Segmentation fault with pynrfjprog

[Andy]

Hello,

I'm writing a python script to flash batches of boards with NRF52's.

This is the part of the script that flashes the boards:

def flash_program(hex_file_path, serial_number):

    # Detect the device family of your device. Initialize an API object with UNKNOWN family and read the device's family
    # This step is performed so this example can be run in all devices without customer input
    print "# Opening API with device family NRF52."

    # Initialize an API object with the target family. This will load nrfjprog.dll with the proper target family.
    api = API.API('NRF52')

    try:
        # Open the loaded DLL and connect to an emulator probe. If several are connected a pop up will appear.
        api.open()
        api.connect_to_emu_without_snr(1000)

        # Erase all the flash of the device.
        print "# Erasing all flash in the microcontroller."
        api.erase_all()

        # Parse the hex file with the help of the HEX module
        print "# Parsing hex file into segments."
        test_program = Hex.Hex(hex_file_path)

        # Program the parsed hex into the device's memory.
        print('# Writing %s to device.' % hex_file_path)
        for segment in test_program:
            api.write(segment.address, segment.data, True)

        # Free resources
        test_program = None

        print "# Writing serial number to memory address 0x10001080, use NVMC"
        api.write_u32(0x10001080, ctypes.c_uint32(serial_number).value, True)

        # Read back the serial number
        print "# Programmed serial number: " + hex(api.read_u32(0x10001080))

        # Reset the device and run.
        api.sys_reset()
        api.go()
        print "# Application running."

        # Close the loaded DLL to free resources.
        api.close()
        print "# Programming finished."
        return 0
    except Exception:
        # Close the loaded DLL to free resources.
        api.close()
        return -1

I call that function inside a for-loop until all the boards are flashed. The code works, the boards are flashed, but after a while I get a segmentation fault -11. Is it maybe a memory leak?

Any clues will be appreciated.

[Simen August Tinderholt]

Hm, I can't see anything wrong with the script, but the garbage collection in python can be unreliable. Can you try:

with API('NRF52') as api:
    api.connect_to_emu_without_snr(1000)

    # Erase all the flash of the device.
    print "# Erasing all flash in the microcontroller."
    api.erase_all()

    # Parse the hex file with the help of the HEX module
    print "# Parsing hex file into segments."
    test_program = Hex.Hex(hex_file_path)

    # Program the parsed hex into the device's memory.
    print('# Writing %s to device.' % hex_file_path)
    for segment in test_program:
        api.write(segment.address, segment.data, True)

    # Free resources
    test_program = None

    print "# Writing serial number to memory address 0x10001080, use NVMC"
    api.write_u32(0x10001080, ctypes.c_uint32(serial_number).value, True)

    # Read back the serial number
    print "# Programmed serial number: " + hex(api.read_u32(0x10001080))

    # Reset the device and run.
    api.sys_reset()
    api.go()
    print "# Application running."

print "# Programming finished."
return 0

That should ensure that the close() is called whatever happens (it's always called when exiting the with statement), and (maybe) help the python garbage collector out.

[Simen August Tinderholt]

If that doesn't work you might be dealing with a memory leak in the Segger DLL.

You can fix that by instantiating a single API, and passing it around, instead of creatnig a new one for every device.

[Andy]

With that code I get this error:

 

# Opening API with device family NRF52.
Traceback (most recent call last):
  File "main.py", line 309, in <module>
    main()
  File "main.py", line 304, in main
    flash_batch(programmer, uart)
  File "main.py", line 203, in flash_batch
    result = flash_program(programmer)
  File "main.py", line 82, in flash_program
    with API('NRF52') as api:
TypeError: 'module' object is not callable

[Simen August Tinderholt]

Sorry, that should be API.API('NRF52').

[Andy]

It seems to have solved the problem. I'll keep testing for a while more and I'll mark your reply as an answer once I'm sure :) Otherwise, I'll update again here. Thanks!