topic Re: KV5 TRACE_CLKOUT Divider in Kinetis Microcontrollers

KV5 TRACE_CLKOUT Divider

ohiogt — Thu, 21 Sep 2017 21:35:17 GMT

I'm using a MKV58 and observing the TRACE_CLKOUT. I found the divider enable in CLKDIV4 disables the output but the divisor appears to have no effect. I only see the fixed divide-by-2 applied to MCGOUTCLK. Are additional configuration steps required?

SIM->CLKDIV4 &= ~(SIM_CLKDIV4_TRACEDIV_MASK | SIM_CLKDIV4_TRACEFRAC_MASK);
SIM->CLKDIV4 |= (SIM_CLKDIV4_TRACEDIVEN_MASK | SIM_CLKDIV4_TRACEDIV(3U));

Re: KV5 TRACE_CLKOUT Divider

miduo — Tue, 26 Sep 2017 08:37:55 GMT

Hi,

The Trace clock depends on two clock sources - MCGOUTCLK and Core/system in SIM_SOPT2[TRACECLKSEL]. The trace clock divider setup in SIM_CLKDIV4[TRACEFRAC,TRACEDIV]. The TRACE_CLKOUT pin will be at maximum half of the selected clock source.

Re: KV5 TRACE_CLKOUT Divider

ohiogt — Tue, 26 Sep 2017 21:07:59 GMT

Fang,

I understand the basic operation, my issue is that the divisor and frac settings appear to have no effect on the clock output. Do you have any information on this?

Shawn