topic S32K144 - ADC how to use more than 8 channels in S32K

S32K144 - ADC how to use more than 8 channels

arkadyosh — Thu, 12 Jan 2017 07:35:43 GMT

Hi,
Start conversion by software trigger is only possible to SC1A, to use rest of SC1n need to use for example PDB but its can trigger max 8 channels. How to use more than 8 channels by one ADC? It is possible or I need to use ADC0 and ADC1 to get more than 8 ADC channels?

Re: S32K144 - ADC how to use more than 8 channels

PetrS — Tue, 17 Jan 2017 14:31:56 GMT

Hi Arkadiusz,

There are 2 PDB modules on this device. Each PDB module has two ADC trigger channels (each ADC channel with 8 pre-triggers). So the PDB0 can start up to 16 conversions on ADC0, the PDB1 then also 16 conversions on ADC1.

BR, Petr

Re: S32K144 - ADC how to use more than 8 channels

arkadyosh — Thu, 19 Jan 2017 07:02:20 GMT

Thanks for your reply Petr.
I miss in some way the second channel... I have next question, how to trigger the second channel after first complete? Can it be start without software intervention? I think I can use CH1DLY0 to start second channel after some delay or there is a better way?

Regards,

Arkadiusz

Re: S32K144 - ADC how to use more than 8 channels

PetrS — Fri, 20 Jan 2017 15:18:41 GMT

Hi Arkadiusz,

Either you can program a delay for each pre-trigger with a help of PDB channel’s DLY register or you can use the back-to-back operation.

For a first case upon external trigger or SW start the PDB counter will start counting from zero to MOD value. The pre-trigger asserts when the counter is equal to DLY value. Thus you need to set the counter modulo and channels pre-triggers delay according to ADC conversion time, so the ADC will finish single conversion before next trigger came.

The back-to-back operation enables the ADC conversions complete to trigger the next PDB channel pre-trigger and trigger output. Consult a RM for a possible back-to-back chain implementation.

BR, Petr