NRFutil (.exe, Windows) needs a larger write timeout

[waltje]

I run the Arduino IDE under a VM with VMware - which runs just fine.

The thing here is, that once I want to program (flash) the resulting binary into a SuperMicro board, I get the following:

Upgrading target on COM20 with DFU package Y:\TEMP\arduino_build_677040\serial_echo.ino.zip. Flow control is disabled, Single bank, Touch disabled
Opened serial port COM20
Starting DFU upgrade of type 4, SoftDevice size: 0, bootloader size: 0, application size: 49232
Sending DFU start packet
Sending DFU init packet
Sending firmware file

Failed to upgrade target. Error is: Write timeout
Traceback (most recent call last):
  File "__main__.py", line 296, in serial
  File "dfu\dfu.py", line 235, in dfu_send_images
  File "dfu\dfu.py", line 206, in _dfu_send_image
  File "dfu\dfu_transport_serial.py", line 213, in send_firmware
  File "dfu\dfu_transport_serial.py", line 241, in send_packet
  File "serial\serialwin32.py", line 325, in write
serial.serialutil.SerialTimeoutException: Write timeout

Possible causes:
- Selected Bootloader version does not match the one on Bluefruit device.
    Please upgrade the Bootloader or select correct version in Tools->Bootloader.
- Baud rate must be 115200, Flow control must be off.
- Target is not in DFU mode. Ground DFU pin and RESET and release both to enter DFU mode.

which most likely is caused by the disconnect-reconnect of the USB port through VMware, which takes longer than it would on a direct connect system. Adafruit suggests:

"... the default timeout for acknowledgement packets is too short. A GitHub issue suggests increasing the ACK_PACKET_TIMEOUT constant in the nordicsemi/dfu/dfu_transport_serial.py file within the adafruit-nrfutil library to a higher value like 2.0 seconds."

A value of 2-3 seconds should indeed overcome this.