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Update the firmware of Arduino boards based on Atmel AVR

Project description


PyArduinoFlash is an open source library in Python for updating the firmware of Arduino boards that use the ATmegaBOOT_168.c bootloader, for example Arduino Nano.

The intention is to have a class that can be imported into any python project to update the Arduinos through the serial port.

It implements a subset of Atmel's STK-500 protocol, using as reference the source code of all Arduino bootloaders that use Atmel as a processor. ArduinoCore-avr

As an example of use, there is an APP in KivyMd and Kivy that exposes through a GUI all the methods required to update and verify the firmware.


Installation, Documentation and Examples

For now it consists of copying the file to the Python project

Documentation and Examples

    from intelhex import IntelHex
    from arduinobootloader.arduinobootloader import ArduinoBootloader

    ih = IntelHex()
    ab = ArduinoBootloader()

        if not ab.board_request():

        print("botloader version: {} hardware version: {}".format(ab.sw_version, ab.hw_version))

        if not ab.cpu_signature():

        print("cpu name: {}".format(ab.cpu_name) )

        ih.fromfile("firmware_file.hex", format='hex')

        for address in range(0, ih.maxaddr(), ab.cpu_page_size):
            buffer = ih.tobinarray(start=address, size=ab.cpu_page_size)
            if not ab.write_memory(buffer, address):
               print("Write error") 

        for address in range(0, ih.maxaddr(), ab.cpu_page_size):
            buffer = ih.tobinarray(start=address, size=ab.cpu_page_size)
            read_buffer = ab.read_memory(address, ab.cpu_page_size)
            if not len(read_buffer):
               print("Read error") 

            if buffer != read_buffer:
               print("File not match")


The parsing of the file in Intel hexadecimal format is done with the IntelHex library.

To have an instance of the class use ab = ArduinoBootloader() The next step is to establish the connection with the bootloader of the Arduino board with that returns True when it is successful.

As the library needs the information of the CPU to know the size of the page, it is necessary to use the functions ab.board_request() and ab.cpu_signature()

If the previous functions were executed successfully (they return True), now you have to open the hexadecimal file with the ih.fromfile("firmware_file.hex", format='hex') function. If there are errors in the format or the file path is invalid, exceptions are thrown.

As the CPU is flashed by pages, with the function ih.tobinarray(start=address, size=ab.cpu_page_size) the current page is obtained (according to the address).

For the bootloader to write it, use the function ab.write_memory(buffer, address) which take the buffer and the current address as parameters. Returns True when completed successfully.

The reading to verify the recording is done in the same way, with the exception that the function returns the buffer read. If it is None it indicates that there were problems.

The bootloader begins the execution of the firmware after a period of time without receiving communication; nevertheless it is convenient to execute the function ab.leave_prg_mode().

Finally, to release the serial port, you have to execute the function ab.close().


The Script folder contains file that allows update or read the firmware of Arduino boards.

One of the purposes is to show the use of the PyArduinoBootloader library in conjunction with the IntelHex library to process hexadecimal files.

Use the argparse library, to read the command line (file and options).

And to indicate the progress the progressbar2 library.

usage: [-h] [--version] [-r | -u] filename

arduino flash utility

positional arguments:
  filename      filename in hexadecimal Intel format

optional arguments:
  -h, --help    show this help message and exit
  --version     script version
  -b BAUDRATE, --baudrate BAUDRATE
                        old bootolader (57600) Optiboot (115200)
  -r, --read            read the cpu flash memory
  -u, --update          update cpu flash memory

The following capture shows the reading of the flash memory of an Arduino Nano board.

And the next shows the firmware update of an Arduino Nano board.


If you need assistance, contact me:



  • PyArduinoFlash is released under the terms of the MIT License. Please refer to the LICENSE file.

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