QUERY · ISSUE

RP2 SPI: Instantiating with spi=None does not behave sensibly.

openby peterhinchopened 2023-03-20updated 2024-09-02

bugport-rp2

The constructor accepts None as an arg to miso, but still instantiates the default pin.

The clear intent is to create an output-only interface. Either it should reject the arg or (preferably) it should not instantiate a pin. Current behaviour can lead to unexpected pin conflicts.

This should also apply to mosi.

CANDIDATE · PULL REQUEST

esp32/machine_hw_spi: Allow None for unused pins in initializer.

closedby jonathanhoggopened 2021-06-16updated 2021-06-17

port-esp32

Make the hardware SPI initializer method match the init() method by
allowing None to be given for sck/mosi/miso to specify an unused
signal.

Assessment

Q Qwen · high

Both items address the same conceptual issue: how the SPI constructor handles None values for pins (MISO/MOSI). However, they target different ports (RP2 vs ESP32) and have different specific behaviors. The query (issue #11082) reports a bug where RP2 SPI incorrectly instantiates default pins when None is passed, causing pin conflicts. The candidate (PR #7405) implements a fix for ESP32 SPI to allow None for unused pins. While they share the same underlying concept and API design goal, the RP2 bug likely has a different root cause and requires a separate fix. The ESP32 PR does not resolve the RP2 issue.

Suggested action

Keep both items open. The RP2 issue (#11082) requires its own fix in ports/rp2/machine_spi.c. The ESP32 PR (#7405) is a separate implementation for a different port.

RP2 SPI: Instantiating with spi=None does not behave sensibly.

esp32/machine_hw_spi: Allow None for unused pins in initializer.

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