Upload fails on avr:leonardo about arduino-cmake-toolchain HOT 2 OPEN

This board needs to be switched to bootloader mode by hitting the reset button twice before attempting to upload.
In my case, there is no reset button(DFRobot Beetle). It can be done by opening the serial port at 1200 bauds and then closing it.
The board is then ready for upload.

Edit: I'm leaving this ticket open and let you decide if this project needs to be updated to address the issue.

from arduino-cmake-toolchain.

I needed to reset the Leonardo in an automated way, because I'm flashing and testing various Arduinos from a CI pipeline in the cloud.

As @zeechs says, you need to open the serial port (probably /dev/ttyACM0) with a baud of 1200, and then close it. The LEDs will flash the same pattern as the reset button while the firmware is flashable. After resetting via the button or open/closing the serial port, the Leonardo is flashable for about 8 seconds.

Here's my GitHub Actions yaml for my flashing and testing:

jobs:
  build:
    steps:
      - name: Upload Ardino hex to /dev/ttyACM0
        run: |
          ./scripts/reset_leonardo.py /dev/ttyACM0
          sleep 2
          cmake --build ./build --target upload -- TARGET=leonardo_node SERIAL_PORT=/dev/ttyACM0
          sleep 2

      - name: Test Ardino
        run: |
          ./firmware_test.py

And here's the contents of reset_leonardo.py:

#!/usr/bin/env python3
################################################################################
#
#  Copyright (C) 2021 Garrett Brown
#  SPDX-License-Identifier: Apache-2.0
#
################################################################################

import serial
import sys

# Environment parameters
SERIAL_PORT = sys.argv[1]

# Open the Leonardo tty at 1200 baud and then close to reset into programming
# mode
print(f"Opening {SERIAL_PORT} at 1200 baud")
ser = serial.Serial(SERIAL_PORT, 1200)

print(f"Closing {SERIAL_PORT}")
ser.close()

print("Arduino Leonardo is now in reset mode for 8 seconds")

from arduino-cmake-toolchain.