TMS570LC4357: ADC Single conversion triggered from PWM Module

Hi,

Each PWM module has two ADC start of conversion signals: SOCA and SOCB. Did you enable ePWMxSOCA or ePWMxSOCB?

You can use HALCOGen GUI to enable it:

Hi yes, SOCB is enabled and I can see the SOB status flag being set every cycle when trigger occurs. I think it is something to do with Pinmuxing.

one more question, do I need to set the ADC channels as input pin or when selecting ADC channels in HALCOGen it automatically does that?

Hi Ali,

All the ADC pins except for EVT pins are input pins. It is not configurable. 

Please double check if etpwmStartTBCLK() is called in your code.

Yes, the PWM block is started and I can now see the trigger is being generated and ADC scans the result however after the first sample the ADC data register is not updating at all even though I have checked the trigger is being sent every PWM cycle.

I am reading data directly from ADC ram and not from FIFO could that be an issue. 

So I think the trigger is being sent but ADC is not scanning the port after the 1 cycle.

I have configured ePWM4 SOCB to send trigger to ADC and on ADC side I have set the pin mux as shown in above snapshot 

still on trigger happens onces only

PinMux

Hi QJ Wang,

So I got my head around and got the ADC working with setting override RAM data bit to 1

Now I have continuous data update after every PWM trigger cycle. The question I have now is if I leave the override RAM data bit to 0 then how do I clear the ram so that new results are written in the next cycle.

Thanks,

Ali

If OVR_RAM_IGN = 1, the ADC module overwrites the group’s results’ memory contents with new conversion results.

If OVR_RAM_IGN = 0, the application program has to read out the group’s results’ memory upon an overrun condition; only then can the ADC continue to write new results to the memory.