docs: Add FAQ item on AVR watchdog restart failures

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
This commit is contained in:
Kevin O'Connor 2017-12-11 18:15:59 -05:00
parent 319221ee23
commit 8944e2104d
1 changed files with 15 additions and 0 deletions

View File

@ -124,3 +124,18 @@ rates, but the stepper motor may not have sufficient torque to move at
a higher speed. So, for a Z axis with a very precise step_distance the
actual obtainable max_z_velocity may be smaller than what is
configured in Marlin.
### When I set "restart_method=command" my AVR device just hangs on a restart
Some old versions of the AVR bootloader have a known bug in watchdog
event handling. This typically manifests when the printer.cfg file has
restart_method set to "command". When the bug occurs, the AVR device
will be unresponsive until power is removed and reapplied to the
device (the power or status LEDs may also blink repeatedly until the
power is removed).
The workaround is to use a restart_method other than "command" or to
flash an updated bootloader to the AVR devices. Flashing a new
bootloader is a one time step that typically requires an external
programmer - search the web to find the instructions for your
particular device.