after each step. This command
appends the given interval/count/add sequence to a per-stepper
queue. There may be hundreds of these sequences queued during normal
operation. New sequence are appended to the end of the queue and as
each sequence completes its 'count' number of steps it is popped
from the front of the queue. This system allows the micro-controller
to queue potentially hundreds of thousands of steps - all with
reliable and predictable schedule times.
* `set_next_step_dir oid=%c dir=%c` : This command specifies the value
of the dir_pin that the next queue_step command will use.
* `reset_step_clock oid=%c clock=%u` : Normally, step timing is
relative to the last step for a given stepper. This command resets
the clock so that the next step is relative to the supplied 'clock'
time. The host usually only sends this command at the start of a
print.
* `stepper_get_position oid=%c` : This command causes the
micro-controller to generate a "stepper_position" response message
with the stepper's current position. The position is the total
number of steps generated with dir=1 minus the total number of steps
generated with dir=0.
* `end_stop_home oid=%c clock=%u rest_ticks=%u pin_value=%c` : This
command is used during stepper "homing" operations. To use this
command a 'config_end_stop' command with the same 'oid' parameter
must have been issued during micro-controller configuration. When
this command is invoked, the micro-controller will sample the
endstop pin every 'rest_ticks' clock ticks and check if it has a
value equal to 'pin_value'. If the value matches then the movement
queue for the associated stepper will be cleared and the stepper
will come to an immediate halt. The host uses this command to
implement homing - the host instructs the endstop to sample for the
endstop trigger and then it issues a series of queue_step commands
to move a stepper towards the endstop. Once the stepper hits the
endstop, the trigger will be detected, the movement halted, and the
host notified.
### Move queue
Each queue_step command utilizes an entry in the micro-controller
"move queue". This queue is allocated when it receives the
"finalize_config" command, and it reports the number of available
queue entries in "config" response messages.
It is the responsibility of the host to ensure that there is available
space in the queue before sending a queue_step command. The host does
this by calculating when each queue_step command completes and
scheduling new queue_step commands accordingly.

6
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@ -15,9 +15,9 @@ See [code overview](Code_Overview.md) for information on the structure
and layout of the Klipper code. and layout of the Klipper code.
See [protocol](Protocol.md) for information on the messaging protocol See [protocol](Protocol.md) for information on the messaging protocol
between host and firmware. See also between host and micro-controller. See also
[firmware commands](Firmware_Commands.md) for a high-level description [MCU commands](MCU_Commands.md) for a description of low-level
of common commands implemented in the firmware. commands implemented in the micro-controller software.
See [debugging](Debugging.md) for information on how to test and debug See [debugging](Debugging.md) for information on how to test and debug
Klipper. Klipper.

256
docs/Protocol.md
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@ -1,8 +1,9 @@
The Klipper transmission protocol can be thought of, at a high level, The Klipper messaging protocol is used for low-level communication
as a series of command and response strings that are compressed, between the Klipper host software and the Klipper micro-controller
transmitted over a serial line, and then processed at the receiving software. At a high level the protocol can be thought of as a series
side. An example series of commands in uncompressed human-readable of command and response strings that are compressed, transmitted, and
format might look like: then processed at the receiving side. An example series of commands in
uncompressed human-readable format might look like:
``` ```
set_digital_out pin=86 value=1 set_digital_out pin=86 value=1
@ -12,34 +13,35 @@ queue_step oid=7 interval=7458 count=10 add=331
queue_step oid=7 interval=11717 count=4 add=1281 queue_step oid=7 interval=11717 count=4 add=1281
``` ```
See the [firmware commands](Firmware_Commands.md) document for See the [mcu commands](MCU_Commands.md) document for information on
information on available commands. See the [debugging](Debugging.md) available commands. See the [debugging](Debugging.md) document for
document for information on how to translate a G-Code file into its information on how to translate a G-Code file into its corresponding
corresponding human-readable firmware commands. human-readable micro-controller commands.
This page provides a high-level description of the Klipper This page provides a high-level description of the Klipper messaging
transmission protocol itself. It describes how messages are declared, protocol itself. It describes how messages are declared, encoded in
encoded in binary format (the "compression" scheme), and transmitted. binary format (the "compression" scheme), and transmitted.
The goal of the protocol is to enable an error-free communication The goal of the protocol is to enable an error-free communication
channel between the host and firmware that is low-latency, channel between the host and micro-controller that is low-latency,
low-bandwidth, and low-complexity for the firmware. low-bandwidth, and low-complexity for the micro-controller.
Firmware Interface Micro-controller Interface
================== ==========================
The Klipper transmission protocol can be thought of as a The Klipper transmission protocol can be thought of as a
[RPC](https://en.wikipedia.org/wiki/Remote_procedure_call) mechanism [RPC](https://en.wikipedia.org/wiki/Remote_procedure_call) mechanism
between firmware and host. The firmware declares the commands that the between micro-controller and host. The micro-controller software
host may invoke along with the response messages that it can declares the commands that the host may invoke along with the response
generate. The host uses that information to command the firmware to messages that it can generate. The host uses that information to
perform actions and to interpret the results. command the micro-controller to perform actions and to interpret the
results.
Declaring commands Declaring commands
------------------ ------------------
The firmware declares a "command" by using the DECL_COMMAND() macro in The micro-controller software declares a "command" by using the
the C code. For example: DECL_COMMAND() macro in the C code. For example:
``` ```
DECL_COMMAND(command_set_digital_out, "set_digital_out pin=%u value=%c"); DECL_COMMAND(command_set_digital_out, "set_digital_out pin=%u value=%c");
@ -48,11 +50,11 @@ DECL_COMMAND(command_set_digital_out, "set_digital_out pin=%u value=%c");
The above declares a command named "set_digital_out". This allows the The above declares a command named "set_digital_out". This allows the
host to "invoke" this command which would cause the host to "invoke" this command which would cause the
command_set_digital_out() C function to be executed in the command_set_digital_out() C function to be executed in the
firmware. The above also indicates that the command takes two integer micro-controller. The above also indicates that the command takes two
parameters. When the command_set_digital_out() C code is executed, it integer parameters. When the command_set_digital_out() C code is
will be passed an array containing these two integers - the first executed, it will be passed an array containing these two integers -
corresponding to the 'pin' and the second corresponding to the the first corresponding to the 'pin' and the second corresponding to
'value'. the 'value'.
In general, the parameters are described with printf() style syntax In general, the parameters are described with printf() style syntax
(eg, "%u"). The formatting directly corresponds to the human-readable (eg, "%u"). The formatting directly corresponds to the human-readable
@ -63,42 +65,42 @@ documentation. In this example, the "%c" is also used as documentation
to indicate the expected integer is 1 byte in size (the declared to indicate the expected integer is 1 byte in size (the declared
integer size does not impact the parsing or encoding). integer size does not impact the parsing or encoding).
At firmware compile time, the build will collect all commands declared The micro-controller build will collect all commands declared with
with DECL_COMMAND(), determine their parameters, and arrange for them DECL_COMMAND(), determine their parameters, and arrange for them to be
to be callable. callable.
Declaring responses Declaring responses
------------------- -------------------
To send information from the firmware to the host a "response" is To send information from the micro-controller to the host a "response"
generated. These are both declared and transmitted using the sendf() C is generated. These are both declared and transmitted using the
macro. For example: sendf() C macro. For example:
``` ```
sendf("status clock=%u status=%c", sched_read_time(), sched_is_shutdown()); sendf("status clock=%u status=%c", sched_read_time(), sched_is_shutdown());
``` ```
The above transmits a "status" response message that contains two The above transmits a "status" response message that contains two
integer parameters ("clock" and "status"). At firmware compile time integer parameters ("clock" and "status"). The micro-controller build
the build automatically finds all sendf() calls and generates encoders automatically finds all sendf() calls and generates encoders for
for them. The first parameter of the sendf() function describes the them. The first parameter of the sendf() function describes the
response and it is in the same format as command declarations. response and it is in the same format as command declarations.
The host can arrange to register a callback function for each The host can arrange to register a callback function for each
response. So, in effect, commands allow the host to invoke C functions response. So, in effect, commands allow the host to invoke C functions
in the firmware and responses allow the firmware to invoke code in the in the micro-controller and responses allow the micro-controller
host. software to invoke code in the host.
The firmware should only invoke sendf() from command or task handlers, The sendf() macro should only be invoked from command or task
and it should not be invoked from interrupts or timers. The firmware handlers, and it should not be invoked from interrupts or timers. The
does not need to issue a sendf() in response to a received command, it code does not need to issue a sendf() in response to a received
is not limited in the number of times sendf() may be invoked, and it command, it is not limited in the number of times sendf() may be
may invoke sendf() at any time from a task handler. invoked, and it may invoke sendf() at any time from a task handler.
### Output responses ### Output responses
To simplify debugging, the firmware also has an output() C To simplify debugging, there is also has an output() C function. For
function. For example: example:
``` ```
output("The value of %u is %s with size %u.", x, buf, buf_len); output("The value of %u is %s with size %u.", x, buf, buf_len);
@ -110,15 +112,14 @@ to generate and format arbitrary messages for human consumption.
Declaring constants Declaring constants
------------------- -------------------
The firmware can also define constants to be exported. For example, Constants can also be exported. For example, the following:
the following:
``` ```
DECL_CONSTANT(SERIAL_BAUD, 250000); DECL_CONSTANT(SERIAL_BAUD, 250000);
``` ```
would export a constant named "SERIAL_BAUD" with a value of 250000 would export a constant named "SERIAL_BAUD" with a value of 250000
from the firmware to the host. from the micro-controller to the host.
Low-level message encoding Low-level message encoding
========================== ==========================
@ -130,9 +131,9 @@ the transmission system.
Message Blocks Message Blocks
-------------- --------------
All data sent from host to firmware and vice-versa are contained in All data sent from host to micro-controller and vice-versa are
"message blocks". A message block has a two byte header and a three contained in "message blocks". A message block has a two byte header
byte trailer. The format of a message block is: and a three byte trailer. The format of a message block is:
``` ```
<1 byte length><1 byte sequence><n-byte content><2 byte crc><1 byte sync> <1 byte length><1 byte sequence><n-byte content><2 byte crc><1 byte sync>
@ -160,11 +161,11 @@ present in the message block content.
Message Block Contents Message Block Contents
---------------------- ----------------------
Each message block sent from host to firmware contains a series of Each message block sent from host to micro-controller contains a
zero or more message commands in its contents. Each command starts series of zero or more message commands in its contents. Each command
with a [Variable Length Quantity](#variable-length-quantities) (VLQ) starts with a [Variable Length Quantity](#variable-length-quantities)
encoded integer command-id followed by zero or more VLQ parameters for (VLQ) encoded integer command-id followed by zero or more VLQ
the given command. parameters for the given command.
As an example, the following four commands might be placed in a single As an example, the following four commands might be placed in a single
message block: message block:
@ -183,21 +184,22 @@ and encoded into the following eight VLQ integers:
``` ```
In order to encode and parse the message contents, both the host and In order to encode and parse the message contents, both the host and
firmware must agree on the command ids and the number of parameters micro-controller must agree on the command ids and the number of
each command has. So, in the above example, both the host and firmware parameters each command has. So, in the above example, both the host
would know that "id_set_digital_out" is always followed by two and micro-controller would know that "id_set_digital_out" is always
parameters, and "id_get_config" and "id_get_status" have zero followed by two parameters, and "id_get_config" and "id_get_status"
parameters. The host and firmware share a "data dictionary" that maps have zero parameters. The host and micro-controller share a "data
the command descriptions (eg, "set_digital_out pin=%u value=%c") to dictionary" that maps the command descriptions (eg, "set_digital_out
their integer command-ids. When processing the data, the parser will pin=%u value=%c") to their integer command-ids. When processing the
know to expect a specific number of VLQ encoded parameters following a data, the parser will know to expect a specific number of VLQ encoded
given command id. parameters following a given command id.
The message contents for blocks sent from firmware to host follow the The message contents for blocks sent from micro-controller to host
same format. The identifiers in these messages are "response ids", but follow the same format. The identifiers in these messages are
they serve the same purpose and follow the same encoding rules. In "response ids", but they serve the same purpose and follow the same
practice, message blocks sent from the firmware to the host never encoding rules. In practice, message blocks sent from the
contain more than one response in the message block contents. micro-controller to the host never contain more than one response in
the message block contents.
### Variable Length Quantities ### Variable Length Quantities
@ -229,60 +231,62 @@ the length as a VLQ encoded integer followed by the contents itself:
``` ```
The command descriptions found in the data dictionary allow both the The command descriptions found in the data dictionary allow both the
host and firmware to know which command parameters use simple VLQ host and micro-controller to know which command parameters use simple
encoding and which parameters use string encoding. VLQ encoding and which parameters use string encoding.
Data Dictionary Data Dictionary
=============== ===============
In order for meaningful communications to be established between In order for meaningful communications to be established between
firmware and host, both sides must agree on a "data dictionary". This micro-controller and host, both sides must agree on a "data
data dictionary contains the integer identifiers for commands and dictionary". This data dictionary contains the integer identifiers for
responses along with their descriptions. commands and responses along with their descriptions.
At compile time the firmware build uses the contents of DECL_COMMAND() The micro-controller build uses the contents of DECL_COMMAND() and
and sendf() macros to generate the data dictionary. The build sendf() macros to generate the data dictionary. The build
automatically assigns unique identifiers to each command and automatically assigns unique identifiers to each command and
response. This system allows both the host and firmware code to response. This system allows both the host and micro-controller code
seamlessly use descriptive human-readable names while still using to seamlessly use descriptive human-readable names while still using
minimal bandwidth. minimal bandwidth.
The host queries the data dictionary when it first connects to the The host queries the data dictionary when it first connects to the
firmware. Once the host downloads the data dictionary from the micro-controller. Once the host downloads the data dictionary from the
firmware, it uses that data dictionary to encode all commands and to micro-controller, it uses that data dictionary to encode all commands
parse all responses from the firmware. The host must therefore handle and to parse all responses from the micro-controller. The host must
a dynamic data dictionary. However, to keep the firmware simple, the therefore handle a dynamic data dictionary. However, to keep the
firmware always uses its static (compiled in) data dictionary. micro-controller software simple, the micro-controller always uses its
static (compiled in) data dictionary.
The data dictionary is queried by sending "identify" commands to the The data dictionary is queried by sending "identify" commands to the
firmware. The firmware will respond to each identify command with an micro-controller. The micro-controller will respond to each identify
"identify_response" message. Since these two commands are needed prior command with an "identify_response" message. Since these two commands
to obtaining the data dictionary, their integer ids and parameter are needed prior to obtaining the data dictionary, their integer ids
types are hard-coded in both the firmware and the host. The and parameter types are hard-coded in both the micro-controller and
"identify_response" response id is 0, the "identify" command id the host. The "identify_response" response id is 0, the "identify"
is 1. Other than having hard-coded ids the identify command and its command id is 1. Other than having hard-coded ids the identify command
response are declared and transmitted the same way as other commands and its response are declared and transmitted the same way as other
and responses. No other command or response is hard-coded. commands and responses. No other command or response is hard-coded.
The format of the transmitted data dictionary itself is a zlib The format of the transmitted data dictionary itself is a zlib
compressed JSON string. The firmware compile process generates the compressed JSON string. The micro-controller build process generates
string, compresses it, and stores it in the text section of the the string, compresses it, and stores it in the text section of the
firmware. The data dictionary can be much larger than the maximum micro-controller flash. The data dictionary can be much larger than
message block size - the host downloads it by sending multiple the maximum message block size - the host downloads it by sending
identify commands requesting progressive chunks of the data multiple identify commands requesting progressive chunks of the data
dictionary. Once all chunks are obtained the host will assemble the dictionary. Once all chunks are obtained the host will assemble the
chunks, uncompress the data, and parse the contents. chunks, uncompress the data, and parse the contents.
In addition to information on the communication protocol, the data In addition to information on the communication protocol, the data
dictionary also contains firmware version, constants (as defined by dictionary also contains the software version, constants (as defined
DECL_CONSTANT), and static strings. by DECL_CONSTANT), and static strings.
Static Strings Static Strings
-------------- --------------
To reduce bandwidth the data dictionary also contains a set of static To reduce bandwidth the data dictionary also contains a set of static
strings known to the firmware. This is useful when sending messages strings known to the micro-controller. This is useful when sending
from firmware to host. For example, if the firmware were to run: messages from micro-controller to host. For example, if the
micro-controller were to run:
``` ```
shutdown("Unable to handle command"); shutdown("Unable to handle command");
@ -295,22 +299,22 @@ to their associated human-readable strings.
Message flow Message flow
============ ============
Message commands sent from host to firmware are intended to be Message commands sent from host to micro-controller are intended to be
error-free. The firmware will check the CRC and sequence numbers in error-free. The micro-controller will check the CRC and sequence
each message block to ensure the commands are accurate and numbers in each message block to ensure the commands are accurate and
in-order. The firmware always processes message blocks in-order - in-order. The micro-controller always processes message blocks
should it receive a block out-of-order it will discard it and any in-order - should it receive a block out-of-order it will discard it
other out-of-order blocks until it receives blocks with the correct and any other out-of-order blocks until it receives blocks with the
sequencing. correct sequencing.
The low-level host code implements an automatic retransmission system The low-level host code implements an automatic retransmission system
for lost and corrupt message blocks sent to the firmware. To for lost and corrupt message blocks sent to the micro-controller. To
facilitate this, the firmware transmits an "ack message block" after facilitate this, the micro-controller transmits an "ack message block"
each successfully received message block. The host schedules a timeout after each successfully received message block. The host schedules a
after sending each block and it will retransmit should the timeout timeout after sending each block and it will retransmit should the
expire without receiving a corresponding "ack". In addition, if the timeout expire without receiving a corresponding "ack". In addition,
firmware detects a corrupt or out-of-order block it may transmit a if the micro-controller detects a corrupt or out-of-order block it may
"nak message block" to facilitate fast retransmission. transmit a "nak message block" to facilitate fast retransmission.
An "ack" is a message block with empty content (ie, a 5 byte message An "ack" is a message block with empty content (ie, a 5 byte message
block) and a sequence number greater than the last received host block) and a sequence number greater than the last received host
@ -325,15 +329,15 @@ in the event of transmission latency. The timeout, retransmit,
windowing, and ack mechanism are inspired by similar mechanisms in windowing, and ack mechanism are inspired by similar mechanisms in
[TCP](https://en.wikipedia.org/wiki/Transmission_Control_Protocol). [TCP](https://en.wikipedia.org/wiki/Transmission_Control_Protocol).
In the other direction, message blocks sent from firmware to host are In the other direction, message blocks sent from micro-controller to
designed to be error-free, but they do not have assured host are designed to be error-free, but they do not have assured
transmission. (Responses should not be corrupt, but they may go transmission. (Responses should not be corrupt, but they may go
missing.) This is done to keep the implementation in the firmware missing.) This is done to keep the implementation in the
simple. There is no automatic retransmission system for responses - micro-controller simple. There is no automatic retransmission system
the high-level code is expected to be capable of handling an for responses - the high-level code is expected to be capable of
occasional missing response (usually by re-requesting the content or handling an occasional missing response (usually by re-requesting the
setting up a recurring schedule of response transmission). The content or setting up a recurring schedule of response
sequence number field in message blocks sent to the host is always one transmission). The sequence number field in message blocks sent to the
greater than the last received sequence number of message blocks host is always one greater than the last received sequence number of
received from the host. It is not used to track sequences of response message blocks received from the host. It is not used to track
message blocks. sequences of response message blocks.

21
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@ -31,12 +31,12 @@ Host user interaction
Safety features Safety features
=============== ===============
* Support loading a valid step range into the firmware after * Support loading a valid step range into the micro-controller
homing. This would provide a sanity check in the firmware that would software after homing. This would provide a sanity check in the
reduce the risk of the host commanding a stepper motor past its micro-controller that would reduce the risk of the host commanding a
valid step range. To maintain high efficiency in the firmware, the stepper motor past its valid step range. To maintain high
firmware would only need to check periodically (eg, every 100ms) efficiency, the micro-controller would only need to check
that the stepper is in range. periodically (eg, every 100ms) that the stepper is in range.
* Possibly support periodically querying the endstop switches and use * Possibly support periodically querying the endstop switches and use
multiple step ranges depending on the switch state. This would multiple step ranges depending on the switch state. This would
@ -52,9 +52,10 @@ Testing features
================ ================
* Complete the host based simulator. It's possible to compile the * Complete the host based simulator. It's possible to compile the
firmware for a "host simulator", but that simulator doesn't do micro-controller for a "host simulator", but that simulator doesn't
anything currently. It would be useful to expand the code to support do anything currently. It would be useful to expand the code to
more error checks, kinematic simulations, and improved logging. support more error checks, kinematic simulations, and improved
logging.
Documentation Documentation
============= =============
@ -67,7 +68,7 @@ Documentation
Hardware features Hardware features
================= =================
* Port firmware to more architectures: * Port to additional micro-controller architectures:
* Beagle Bone Black PRU * Beagle Bone Black PRU
* Smoothieboard / NXP LPC1769 (ARM cortex-M3) * Smoothieboard / NXP LPC1769 (ARM cortex-M3)
* Unix based scheduling; Unix based real-time scheduling * Unix based scheduling; Unix based real-time scheduling