zephyr: do dynamic bus allocation on CLUE boards #11603

Activity

1. dhalbert

   added this to the 11.0.0 milestone on Oct 14, 2026
2. dhalbert

   added a parent issue on Oct 14, 2026

   • Zephyr: allocate I2C, SPI, UART buses dynamically instead of using the fixed assignments in devicetree #11596
3. dhalbert

   added

   busio

   zephyr

   on Oct 14, 2026
4. mikeysklar commented on Oct 28, 2026

   

   mikeysklar

   on Oct 28, 2026

   Collaborator

   More actions

   Tested on a CLUE with 11.0.0-alpha.2, which includes #11576. board.I2C() finds all five onboard sensors. I2C, SPI and UART on other pins can all be open at once alongside the display, and freed buses can be reused. Closing.

   Adafruit CircuitPython 11.0.0-alpha.2 on 2026-10-21; CLUE nRF52840 Express with nrf52840
   Board ID:adafruit_clue_nrf52840_zephyr
   UID:3909ACB25C7C1FC6
   

   Test code and output

   import board
   import busio
   
   i2c = board.I2C()
   while not i2c.try_lock():
       pass
   print("onboard I2C:", [hex(a) for a in i2c.scan()])
   i2c.unlock()
   print("display:", board.DISPLAY.width, "x", board.DISPLAY.height)
   
   i2c1 = busio.I2C(board.P8, board.P12)
   spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
   uart = busio.UART(board.TX, board.RX)
   print("I2C P8/P12, SPI, UART TX/RX open together: OK")
   
   try:
       busio.I2C(board.P5, board.P11)
   except ValueError as e:
       print("third I2C:", e)
   
   i2c1.deinit()
   i2c2 = busio.I2C(board.P5, board.P11)
   print("I2C P5/P11 after freeing P8/P12: OK")
   
   uart.deinit()
   board.UART().deinit()
   uart = busio.UART(board.TX, board.RX)
   print("busio.UART after board.UART().deinit(): OK")
   
   for bus in (i2c2, spi, uart):
       bus.deinit()

   onboard I2C: ['0x1c', '0x39', '0x44', '0x6a', '0x77']
   display: 240 x 240
   I2C P8/P12, SPI, UART TX/RX open together: OK
   third I2C: All I2C peripherals are in use
   I2C P5/P11 after freeing P8/P12: OK
   busio.UART after board.UART().deinit(): OK
   
5. mikeysklar

   closed this as completedon Oct 28, 2026