Pin missing from PeripheralPins.c

[brandonboesch]

Description

• Type: Bug
• Priority: Major

---

Target
STM32F401 Nucleo

mbed-os sha:
f4864dc Merge pull request #3930 from ARMmbed/release-candidate

Issue
The issue is in regards to PeripheralPins.c for the STM32F401 Nucleo board which can be found at :
targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F401xE/TARGET_NUCLEO_F401RE/PeripheralPins.c

In this file, the pinmap for SPI_SSEL is missing its default arduino header pin that is defined in PinNames.h The image below shows two different pin maps for the device from PeripheralPins.c, SPI_SCLK and SPI_SSEL. Notice how SPI_SCLK has the arduino pin commented on, and that SPI_SSEL does not.

Now look at PinNames.h found at: /targets/TARGET_STM/TARGET_STM32F4/TARGET_STM32F401xE/TARGET_NUCLEO_F401RE/PinNames.h

You will notice that the default SPI_CS pin is PB_6 (as highlighted in the image below), which is not added to the PinMap in PerphiralPins.c. I have not checked whether other STM Nucleo boards have similar issues as well.

[brandonboesch]

@screamerbg

[0xc0170]

cc @bcostm @adustm @LMESTM @jeromecoutant

[jeromecoutant]

Hi
I agree this is misleading...
But I think there is no issue as in MBED, we are using SW NSS management.
So SPI_CS, connected to PB_6/D10, is used as a GPIO out.
The HW part (pins in PinMap_SPI_SSEL) are not really used...

As an example , you can see it in
https://github.com/ARMmbed/ci-test-shield/blob/master/TESTS/API/SPI/SPI.cpp#L54

[LMESTM]

@brandonboesch - one more question, are you facing an actual issue ?
Physically on the board the SPI HW NSS is indeed not connected to the PB6/D10 pin, so you actually have 2 possibilities

1. use SPI_CS as SW GPIO as done most of the time in MBED as explained by @jeromecoutant
   or
2. use another pin from the list in PinMap_SPI_SSEL table if you want to use SPI HW NSS.

[brandonboesch]

Thanks for the clarification. Using SPI_CS as SW GPIO will work fine for my purposes. Closing the issue.