diff --git a/lib/README b/lib/README
index 00f888e2..ff6c1f7a 100644
--- a/lib/README
+++ b/lib/README
@@ -1,12 +1,5 @@
 This directory contains external library code.
 
-The pjrc_usb_serial directory contains code from:
-  http://www.pjrc.com/teensy/usb_serial.html
-version 1.7 (extracted on 20160605). It has been modified to compile
-on recent versions of gcc, to support asynchronous notification of
-incoming data, and to not use SOF interrupts. See usb_serial.patch for
-the modifications.
-
 The cmsis directory contains code from:
   https://github.com/ARM-software/CMSIS_5
 version 5.3.0 (49ac527aa7406cecbba46d4d3bdbc7f60c6c6d42). Contents
@@ -25,7 +18,7 @@ version 1.3.304 (extracted on 20180725). It has been modified to
 compile with gcc's LTO feature and to work with chips that have a
 bootloader. See samd21.patch for the modifications.
 
-The cmsis-sam4e8e directory contains code from the 
+The cmsis-sam4e8e directory contains code from the
 Atmel.SAM4E_DFP.1.1.57.atpack zip file found at:
   http://packs.download.atmel.com/
 version 1.1.57 (extracted on 20180806). It has been modified to compile
diff --git a/lib/pjrc_usb_serial/usb_serial.c b/lib/pjrc_usb_serial/usb_serial.c
deleted file mode 100644
index 0c2488d5..00000000
--- a/lib/pjrc_usb_serial/usb_serial.c
+++ /dev/null
@@ -1,947 +0,0 @@
-/* USB Serial Example for Teensy USB Development Board
- * http://www.pjrc.com/teensy/usb_serial.html
- * Copyright (c) 2008,2010,2011 PJRC.COM, LLC
- * 
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- * 
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- * 
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-// Version 1.0: Initial Release
-// Version 1.1: support Teensy++
-// Version 1.2: fixed usb_serial_available
-// Version 1.3: added transmit bandwidth test
-// Version 1.4: added usb_serial_write
-// Version 1.5: add support for Teensy 2.0
-// Version 1.6: fix zero length packet bug
-// Version 1.7: fix usb_serial_set_control
-
-#include <string.h>
-#define USB_SERIAL_PRIVATE_INCLUDE
-#include "usb_serial.h"
-
-
-/**************************************************************************
- *
- *  Configurable Options
- *
- **************************************************************************/
-
-// You can change these to give your code its own name.  On Windows,
-// these are only used before an INF file (driver install) is loaded.
-#define STR_MANUFACTURER	L"Your Name"
-#define STR_PRODUCT		L"USB Serial"
-
-// All USB serial devices are supposed to have a serial number
-// (according to Microsoft).  On windows, a new COM port is created
-// for every unique serial/vendor/product number combination.  If
-// you program 2 identical boards with 2 different serial numbers
-// and they are assigned COM7 and COM8, each will always get the
-// same COM port number because Windows remembers serial numbers.
-//
-// On Mac OS-X, a device file is created automatically which
-// incorperates the serial number, eg, /dev/cu-usbmodem12341
-//
-// Linux by default ignores the serial number, and creates device
-// files named /dev/ttyACM0, /dev/ttyACM1... in the order connected.
-// Udev rules (in /etc/udev/rules.d) can define persistent device
-// names linked to this serial number, as well as permissions, owner
-// and group settings.
-#define STR_SERIAL_NUMBER	L"12345"
-
-// Mac OS-X and Linux automatically load the correct drivers.  On
-// Windows, even though the driver is supplied by Microsoft, an
-// INF file is needed to load the driver.  These numbers need to
-// match the INF file.
-#define VENDOR_ID		0x16C0
-#define PRODUCT_ID		0x047A
-
-// When you write data, it goes into a USB endpoint buffer, which
-// is transmitted to the PC when it becomes full, or after a timeout
-// with no more writes.  Even if you write in exactly packet-size
-// increments, this timeout is used to send a "zero length packet"
-// that tells the PC no more data is expected and it should pass
-// any buffered data to the application that may be waiting.  If
-// you want data sent immediately, call usb_serial_flush_output().
-#define TRANSMIT_FLUSH_TIMEOUT	5   /* in milliseconds */
-
-// If the PC is connected but not "listening", this is the length
-// of time before usb_serial_getchar() returns with an error.  This
-// is roughly equivilant to a real UART simply transmitting the
-// bits on a wire where nobody is listening, except you get an error
-// code which you can ignore for serial-like discard of data, or
-// use to know your data wasn't sent.
-#define TRANSMIT_TIMEOUT	25   /* in milliseconds */
-
-// USB devices are supposed to implment a halt feature, which is
-// rarely (if ever) used.  If you comment this line out, the halt
-// code will be removed, saving 116 bytes of space (gcc 4.3.0).
-// This is not strictly USB compliant, but works with all major
-// operating systems.
-#define SUPPORT_ENDPOINT_HALT
-
-
-
-/**************************************************************************
- *
- *  Endpoint Buffer Configuration
- *
- **************************************************************************/
-
-// These buffer sizes are best for most applications, but perhaps if you
-// want more buffering on some endpoint at the expense of others, this
-// is where you can make such changes.  The AT90USB162 has only 176 bytes
-// of DPRAM (USB buffers) and only endpoints 3 & 4 can double buffer.
-
-#define ENDPOINT0_SIZE		16
-#define CDC_ACM_ENDPOINT	2
-#define CDC_RX_ENDPOINT		3
-#define CDC_TX_ENDPOINT		4
-#if defined(__AVR_AT90USB162__)
-#define CDC_ACM_SIZE		16
-#define CDC_ACM_BUFFER		EP_SINGLE_BUFFER
-#define CDC_RX_SIZE		32
-#define CDC_RX_BUFFER 		EP_DOUBLE_BUFFER
-#define CDC_TX_SIZE		32
-#define CDC_TX_BUFFER		EP_DOUBLE_BUFFER
-#else
-#define CDC_ACM_SIZE		16
-#define CDC_ACM_BUFFER		EP_SINGLE_BUFFER
-#define CDC_RX_SIZE		64
-#define CDC_RX_BUFFER 		EP_DOUBLE_BUFFER
-#define CDC_TX_SIZE		64
-#define CDC_TX_BUFFER		EP_DOUBLE_BUFFER
-#endif
-
-static const uint8_t PROGMEM endpoint_config_table[] = {
-	0,
-	1, EP_TYPE_INTERRUPT_IN,  EP_SIZE(CDC_ACM_SIZE) | CDC_ACM_BUFFER,
-	1, EP_TYPE_BULK_OUT,      EP_SIZE(CDC_RX_SIZE) | CDC_RX_BUFFER,
-	1, EP_TYPE_BULK_IN,       EP_SIZE(CDC_TX_SIZE) | CDC_TX_BUFFER
-};
-
-
-/**************************************************************************
- *
- *  Descriptor Data
- *
- **************************************************************************/
-
-// Descriptors are the data that your computer reads when it auto-detects
-// this USB device (called "enumeration" in USB lingo).  The most commonly
-// changed items are editable at the top of this file.  Changing things
-// in here should only be done by those who've read chapter 9 of the USB
-// spec and relevant portions of any USB class specifications!
-
-static const uint8_t PROGMEM device_descriptor[] = {
-	18,					// bLength
-	1,					// bDescriptorType
-	0x00, 0x02,				// bcdUSB
-	2,					// bDeviceClass
-	0,					// bDeviceSubClass
-	0,					// bDeviceProtocol
-	ENDPOINT0_SIZE,				// bMaxPacketSize0
-	LSB(VENDOR_ID), MSB(VENDOR_ID),		// idVendor
-	LSB(PRODUCT_ID), MSB(PRODUCT_ID),	// idProduct
-	0x00, 0x01,				// bcdDevice
-	1,					// iManufacturer
-	2,					// iProduct
-	3,					// iSerialNumber
-	1					// bNumConfigurations
-};
-
-#define CONFIG1_DESC_SIZE (9+9+5+5+4+5+7+9+7+7)
-static const uint8_t PROGMEM config1_descriptor[CONFIG1_DESC_SIZE] = {
-	// configuration descriptor, USB spec 9.6.3, page 264-266, Table 9-10
-	9, 					// bLength;
-	2,					// bDescriptorType;
-	LSB(CONFIG1_DESC_SIZE),			// wTotalLength
-	MSB(CONFIG1_DESC_SIZE),
-	2,					// bNumInterfaces
-	1,					// bConfigurationValue
-	0,					// iConfiguration
-	0xC0,					// bmAttributes
-	50,					// bMaxPower
-	// interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
-	9,					// bLength
-	4,					// bDescriptorType
-	0,					// bInterfaceNumber
-	0,					// bAlternateSetting
-	1,					// bNumEndpoints
-	0x02,					// bInterfaceClass
-	0x02,					// bInterfaceSubClass
-	0x01,					// bInterfaceProtocol
-	0,					// iInterface
-	// CDC Header Functional Descriptor, CDC Spec 5.2.3.1, Table 26
-	5,					// bFunctionLength
-	0x24,					// bDescriptorType
-	0x00,					// bDescriptorSubtype
-	0x10, 0x01,				// bcdCDC
-	// Call Management Functional Descriptor, CDC Spec 5.2.3.2, Table 27
-	5,					// bFunctionLength
-	0x24,					// bDescriptorType
-	0x01,					// bDescriptorSubtype
-	0x01,					// bmCapabilities
-	1,					// bDataInterface
-	// Abstract Control Management Functional Descriptor, CDC Spec 5.2.3.3, Table 28
-	4,					// bFunctionLength
-	0x24,					// bDescriptorType
-	0x02,					// bDescriptorSubtype
-	0x06,					// bmCapabilities
-	// Union Functional Descriptor, CDC Spec 5.2.3.8, Table 33
-	5,					// bFunctionLength
-	0x24,					// bDescriptorType
-	0x06,					// bDescriptorSubtype
-	0,					// bMasterInterface
-	1,					// bSlaveInterface0
-	// endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
-	7,					// bLength
-	5,					// bDescriptorType
-	CDC_ACM_ENDPOINT | 0x80,		// bEndpointAddress
-	0x03,					// bmAttributes (0x03=intr)
-	CDC_ACM_SIZE, 0,			// wMaxPacketSize
-	64,					// bInterval
-	// interface descriptor, USB spec 9.6.5, page 267-269, Table 9-12
-	9,					// bLength
-	4,					// bDescriptorType
-	1,					// bInterfaceNumber
-	0,					// bAlternateSetting
-	2,					// bNumEndpoints
-	0x0A,					// bInterfaceClass
-	0x00,					// bInterfaceSubClass
-	0x00,					// bInterfaceProtocol
-	0,					// iInterface
-	// endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
-	7,					// bLength
-	5,					// bDescriptorType
-	CDC_RX_ENDPOINT,			// bEndpointAddress
-	0x02,					// bmAttributes (0x02=bulk)
-	CDC_RX_SIZE, 0,				// wMaxPacketSize
-	0,					// bInterval
-	// endpoint descriptor, USB spec 9.6.6, page 269-271, Table 9-13
-	7,					// bLength
-	5,					// bDescriptorType
-	CDC_TX_ENDPOINT | 0x80,			// bEndpointAddress
-	0x02,					// bmAttributes (0x02=bulk)
-	CDC_TX_SIZE, 0,				// wMaxPacketSize
-	0					// bInterval
-};
-
-// If you're desperate for a little extra code memory, these strings
-// can be completely removed if iManufacturer, iProduct, iSerialNumber
-// in the device desciptor are changed to zeros.
-struct usb_string_descriptor_struct {
-	uint8_t bLength;
-	uint8_t bDescriptorType;
-	int16_t wString[];
-};
-static const struct usb_string_descriptor_struct PROGMEM string0 = {
-	4,
-	3,
-	{0x0409}
-};
-static const struct usb_string_descriptor_struct PROGMEM string1 = {
-	sizeof(STR_MANUFACTURER),
-	3,
-	STR_MANUFACTURER
-};
-static const struct usb_string_descriptor_struct PROGMEM string2 = {
-	sizeof(STR_PRODUCT),
-	3,
-	STR_PRODUCT
-};
-static const struct usb_string_descriptor_struct PROGMEM string3 = {
-	sizeof(STR_SERIAL_NUMBER),
-	3,
-	STR_SERIAL_NUMBER
-};
-
-// This table defines which descriptor data is sent for each specific
-// request from the host (in wValue and wIndex).
-static const struct descriptor_list_struct {
-	uint16_t	wValue;
-	uint16_t	wIndex;
-	const uint8_t	*addr;
-	uint8_t		length;
-} PROGMEM descriptor_list[] = {
-	{0x0100, 0x0000, device_descriptor, sizeof(device_descriptor)},
-	{0x0200, 0x0000, config1_descriptor, sizeof(config1_descriptor)},
-	{0x0300, 0x0000, (const uint8_t *)&string0, 4},
-	{0x0301, 0x0409, (const uint8_t *)&string1, sizeof(STR_MANUFACTURER)},
-	{0x0302, 0x0409, (const uint8_t *)&string2, sizeof(STR_PRODUCT)},
-	{0x0303, 0x0409, (const uint8_t *)&string3, sizeof(STR_SERIAL_NUMBER)}
-};
-#define NUM_DESC_LIST (sizeof(descriptor_list)/sizeof(struct descriptor_list_struct))
-
-
-/**************************************************************************
- *
- *  Variables - these are the only non-stack RAM usage
- *
- **************************************************************************/
-
-// zero when we are not configured, non-zero when enumerated
-static volatile uint8_t usb_configuration=0;
-
-// the time remaining before we transmit any partially full
-// packet, or send a zero length packet.
-static volatile uint8_t transmit_flush_timer=0;
-static uint8_t transmit_previous_timeout=0;
-
-// serial port settings (baud rate, control signals, etc) set
-// by the PC.  These are ignored, but kept in RAM.
-static uint8_t cdc_line_coding[7]={0x00, 0xE1, 0x00, 0x00, 0x00, 0x00, 0x08};
-static uint8_t cdc_line_rtsdtr=0;
-
-
-/**************************************************************************
- *
- *  Public Functions - these are the API intended for the user
- *
- **************************************************************************/
-
-// initialize USB serial
-void usb_init(void)
-{
-	HW_CONFIG();
-        USB_FREEZE();				// enable USB
-        PLL_CONFIG();				// config PLL, 16 MHz xtal
-        while (!(PLLCSR & (1<<PLOCK))) ;	// wait for PLL lock
-        USB_CONFIG();				// start USB clock
-        UDCON = 0;				// enable attach resistor
-	usb_configuration = 0;
-	cdc_line_rtsdtr = 0;
-        UDIEN = (1<<EORSTE);
-	sei();
-}
-
-// return 0 if the USB is not configured, or the configuration
-// number selected by the HOST
-uint8_t usb_configured(void)
-{
-	return usb_configuration;
-}
-
-// get the next character, or -1 if nothing received
-int16_t usb_serial_getchar(void)
-{
-	uint8_t c, intr_state;
-
-	// interrupts are disabled so these functions can be
-	// used from the main program or interrupt context,
-	// even both in the same program!
-	intr_state = SREG;
-	cli();
-	if (!usb_configuration) {
-		SREG = intr_state;
-		return -1;
-	}
-	UENUM = CDC_RX_ENDPOINT;
-	retry:
-	c = UEINTX;
-	if (!(c & (1<<RWAL))) {
-		// no data in buffer
-		if (c & (1<<RXOUTI)) {
-			UEINTX = 0x6B;
-			goto retry;
-		}	
-		UEIENX = (1<<RXOUTE);
-		SREG = intr_state;
-		return -1;
-	}
-	// take one byte out of the buffer
-	c = UEDATX;
-	// if buffer completely used, release it
-	if (!(UEINTX & (1<<RWAL))) UEINTX = 0x6B;
-	SREG = intr_state;
-	return c;
-}
-
-// number of bytes available in the receive buffer
-uint8_t usb_serial_available(void)
-{
-	uint8_t n=0, i, intr_state;
-
-	intr_state = SREG;
-	cli();
-	if (usb_configuration) {
-		UENUM = CDC_RX_ENDPOINT;
-		n = UEBCLX;
-		if (!n) {
-			i = UEINTX;
-			if (i & (1<<RXOUTI) && !(i & (1<<RWAL))) UEINTX = 0x6B;
-		}
-	}
-	SREG = intr_state;
-	return n;
-}
-
-// discard any buffered input
-void usb_serial_flush_input(void)
-{
-	uint8_t intr_state;
-
-	if (usb_configuration) {
-		intr_state = SREG;
-		cli();
-		UENUM = CDC_RX_ENDPOINT;
-		while ((UEINTX & (1<<RWAL))) {
-			UEINTX = 0x6B; 
-		}
-		SREG = intr_state;
-	}
-}
-
-// transmit a character.  0 returned on success, -1 on error
-int8_t usb_serial_putchar(uint8_t c)
-{
-	uint8_t timeout, intr_state;
-
-	// if we're not online (enumerated and configured), error
-	if (!usb_configuration) return -1;
-	// interrupts are disabled so these functions can be
-	// used from the main program or interrupt context,
-	// even both in the same program!
-	intr_state = SREG;
-	cli();
-	UENUM = CDC_TX_ENDPOINT;
-	// if we gave up due to timeout before, don't wait again
-	if (transmit_previous_timeout) {
-		if (!(UEINTX & (1<<RWAL))) {
-			SREG = intr_state;
-			return -1;
-		}
-		transmit_previous_timeout = 0;
-	}
-	// wait for the FIFO to be ready to accept data
-	timeout = UDFNUML + TRANSMIT_TIMEOUT;
-	while (1) {
-		// are we ready to transmit?
-		if (UEINTX & (1<<RWAL)) break;
-		SREG = intr_state;
-		// have we waited too long?  This happens if the user
-		// is not running an application that is listening
-		if (UDFNUML == timeout) {
-			transmit_previous_timeout = 1;
-			return -1;
-		}
-		// has the USB gone offline?
-		if (!usb_configuration) return -1;
-		// get ready to try checking again
-		intr_state = SREG;
-		cli();
-		UENUM = CDC_TX_ENDPOINT;
-	}
-	// actually write the byte into the FIFO
-	UEDATX = c;
-	// if this completed a packet, transmit it now!
-	if (!(UEINTX & (1<<RWAL))) UEINTX = 0x3A;
-	transmit_flush_timer = TRANSMIT_FLUSH_TIMEOUT;
-	SREG = intr_state;
-	return 0;
-}
-
-
-// transmit a character, but do not wait if the buffer is full,
-//   0 returned on success, -1 on buffer full or error 
-int8_t usb_serial_putchar_nowait(uint8_t c)
-{
-	uint8_t intr_state;
-
-	if (!usb_configuration) return -1;
-	intr_state = SREG;
-	cli();
-	UENUM = CDC_TX_ENDPOINT;
-	if (!(UEINTX & (1<<RWAL))) {
-		// buffer is full
-		SREG = intr_state;
-		return -1;
-	}
-	// actually write the byte into the FIFO
-	UEDATX = c;
-		// if this completed a packet, transmit it now!
-	if (!(UEINTX & (1<<RWAL))) UEINTX = 0x3A;
-	transmit_flush_timer = TRANSMIT_FLUSH_TIMEOUT;
-	SREG = intr_state;
-	return 0;
-}
-
-// transmit a buffer.
-//  0 returned on success, -1 on error
-// This function is optimized for speed!  Each call takes approx 6.1 us overhead
-// plus 0.25 us per byte.  12 Mbit/sec USB has 8.67 us per-packet overhead and
-// takes 0.67 us per byte.  If called with 64 byte packet-size blocks, this function
-// can transmit at full USB speed using 43% CPU time.  The maximum theoretical speed
-// is 19 packets per USB frame, or 1216 kbytes/sec.  However, bulk endpoints have the
-// lowest priority, so any other USB devices will likely reduce the speed.  Speed
-// can also be limited by how quickly the PC-based software reads data, as the host
-// controller in the PC will not allocate bandwitdh without a pending read request.
-// (thanks to Victor Suarez for testing and feedback and initial code)
-
-int8_t usb_serial_write(const uint8_t *buffer, uint16_t size)
-{
-	uint8_t timeout, intr_state, write_size;
-
-	// if we're not online (enumerated and configured), error
-	if (!usb_configuration) return -1;
-	// interrupts are disabled so these functions can be
-	// used from the main program or interrupt context,
-	// even both in the same program!
-	intr_state = SREG;
-	cli();
-	UENUM = CDC_TX_ENDPOINT;
-	// if we gave up due to timeout before, don't wait again
-	if (transmit_previous_timeout) {
-		if (!(UEINTX & (1<<RWAL))) {
-			SREG = intr_state;
-			return -1;
-		}
-		transmit_previous_timeout = 0;
-	}
-	// each iteration of this loop transmits a packet
-	while (size) {
-		// wait for the FIFO to be ready to accept data
-		timeout = UDFNUML + TRANSMIT_TIMEOUT;
-		while (1) {
-			// are we ready to transmit?
-			if (UEINTX & (1<<RWAL)) break;
-			SREG = intr_state;
-			// have we waited too long?  This happens if the user
-			// is not running an application that is listening
-			if (UDFNUML == timeout) {
-				transmit_previous_timeout = 1;
-				return -1;
-			}
-			// has the USB gone offline?
-			if (!usb_configuration) return -1;
-			// get ready to try checking again
-			intr_state = SREG;
-			cli();
-			UENUM = CDC_TX_ENDPOINT;
-		}
-
-		// compute how many bytes will fit into the next packet
-		write_size = CDC_TX_SIZE - UEBCLX;
-		if (write_size > size) write_size = size;
-		size -= write_size;
-
-		// write the packet
-		switch (write_size) {
-			#if (CDC_TX_SIZE == 64)
-			case 64: UEDATX = *buffer++;
-			case 63: UEDATX = *buffer++;
-			case 62: UEDATX = *buffer++;
-			case 61: UEDATX = *buffer++;
-			case 60: UEDATX = *buffer++;
-			case 59: UEDATX = *buffer++;
-			case 58: UEDATX = *buffer++;
-			case 57: UEDATX = *buffer++;
-			case 56: UEDATX = *buffer++;
-			case 55: UEDATX = *buffer++;
-			case 54: UEDATX = *buffer++;
-			case 53: UEDATX = *buffer++;
-			case 52: UEDATX = *buffer++;
-			case 51: UEDATX = *buffer++;
-			case 50: UEDATX = *buffer++;
-			case 49: UEDATX = *buffer++;
-			case 48: UEDATX = *buffer++;
-			case 47: UEDATX = *buffer++;
-			case 46: UEDATX = *buffer++;
-			case 45: UEDATX = *buffer++;
-			case 44: UEDATX = *buffer++;
-			case 43: UEDATX = *buffer++;
-			case 42: UEDATX = *buffer++;
-			case 41: UEDATX = *buffer++;
-			case 40: UEDATX = *buffer++;
-			case 39: UEDATX = *buffer++;
-			case 38: UEDATX = *buffer++;
-			case 37: UEDATX = *buffer++;
-			case 36: UEDATX = *buffer++;
-			case 35: UEDATX = *buffer++;
-			case 34: UEDATX = *buffer++;
-			case 33: UEDATX = *buffer++;
-			#endif
-			#if (CDC_TX_SIZE >= 32)
-			case 32: UEDATX = *buffer++;
-			case 31: UEDATX = *buffer++;
-			case 30: UEDATX = *buffer++;
-			case 29: UEDATX = *buffer++;
-			case 28: UEDATX = *buffer++;
-			case 27: UEDATX = *buffer++;
-			case 26: UEDATX = *buffer++;
-			case 25: UEDATX = *buffer++;
-			case 24: UEDATX = *buffer++;
-			case 23: UEDATX = *buffer++;
-			case 22: UEDATX = *buffer++;
-			case 21: UEDATX = *buffer++;
-			case 20: UEDATX = *buffer++;
-			case 19: UEDATX = *buffer++;
-			case 18: UEDATX = *buffer++;
-			case 17: UEDATX = *buffer++;
-			#endif
-			#if (CDC_TX_SIZE >= 16)
-			case 16: UEDATX = *buffer++;
-			case 15: UEDATX = *buffer++;
-			case 14: UEDATX = *buffer++;
-			case 13: UEDATX = *buffer++;
-			case 12: UEDATX = *buffer++;
-			case 11: UEDATX = *buffer++;
-			case 10: UEDATX = *buffer++;
-			case  9: UEDATX = *buffer++;
-			#endif
-			case  8: UEDATX = *buffer++;
-			case  7: UEDATX = *buffer++;
-			case  6: UEDATX = *buffer++;
-			case  5: UEDATX = *buffer++;
-			case  4: UEDATX = *buffer++;
-			case  3: UEDATX = *buffer++;
-			case  2: UEDATX = *buffer++;
-			default:
-			case  1: UEDATX = *buffer++;
-			case  0: break;
-		}
-		// if this completed a packet, transmit it now!
-		if (!(UEINTX & (1<<RWAL))) UEINTX = 0x3A;
-		transmit_flush_timer = TRANSMIT_FLUSH_TIMEOUT;
-		SREG = intr_state;
-	}
-	return 0;
-}
-
-
-// immediately transmit any buffered output.
-// This doesn't actually transmit the data - that is impossible!
-// USB devices only transmit when the host allows, so the best
-// we can do is release the FIFO buffer for when the host wants it
-void usb_serial_flush_output(void)
-{
-	uint8_t intr_state;
-
-	intr_state = SREG;
-	cli();
-	if (transmit_flush_timer) {
-		UENUM = CDC_TX_ENDPOINT;
-		UEINTX = 0x3A;
-		transmit_flush_timer = 0;
-	}
-	SREG = intr_state;
-}
-
-// functions to read the various async serial settings.  These
-// aren't actually used by USB at all (communication is always
-// at full USB speed), but they are set by the host so we can
-// set them properly if we're converting the USB to a real serial
-// communication
-uint32_t usb_serial_get_baud(void)
-{
-	uint32_t res;
-	memcpy(&res, cdc_line_coding, sizeof(res));
-	return res;
-}
-uint8_t usb_serial_get_stopbits(void)
-{
-	return cdc_line_coding[4];
-}
-uint8_t usb_serial_get_paritytype(void)
-{
-	return cdc_line_coding[5];
-}
-uint8_t usb_serial_get_numbits(void)
-{
-	return cdc_line_coding[6];
-}
-uint8_t usb_serial_get_control(void)
-{
-	return cdc_line_rtsdtr;
-}
-// write the control signals, DCD, DSR, RI, etc
-// There is no CTS signal.  If software on the host has transmitted
-// data to you but you haven't been calling the getchar function,
-// it remains buffered (either here or on the host) and can not be
-// lost because you weren't listening at the right time, like it
-// would in real serial communication.
-int8_t usb_serial_set_control(uint8_t signals)
-{
-	uint8_t intr_state;
-
-	intr_state = SREG;
-	cli();
-	if (!usb_configuration) {
-		// we're not enumerated/configured
-		SREG = intr_state;
-		return -1;
-	}
-
-	UENUM = CDC_ACM_ENDPOINT;
-	if (!(UEINTX & (1<<RWAL))) {
-		// unable to write
-		// TODO; should this try to abort the previously
-		// buffered message??
-		SREG = intr_state;
-		return -1;
-	}
-	UEDATX = 0xA1;
-	UEDATX = 0x20;
-	UEDATX = 0;
-	UEDATX = 0;
-	UEDATX = 0; // 0 seems to work nicely.  what if this is 1??
-	UEDATX = 0;
-	UEDATX = 1;
-	UEDATX = 0;
-	UEDATX = signals;
-	UEINTX = 0x3A;
-	SREG = intr_state;
-	return 0;
-}
-
-
-
-/**************************************************************************
- *
- *  Private Functions - not intended for general user consumption....
- *
- **************************************************************************/
-
-
-// USB Device Interrupt - handle all device-level events
-// the transmit buffer flushing is triggered by the start of frame
-//
-ISR(USB_GEN_vect)
-{
-	uint8_t intbits, t;
-
-        intbits = UDINT;
-        UDINT = 0;
-        if (intbits & (1<<EORSTI)) {
-		UENUM = 0;
-		UECONX = 1;
-		UECFG0X = EP_TYPE_CONTROL;
-		UECFG1X = EP_SIZE(ENDPOINT0_SIZE) | EP_SINGLE_BUFFER;
-		UEIENX = (1<<RXSTPE);
-		usb_configuration = 0;
-		cdc_line_rtsdtr = 0;
-        }
-	if (intbits & (1<<SOFI)) {
-		if (usb_configuration) {
-			t = transmit_flush_timer;
-			if (t) {
-				transmit_flush_timer = --t;
-				if (!t) {
-					UENUM = CDC_TX_ENDPOINT;
-					UEINTX = 0x3A;
-				}
-			}
-		}
-	}
-}
-
-
-// Misc functions to wait for ready and send/receive packets
-static inline void usb_wait_in_ready(void)
-{
-	while (!(UEINTX & (1<<TXINI))) ;
-}
-static inline void usb_send_in(void)
-{
-	UEINTX = ~(1<<TXINI);
-}
-static inline void usb_wait_receive_out(void)
-{
-	while (!(UEINTX & (1<<RXOUTI))) ;
-}
-static inline void usb_ack_out(void)
-{
-	UEINTX = ~(1<<RXOUTI);
-}
-
-
-
-// USB Endpoint Interrupt - endpoint 0 is handled here.  The
-// other endpoints are manipulated by the user-callable
-// functions, and the start-of-frame interrupt.
-//
-ISR(USB_COM_vect)
-{
-        uint8_t intbits = UEINT;
-        if (intbits & (1<<CDC_RX_ENDPOINT)) {
-                UENUM = CDC_RX_ENDPOINT;
-                UEIENX = 0;
-                extern void sched_wake_tasks(void);
-                sched_wake_tasks();
-                return;
-        }
-	const uint8_t *list;
-        const uint8_t *cfg;
-	uint8_t i, n, len, en;
-	uint8_t *p;
-	uint8_t bmRequestType;
-	uint8_t bRequest;
-	uint16_t wValue;
-	uint16_t wIndex;
-	uint16_t wLength;
-	uint16_t desc_val;
-	const uint8_t *desc_addr;
-	uint8_t	desc_length;
-
-        UENUM = 0;
-        intbits = UEINTX;
-        if (intbits & (1<<RXSTPI)) {
-                bmRequestType = UEDATX;
-                bRequest = UEDATX;
-                wValue = UEDATX;
-                wValue |= (UEDATX << 8);
-                wIndex = UEDATX;
-                wIndex |= (UEDATX << 8);
-                wLength = UEDATX;
-                wLength |= (UEDATX << 8);
-                UEINTX = ~((1<<RXSTPI) | (1<<RXOUTI) | (1<<TXINI));
-                if (bRequest == GET_DESCRIPTOR) {
-			list = (const uint8_t *)descriptor_list;
-			for (i=0; ; i++) {
-				if (i >= NUM_DESC_LIST) {
-					UECONX = (1<<STALLRQ)|(1<<EPEN);  //stall
-					return;
-				}
-				desc_val = pgm_read_word(list);
-				if (desc_val != wValue) {
-					list += sizeof(struct descriptor_list_struct);
-					continue;
-				}
-				list += 2;
-				desc_val = pgm_read_word(list);
-				if (desc_val != wIndex) {
-					list += sizeof(struct descriptor_list_struct)-2;
-					continue;
-				}
-				list += 2;
-				desc_addr = (const uint8_t *)pgm_read_word(list);
-				list += 2;
-				desc_length = pgm_read_byte(list);
-				break;
-			}
-			len = (wLength < 256) ? wLength : 255;
-			if (len > desc_length) len = desc_length;
-			do {
-				// wait for host ready for IN packet
-				do {
-					i = UEINTX;
-				} while (!(i & ((1<<TXINI)|(1<<RXOUTI))));
-				if (i & (1<<RXOUTI)) return;	// abort
-				// send IN packet
-				n = len < ENDPOINT0_SIZE ? len : ENDPOINT0_SIZE;
-				for (i = n; i; i--) {
-					UEDATX = pgm_read_byte(desc_addr++);
-				}
-				len -= n;
-				usb_send_in();
-			} while (len || n == ENDPOINT0_SIZE);
-			return;
-                }
-		if (bRequest == SET_ADDRESS) {
-			usb_send_in();
-			usb_wait_in_ready();
-			UDADDR = wValue | (1<<ADDEN);
-			return;
-		}
-		if (bRequest == SET_CONFIGURATION && bmRequestType == 0) {
-			usb_configuration = wValue;
-			cdc_line_rtsdtr = 0;
-			transmit_flush_timer = 0;
-			usb_send_in();
-			cfg = endpoint_config_table;
-			for (i=1; i<5; i++) {
-				UENUM = i;
-				en = pgm_read_byte(cfg++);
-				UECONX = en;
-				if (en) {
-					UECFG0X = pgm_read_byte(cfg++);
-					UECFG1X = pgm_read_byte(cfg++);
-				}
-			}
-        		UERST = 0x1E;
-        		UERST = 0;
-			return;
-		}
-		if (bRequest == GET_CONFIGURATION && bmRequestType == 0x80) {
-			usb_wait_in_ready();
-			UEDATX = usb_configuration;
-			usb_send_in();
-			return;
-		}
-		if (bRequest == CDC_GET_LINE_CODING && bmRequestType == 0xA1) {
-			usb_wait_in_ready();
-			p = cdc_line_coding;
-			for (i=0; i<7; i++) {
-				UEDATX = *p++;
-			}
-			usb_send_in();
-			return;
-		}
-		if (bRequest == CDC_SET_LINE_CODING && bmRequestType == 0x21) {
-			usb_wait_receive_out();
-			p = cdc_line_coding;
-			for (i=0; i<7; i++) {
-				*p++ = UEDATX;
-			}
-			usb_ack_out();
-			usb_send_in();
-			return;
-		}
-		if (bRequest == CDC_SET_CONTROL_LINE_STATE && bmRequestType == 0x21) {
-			cdc_line_rtsdtr = wValue;
-			usb_wait_in_ready();
-			usb_send_in();
-			return;
-		}
-		if (bRequest == GET_STATUS) {
-			usb_wait_in_ready();
-			i = 0;
-			#ifdef SUPPORT_ENDPOINT_HALT
-			if (bmRequestType == 0x82) {
-				UENUM = wIndex;
-				if (UECONX & (1<<STALLRQ)) i = 1;
-				UENUM = 0;
-			}
-			#endif
-			UEDATX = i;
-			UEDATX = 0;
-			usb_send_in();
-			return;
-		}
-		#ifdef SUPPORT_ENDPOINT_HALT
-		if ((bRequest == CLEAR_FEATURE || bRequest == SET_FEATURE)
-		  && bmRequestType == 0x02 && wValue == 0) {
-			i = wIndex & 0x7F;
-			if (i >= 1 && i <= MAX_ENDPOINT) {
-				usb_send_in();
-				UENUM = i;
-				if (bRequest == SET_FEATURE) {
-					UECONX = (1<<STALLRQ)|(1<<EPEN);
-				} else {
-					UECONX = (1<<STALLRQC)|(1<<RSTDT)|(1<<EPEN);
-					UERST = (1 << i);
-					UERST = 0;
-				}
-				return;
-			}
-		}
-		#endif
-        }
-	UECONX = (1<<STALLRQ) | (1<<EPEN);	// stall
-}
-
-
diff --git a/lib/pjrc_usb_serial/usb_serial.h b/lib/pjrc_usb_serial/usb_serial.h
deleted file mode 100644
index 14c5b1a7..00000000
--- a/lib/pjrc_usb_serial/usb_serial.h
+++ /dev/null
@@ -1,124 +0,0 @@
-#ifndef usb_serial_h__
-#define usb_serial_h__
-
-#include <stdint.h>
-
-// setup
-void usb_init(void);			// initialize everything
-uint8_t usb_configured(void);		// is the USB port configured
-
-// receiving data
-int16_t usb_serial_getchar(void);	// receive a character (-1 if timeout/error)
-uint8_t usb_serial_available(void);	// number of bytes in receive buffer
-void usb_serial_flush_input(void);	// discard any buffered input
-
-// transmitting data
-int8_t usb_serial_putchar(uint8_t c);	// transmit a character
-int8_t usb_serial_putchar_nowait(uint8_t c);  // transmit a character, do not wait
-int8_t usb_serial_write(const uint8_t *buffer, uint16_t size); // transmit a buffer
-void usb_serial_flush_output(void);	// immediately transmit any buffered output
-
-// serial parameters
-uint32_t usb_serial_get_baud(void);	// get the baud rate
-uint8_t usb_serial_get_stopbits(void);	// get the number of stop bits
-uint8_t usb_serial_get_paritytype(void);// get the parity type
-uint8_t usb_serial_get_numbits(void);	// get the number of data bits
-uint8_t usb_serial_get_control(void);	// get the RTS and DTR signal state
-int8_t usb_serial_set_control(uint8_t signals); // set DSR, DCD, RI, etc
-
-// constants corresponding to the various serial parameters
-#define USB_SERIAL_DTR			0x01
-#define USB_SERIAL_RTS			0x02
-#define USB_SERIAL_1_STOP		0
-#define USB_SERIAL_1_5_STOP		1
-#define USB_SERIAL_2_STOP		2
-#define USB_SERIAL_PARITY_NONE		0
-#define USB_SERIAL_PARITY_ODD		1
-#define USB_SERIAL_PARITY_EVEN		2
-#define USB_SERIAL_PARITY_MARK		3
-#define USB_SERIAL_PARITY_SPACE		4
-#define USB_SERIAL_DCD			0x01
-#define USB_SERIAL_DSR			0x02
-#define USB_SERIAL_BREAK		0x04
-#define USB_SERIAL_RI			0x08
-#define USB_SERIAL_FRAME_ERR		0x10
-#define USB_SERIAL_PARITY_ERR		0x20
-#define USB_SERIAL_OVERRUN_ERR		0x40
-
-// This file does not include the HID debug functions, so these empty
-// macros replace them with nothing, so users can compile code that
-// has calls to these functions.
-#define usb_debug_putchar(c)
-#define usb_debug_flush_output()
-
-
-
-// Everything below this point is only intended for usb_serial.c
-#ifdef USB_SERIAL_PRIVATE_INCLUDE
-#include <avr/io.h>
-#include <avr/pgmspace.h>
-#include <avr/interrupt.h>
-
-#define EP_TYPE_CONTROL			0x00
-#define EP_TYPE_BULK_IN			0x81
-#define EP_TYPE_BULK_OUT		0x80
-#define EP_TYPE_INTERRUPT_IN		0xC1
-#define EP_TYPE_INTERRUPT_OUT		0xC0
-#define EP_TYPE_ISOCHRONOUS_IN		0x41
-#define EP_TYPE_ISOCHRONOUS_OUT		0x40
-#define EP_SINGLE_BUFFER		0x02
-#define EP_DOUBLE_BUFFER		0x06
-#define EP_SIZE(s)	((s) == 64 ? 0x30 :	\
-			((s) == 32 ? 0x20 :	\
-			((s) == 16 ? 0x10 :	\
-			             0x00)))
-
-#define MAX_ENDPOINT		4
-
-#define LSB(n) (n & 255)
-#define MSB(n) ((n >> 8) & 255)
-
-#if defined(__AVR_AT90USB162__)
-#define HW_CONFIG() 
-#define PLL_CONFIG() (PLLCSR = ((1<<PLLE)|(1<<PLLP0)))
-#define USB_CONFIG() (USBCON = (1<<USBE))
-#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
-#elif defined(__AVR_ATmega32U4__)
-#define HW_CONFIG() (UHWCON = 0x01)
-#define PLL_CONFIG() (PLLCSR = 0x12)
-#define USB_CONFIG() (USBCON = ((1<<USBE)|(1<<OTGPADE)))
-#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
-#elif defined(__AVR_AT90USB646__)
-#define HW_CONFIG() (UHWCON = 0x81)
-#define PLL_CONFIG() (PLLCSR = 0x1A)
-#define USB_CONFIG() (USBCON = ((1<<USBE)|(1<<OTGPADE)))
-#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
-#elif defined(__AVR_AT90USB1286__)
-#define HW_CONFIG() (UHWCON = 0x81)
-#define PLL_CONFIG() (PLLCSR = 0x16)
-#define USB_CONFIG() (USBCON = ((1<<USBE)|(1<<OTGPADE)))
-#define USB_FREEZE() (USBCON = ((1<<USBE)|(1<<FRZCLK)))
-#endif
-
-// standard control endpoint request types
-#define GET_STATUS			0
-#define CLEAR_FEATURE			1
-#define SET_FEATURE			3
-#define SET_ADDRESS			5
-#define GET_DESCRIPTOR			6
-#define GET_CONFIGURATION		8
-#define SET_CONFIGURATION		9
-#define GET_INTERFACE			10
-#define SET_INTERFACE			11
-// HID (human interface device)
-#define HID_GET_REPORT			1
-#define HID_GET_PROTOCOL		3
-#define HID_SET_REPORT			9
-#define HID_SET_IDLE			10
-#define HID_SET_PROTOCOL		11
-// CDC (communication class device)
-#define CDC_SET_LINE_CODING		0x20
-#define CDC_GET_LINE_CODING		0x21
-#define CDC_SET_CONTROL_LINE_STATE	0x22
-#endif
-#endif
diff --git a/lib/pjrc_usb_serial/usb_serial.patch b/lib/pjrc_usb_serial/usb_serial.patch
deleted file mode 100644
index 73fef81a..00000000
--- a/lib/pjrc_usb_serial/usb_serial.patch
+++ /dev/null
@@ -1,108 +0,0 @@
---- ../../../lib/pjrc/usb_serial/usb_serial.c	2011-04-19 05:54:12.000000000 -0400
-+++ usb_serial.c	2017-08-07 11:32:47.106357362 -0400
-@@ -30,6 +30,7 @@
- // Version 1.6: fix zero length packet bug
- // Version 1.7: fix usb_serial_set_control
- 
-+#include <string.h>
- #define USB_SERIAL_PRIVATE_INCLUDE
- #include "usb_serial.h"
- 
-@@ -146,7 +147,7 @@
- // in here should only be done by those who've read chapter 9 of the USB
- // spec and relevant portions of any USB class specifications!
- 
--static uint8_t PROGMEM device_descriptor[] = {
-+static const uint8_t PROGMEM device_descriptor[] = {
- 	18,					// bLength
- 	1,					// bDescriptorType
- 	0x00, 0x02,				// bcdUSB
-@@ -164,7 +165,7 @@
- };
- 
- #define CONFIG1_DESC_SIZE (9+9+5+5+4+5+7+9+7+7)
--static uint8_t PROGMEM config1_descriptor[CONFIG1_DESC_SIZE] = {
-+static const uint8_t PROGMEM config1_descriptor[CONFIG1_DESC_SIZE] = {
- 	// configuration descriptor, USB spec 9.6.3, page 264-266, Table 9-10
- 	9, 					// bLength;
- 	2,					// bDescriptorType;
-@@ -248,22 +249,22 @@
- 	uint8_t bDescriptorType;
- 	int16_t wString[];
- };
--static struct usb_string_descriptor_struct PROGMEM string0 = {
-+static const struct usb_string_descriptor_struct PROGMEM string0 = {
- 	4,
- 	3,
- 	{0x0409}
- };
--static struct usb_string_descriptor_struct PROGMEM string1 = {
-+static const struct usb_string_descriptor_struct PROGMEM string1 = {
- 	sizeof(STR_MANUFACTURER),
- 	3,
- 	STR_MANUFACTURER
- };
--static struct usb_string_descriptor_struct PROGMEM string2 = {
-+static const struct usb_string_descriptor_struct PROGMEM string2 = {
- 	sizeof(STR_PRODUCT),
- 	3,
- 	STR_PRODUCT
- };
--static struct usb_string_descriptor_struct PROGMEM string3 = {
-+static const struct usb_string_descriptor_struct PROGMEM string3 = {
- 	sizeof(STR_SERIAL_NUMBER),
- 	3,
- 	STR_SERIAL_NUMBER
-@@ -271,7 +272,7 @@
- 
- // This table defines which descriptor data is sent for each specific
- // request from the host (in wValue and wIndex).
--static struct descriptor_list_struct {
-+static const struct descriptor_list_struct {
- 	uint16_t	wValue;
- 	uint16_t	wIndex;
- 	const uint8_t	*addr;
-@@ -324,7 +325,7 @@
-         UDCON = 0;				// enable attach resistor
- 	usb_configuration = 0;
- 	cdc_line_rtsdtr = 0;
--        UDIEN = (1<<EORSTE)|(1<<SOFE);
-+        UDIEN = (1<<EORSTE);
- 	sei();
- }
- 
-@@ -358,6 +359,7 @@
- 			UEINTX = 0x6B;
- 			goto retry;
- 		}	
-+		UEIENX = (1<<RXOUTE);
- 		SREG = intr_state;
- 		return -1;
- 	}
-@@ -646,7 +648,9 @@
- // communication
- uint32_t usb_serial_get_baud(void)
- {
--	return *(uint32_t *)cdc_line_coding;
-+	uint32_t res;
-+	memcpy(&res, cdc_line_coding, sizeof(res));
-+	return res;
- }
- uint8_t usb_serial_get_stopbits(void)
- {
-@@ -772,7 +776,14 @@
- //
- ISR(USB_COM_vect)
- {
--        uint8_t intbits;
-+        uint8_t intbits = UEINT;
-+        if (intbits & (1<<CDC_RX_ENDPOINT)) {
-+                UENUM = CDC_RX_ENDPOINT;
-+                UEIENX = 0;
-+                extern void sched_wake_tasks(void);
-+                sched_wake_tasks();
-+                return;
-+        }
- 	const uint8_t *list;
-         const uint8_t *cfg;
- 	uint8_t i, n, len, en;