topic KE18 ADC hardware trigger in Kinetis Microcontrollers

KE18 ADC hardware trigger

davidsherman — Mon, 15 Oct 2018 20:05:03 GMT

I can't seem to get the ADC to trigger from the LPIT or the FTM using the TRGMUX. The ADC works from software triggers. I can confirm the LPIT is running and it is triggering events, but I can't get the ADC interrupt to happen on any of the channels. I have the pseudocode example in the KE18 manual implemented, but nothing happens.

SIM->ADCOPT |= SIM_ADCOPT_ADC0TRGSEL(1) | SIM_ADCOPT_ADC0PRETRGSEL(1);

TRGMUX0->TRGCFG[TRGMUX_ADC0_INDEX] = TRGMUX_TRGCFG_SEL0(0x07); // use LPIT ch0 for trigger source

ADC0->SC2 |= ADC_SC2_ADTRG(1);

What am I missing? Unfortunately, the ADC chapter is confusing on the subject of pretriggers and triggers. I'm just trying to get the ADC to trigger at a regular interval.

Re: KE18 ADC hardware trigger

xiangjun_rong — Tue, 16 Oct 2018 07:23:09 GMT

Hi, David,

I think your above code is correct, can you post your code here so that we can have a review and debug?

Xiangjun Rong

Re: KE18 ADC hardware trigger

davidsherman — Tue, 16 Oct 2018 14:43:59 GMT

I found it, I missed the part in the LPIT where it has to be stopped to change the interval. I was modifying something that did software triggers, but part of it calculates the acquisition interval and it stopped the LPIT when it tried to update the interval. Seems to be working now.