Automatic software reset for the Arduino Leonardo/Micro

arduino_reset.py

#!/usr/bin/env python
from __future__ import print_function
import serial, sys
from time import sleep

#
# Arduino Leonardo/Micro automatic software reset tool.
#
# Calvin Li, 2015-04-03
#


# command-line argument is the port the Arduino is on
serialPort = sys.argv[1]
print("Resetting the Arduino Leonardo/Micro at {}... ".format(serialPort), end="")


# First we open and close the port at some normal baudrate.
ser = serial.Serial(port=serialPort, baudrate=9600)
ser.close()


# Now, we open the port at the magic 1200 baud.
ser.baudrate = 1200
ser.open()

# Tricky, completely undocumented bit: RTS must be HIGH and DTR LOW.
# Otherwise absolutely nothing happens!
# ...yeah, I know.
ser.setRTS(True)
ser.setDTR(False)

# Close the 1200 baud connection, triggering a reset of the Arduino.
# The bootloader will run for 8 seconds (14 blinks).
ser.close()

# yay!!!
print("done.")


# Addendum: If this is used right before uploading new code,
# we need to give the bootloader some time to start up.
time.sleep(2)