PPI ADC + Timer usage

RE: PPI ADC + Timer usage

Hieu — Thu, 09 Jan 2025 20:56:05 GMT

Hi hugh512,

First, I want to make sure we are on the same page that the DevAcademy exercise you linked described the steps to create a TIMER, SAADC, and PPI setup that runs automatically indefinitely, with only a manual trigger setup once at the beginning.

Now regarding your requirement, I see here that you want to use two analog inputs.

Is it possible to instead scan both these inputs in 65 cycles, each cycle sample AIN1 once and then AIN2 once?
The reason is because if you enabled more than one SAADC channel, the device enters Scan Mode, and each sample task will sequentially sample all enabled channels.

If that is not possible, and you strictly need to sample AIN1 alone 65 times, before sampling AIN2 alone 65 other times, then you will have to reconfigure the entire setup manually.

To reconfigure it, you don't need to use the EGU. It's best to just do it in the SAADC event handler. The reconfiguration should be reasonably short enough to do there.

Does this answer your questions?

RE: PPI ADC + Timer usage

hugh512 — Mon, 06 Jan 2025 15:06:16 GMT

Sorry, I didn't describe my requirements clealy.
My requirement is:

|----------------------------cycle1-------------------------------------||----------------------------cycle2-------------------------------------|
|3ms delay|AIN1 sample 65 times|AIN2 sample 65times| |3ms delay|AIN1 sample 65 times|AIN2 sample 65times|

In each cycle:
I want to use PPI to do ADC sampling, so I need to trigger sample manuall.
I checked the specification, This is a module named "EGU", I'm not sure if it can be used to trigger ?

RE: PPI ADC + Timer usage

Naeem Maroof — Thu, 02 Jan 2025 21:33:08 GMT

Hello,

Were you able to see the output as per exercise? And now you want to make some modifications?

Do you mean you want to trigger the timer once, or twice?

What do you mean by "manually" trigger timer? Do you intent NOT using PPI?

The exercise you have referred to uses the SAADC driver to measure voltage and uses a hardware TIMER to trigger sampling through DPPI/PPI, without any CPU involvement. Do you still want to use the PPI or Not?

At the top, you can see the sampling interval is set as 50us. You can change that.

In the configure_timer function, timer channel0 is used for extended mode. You can use other channels like channel0 is used.