Sparkfun Pro nRF52840 Mini - Need to upload twice

Development Boards Other Microcontrollers
1

Hello, I am seeing consistent behaviour on my Sparkfun Pro nRF52840 Mini where code needs to be uploaded twice for changes to take effect. The following sequence happened in both the Arduino IDE 1.8.18 and nRF5 SDK via VS Code, for several different example scripts.

(1.8.18 was used due to a known issue with adafruit-nrfutil on Macs with Arduino IDE 2.0.0 or later. With newer IDE versions, code does not compile).

  1. Press pin 13 and reset button to enter bootloader mode. Built-in LED flashes rapidly as expected.
  2. Code is uploaded. Operation is reported as a success in terminal.
  3. No matter what the code is supposed to do, the built-in LED flashes at a frequency of 2 Hz.
  4. Repeat step 1, again behaves as expected.
  5. Code is uploaded ‘successfully’ again.
  6. Code functions as expected.

Is this usual behaviour? Sometimes, when step 1) is done, the built-in LED turns completely off. In these cases, 1) needs to be repeated 3-5 times before the LED begins blinking rapidly again.

2

It sounds like the port/cable might be a bit buggy? Try some alternates and see if that changes anything…that’d be my first guess, second guess is macOS is doing something that interrupts it? Be sure to enable unkown dev mode

Also: Are you running the verification before upload? Do ALL sketches do the same?