QUERY · ISSUE

SoftSPI: Implement 'bits' and 'firstbit' parameters

openby sebert007opened 2023-03-10updated 2023-03-11

enhancement

SPI offers both this parameters to specify. SoftSPI rejects both of them, although they are really useful (and needed).

But first probably this issue should be fixed along with it.

#5225

CANDIDATE · PULL REQUEST

extmod/machine_spi.c: Support firstbit=machine.LSB for machine.SoftSPI.

mergedby robert-hhopened 2024-07-09updated 2024-07-14

extmod

Easy to add, sometimes needed and sought for.

For the change the definition of MICROPY_PY_MACHINE_SPI_MSB/ -LSB was moved to py/mpconfig.h, making them available to all ports. The identical defines in esp32/mpconfigport.h were deleted.

Tested with the RP2 and ESP32 port.

Assessment

S Sonnet · medium

PR #15436 directly targets SoftSPI's missing firstbit parameter, which is one of the two parameters requested in issue #10999. The PR implements firstbit=machine.LSB support by adding bit-swapping logic in drivers/bus/softspi.c and wiring it through extmod/machine_spi.c. However, the query issue also requests the bits parameter (variable word size), which is not addressed by this PR. The fix is therefore partial — one of the two feature requests is implemented, the other is not. Classification is LIKELY_DUPLICATE rather than DUPLICATE because the issue is only half-resolved.

Suggested action

Check whether PR #15436 has been merged. If merged, partially close the issue with a comment noting that `firstbit` is now supported but `bits` (variable word size) remains unimplemented — keep the issue open or open a new focused issue for the `bits` parameter. If the PR is still open, link it to issue #10999 and note the `bits` parameter is still out of scope.

SoftSPI: Implement 'bits' and 'firstbit' parameters

extmod/machine_spi.c: Support firstbit=machine.LSB for machine.SoftSPI.

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