How can I force an Arduino Leonardo to reset with AVRDUDE?

Question

I want to compile and transfer an Arduino program by myself on a Leonardo board.

Everything works great with the Arduino official IDE. I have enabled verbose mode for compiling and bytecode transfer.

I can see each command line.
I want to understand each line.

Everything is good except last step: transfer with AVRDUDE. If I type exactly the same command, I get an error:

.avrdude: butterfly_recv(): programmer is not responding

This error is not present if I upload code with the Arduino IDE.

I can see a difference - the Arduino IDE displays this line before the AVRDUDE call:

Forcing reset using 1200 bps open/close on port /dev/cu.usbmodem1431

How can I make this reset by command line?

Answer 1

I had the same issue on macOS, and I came up with the following Bash script:

# Find the Arduino port
ARDUINO_UPLOAD_PORT="$(find /dev/cu.usbmodem* | head -n 1)"

# Reset the Arduino
stty -f "${ARDUINO_UPLOAD_PORT}" 1200

# Wait for it...
while :; do
  sleep 0.5
  [ -c "${ARDUINO_UPLOAD_PORT}" ] && break
done

# ...upload!
avrdude "${OPTIONS[@]}"

The while loop is the trick! It's going to proceed as soon as the Arduino port is back online.

This is part of a Makefile I wrote for the project Sesame.

Answer 2

On Windows, in a command prompt, the same solution, slightly different batch file:

It determines the bootloader COM port as well. Note that just only the Leonardo to be flashed should be connected!

@echo off
echo Upgrade procedure starting.
if %1.==. goto error
set hexfile=%1
set comportA=NONE
set comportB=NONE
if not exist %hexfile% goto error
for /f "usebackq" %%B in (`wmic path Win32_SerialPort Where "Caption LIKE '%%Leonardo%%'" Get DeviceID ^| FIND "COM"`) do set comportA=%%B
if %comportA%==NONE goto nodevice
echo COM port for Arduino device is detected as %comportA%.
echo Reset Arduino into bootloader
mode %comportA%: baud=12 > nul
timeout 2 > nul
for /f "usebackq" %%B in (`wmic path Win32_SerialPort Where "Caption LIKE '%%Leonardo%%'" Get DeviceID ^| FIND "COM"`) do set comportB=%%B
if %comportB%==NONE goto nobldevice
echo COM port for Arduino bootloader device is detected as %comportB%.
echo.
echo Starting AVR Downloader/UploaDEr.....
avrdude -pm32u4 -cavr109 -D -P%comportB% -b57600 -Uflash:w:%hexfile%
goto upgradedone
:nodevice
echo No matching module found, you should connect the module you want to upgrade.
goto end
:nobldevice
echo Reset into bootloader failed, please try again...
goto end
:error
Echo Missing parameter or file, you should provide the full filename of an existing .hex file you want to use.
goto end
:upgradedone
echo.
echo Upgrade done!
:end

Answer 3

I had the same problem. I've tried opening and closing the ACM0 port with a Python script at 1200 baud, as someone already mentioned. It didn't work for me. Then I have received half-advice to try toggling RTS/DTS and that will make autoreset. So in the end I found the solution (at least for me) on Linux Mint 18.2 (Sonya):

#! /usr/bin/python

import sys
import serial

com = serial.Serial(sys.argv[1], 1200)
com.dtr=False
com.close()


python ./reset.py "/dev/ttyACM0"

dmesg shows me:

[21850.047120] cdc_acm 1-1:1.0: ttyACM0: USB ACM device
[22093.700327] usb 1-1: USB disconnect, device number 53
[22094.034133] usb 1-1: new full-speed USB device number 54 using xhci_hcd
[22094.175377] usb 1-1: New USB device found, idVendor=2341, idProduct=0036
[22094.175381] usb 1-1: New USB device strings: Mfr=2, Product=1, SerialNumber=0
[22094.175384] usb 1-1: Product: Arduino Leonardo
[22094.175387] usb 1-1: Manufacturer: Arduino LLC
[22094.175964] cdc_acm 1-1:1.0: ttyACM0: USB ACM device