topic Re: S32K148 - FTM and external clock in S32K

S32K148 - FTM and external clock

jakub_mielczare — Mon, 23 Mar 2020 11:21:06 GMT

Hello,

In my application I need to use FTM timer in S32K148. I have the following questions:

1. Can FTM sue 24.576MHz clock as EXTCLK

2. There are TCLK0-2 inputs for EXTCLK. Which input can be used by which FTM timer instance?

NEW QUESTIONS:

3. Can FTM timer in output compare mode be clocked (EXTCLK) by clock which is not 50% duty cycle?

4. What is the minimum duty cycle in this case?

5. What is the minimum pulse width in this case?

Best regards,

Jakub

danielmartynek — Wed, 25 Mar 2020 12:57:41 GMT

Hello Jakub,

As you can see in the RM,

The external clock must not exceed 1/4 of FTM input clock (SYS_CLK).

TCLKn for each FTMn can be selected in the SIM_FTMOPT0 register.

It can be used in OC mode.

4 & 5.

It is not specified.

But the restriction also considers jitter.

Regards,

Daniel