I want to communicate with STM32f427 processor and 3 sensors via SPI. I want to use only SPI1 line. I need 3 chip select pins. There are 2 SPI1_NSS pins on the datasheet of the processor. What can I use as 3 CS pins? Is any GPIO pin suitable?
YES, all the nCS signal in SPI SW mode - generate the nCS signals yourself (via toggling GPIOs). Works fine (I use it).
Bear in mind: you can (should) use nSS (nCS) in SW mode: you cannot use the intended SPI nSS HW signal in HW mode (it would toggle all the time with a new SPI transaction). All nCS signals are now a GPIO signal. You can use the intended GPIO (pin) for nSS also in GPIO mode: just make sure you do not configure all the nSS signal as SPI nSS signal (instead as a GPIO).
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