Do I need to use the PCS0 pin to activate the SPI in slave mode?

[marcohess]

I am using a K22FN on a custom board where I am interfacing SPI1 in slave mode to some SPI 'like' master device.

This device does not generate a chip select signal. Instead it uses two I/O signals. One to signal the start of a new cycle and one to signal the start of new 16 bit word transfer after which the clock starts for the data transfer.

As such I had not connected the PCS0 input and instead configured that pin as a general I/O.

However, I can't seem to get my device to transmit anything in slave mode.

Does the PCS0 need to be used? Or can I set it to enabled in software? If not, can I tie the pin to a fixed level?

[jeremyzhou]

Hi Marco,

I guess that you must use the PCS0/SS pin when you want the K22 works as slave device.

In Slave mode, the SPI module respons to externally controlled serial transfer. The SCK signal and the PCS0/SS signals are configured as input and driven by an SPI bus master.

Wish it helps.
Have a great day,
Ping

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