Pull-ups requirement for SPI Chip select pin of MK70FN1M0VMJ12

[puspamnayak]

Hello,

I am using CS0, CS1 and CS2 of SPI for communicating with slave devices. Want to know do i need to connect pull-ups on chip select pins. If Yes then what is the recommended Pull-Up values

Kindly reply ASAP

Regards,

Puspam N

[egoodii]

A pull-up on SPI CS pins is 'generally recommended', but specifically because at power-up the chosen Kinetis pins will be floating, and not 'in control'.  Once turned to their SPI CS function, they will be actively driven at all times.  The recommended value (ideally) depends on 'worst case' leakage into pins, but a plain ol' rule-of-thunb for CMOS is 10K.