8 years, 1 month ago.

Logic of PeripheralPins.c

While trying to understand some problems i am having using spi on a custom board based on NucleoF401RE, i turned back to nucleo and found something for which i am not sure anymore. On NucleoF401RE i see printed on board on the right side on pin D10 following text "PWM/CS/D10". So i can use that pin to connect the chip select and this is also working good but looking at the file:

https://developer.mbed.org/users/mbed_official/code/mbed-dev/file/156823d33999/targets/TARGET_STM/TARGET_STM32F4/TARGET_NUCLEO_F401RE/PeripheralPins.c

pin D10 (which is PB_6 based on https://developer.mbed.org/platforms/ST-Nucleo-F401RE/) is listed under the arrays PinMap_I2C_SCL, PinMap_PWM and PinMap_UART_TX but is not listed under PinMap_SPI_SSEL. So first question (1) how can this pin be used as chip select, shouldn't it be listed under PinMap_SPI_SSEL to be used as chip select, i.e. it works but why does it work?

That leads me to the second question: (2) if i have a custom board and want to use for example pin PB_12 for AnalogIn than should i add PB_12 to PinMap_ADC array as follows?

PinMap PinMap_ADC[] = {
....
    {PB_12, ADC_1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 0,  0)},
...
}

(3) Should i also remove it from the array where its declared now PinMap_SPI_SSEL?

Thanks for the help.

EDIT

I tried to to build mbed with the following changes in PeripheralPins.c: i commented the line PB_12 in PinMap_SPI_SSEL and added

{PB_12, ADC_1, STM_PIN_DATA_EXT(STM_MODE_ANALOG, GPIO_NOPULL, 0, 19, 0)}, 

into the PinMap_ADC.

Building mbed worked fine but i still could not use that pin for AnalogIn using the examples under https://developer.mbed.org/handbook/AnalogIn. Should i change anything else or am i in the wrong path?