S32K中的主题 select clock for modules with PCC?

select clock for modules with PCC?

JeorgeB — Sat, 21 Nov 2020 13:11:43 GMT

Hi,

I wanna to use LPSPI. assume there is a SOSC and Core CLK is 80MHz. bus clock is 40MHz. FIRC is 48MHz.

Can I use FIRC as input clock for LPSPI module ? (it is bigger than BUS CLK)

in page 566 for LPSPI, RM says : "Maximum frequency governed by BUS_CLK"

Thanks.

Re: select clock for modules with PCC?

Robin_Shen — Mon, 23 Nov 2020 02:07:15 GMT

Hi JeorgeB,

You can not use FIRC(48MHz) as input clock for LPSPI module as it is bigger than BUS_CLK(40MHz).

Best Regards,
Robin
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Re: select clock for modules with PCC?

JeorgeB — Mon, 23 Nov 2020 04:53:32 GMT

Hi Robin, A. what is BUS_CLK role in here? is it only for communication between Master and the module? B. If we gated off this clock [CGC], the module will be switched off (do not consume power)? or we should disable [PCS] clock? C. Assume we, use prescaler and SCK divider with register appropriate setting, and LPSPI SCK clock is 8MHz, is there same limitation by using FIRC-48MHZ? Thanks.

Re: select clock for modules with PCC?

Robin_Shen — Wed, 25 Nov 2020 08:15:31 GMT

C. The limitation is for Functional clock, not the clock after divider. Same limitation by using FIRC-48MHz (>40MHz BUS_CLK)