RTC in nrf52832

RE: RTC in nrf52832

Susheel Nuguru — Mon, 29 May 2023 09:20:44 GMT

Glad I could help, If there is nothing else regarding this context, can you please mark this thread verified so that it could help other searching for similar issues.

RE: RTC in nrf52832

Lurn_Z — Fri, 26 May 2023 07:11:24 GMT

Thanks for your reply.

RE: RTC in nrf52832

Susheel Nuguru — Fri, 26 May 2023 07:09:32 GMT

Then all the PPI channels below 20 are available to use which are not used for ESB.

RE: RTC in nrf52832

Lurn_Z — Fri, 26 May 2023 05:51:37 GMT

No, I didn't use the softdevice, I used ESB and UARTE, and I only know which channels the ESB uses.

RE: RTC in nrf52832

Susheel Nuguru — Fri, 26 May 2023 05:42:27 GMT

If you are using Softdevice/Thread/Zigbee stack then you need to check the "resource requirement" chapter of those protocols to see which PPI channels are reserved for the protocol stack. The FreeRTOS port does not use any PPI channels. Are you using any Softdevice?

RE: RTC in nrf52832

Lurn_Z — Fri, 26 May 2023 01:19:11 GMT

[quote userid="6207" url="~/f/nordic-q-a/99839/rtc-in-nrf52832/427572"]Not sure what you mean here, in the code snippet you used two difference channels of PPI,[/quote]

I means if I want to use more channels, how can I be sure that these channels are available (not used by others)?

RE: RTC in nrf52832

Susheel Nuguru — Thu, 25 May 2023 14:46:00 GMT

[quote user="Lurn_Z"]Q1:Since I want to use multiple PPI channels, how do I get the PPI channels that I can use?[/quote]

Not sure what you mean here, in the code snippet you used two difference channels of PPI, CH[0] and CH[1].

[quote user="Lurn_Z"]

Q2:

Could I use this code to trigger the same IRQ ?

[/quote]

Yes, the code makes any of the below events to trigger EGU3_IRQ and will assert the relevant event in EGU3

NRF_RTC0->EVENTS_COMPARE[0] -> triggers EGU3->EVENTS_TRIGGERED[0]
NRF_RTC0->EVENTS_COMPARE[1]; -> triggers EGU3->EVENTS_TRIGGERED[1]

RE: RTC in nrf52832

Lurn_Z — Thu, 25 May 2023 01:55:22 GMT

Hi Susheel,

Q1:Since I want to use multiple PPI channels, how do I get the PPI channels that I can use?

Q2:

Could I use this code to trigger the same IRQ ?

    NVIC_SetPriority(SWI3_EGU3_IRQn, 6);
    NVIC_EnableIRQ(SWI3_EGU3_IRQn);

    NRF_EGU3->INTENSET = EGU_INTEN_TRIGGERED0_Msk;

    NRF_PPI->CH[0].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[0];
    NRF_PPI->CH[0].TEP = (uint32_t)&NRF_EGU3->TASKS_TRIGGER[0];
    
    NRF_PPI->CH[1].EEP = (uint32_t)&NRF_RTC0->EVENTS_COMPARE[1];
    NRF_PPI->CH[1].TEP = (uint32_t)&NRF_EGU3->TASKS_TRIGGER[0];

Best regards,

Lurn

RE: RTC in nrf52832

Lurn_Z — Wed, 24 May 2023 08:09:04 GMT

Thanks for your explanation.

RE: RTC in nrf52832

Susheel Nuguru — Wed, 24 May 2023 08:06:51 GMT

you do not need to restart it. The RTC is still running when you clear the counter, so it continue counting just that the counter is cleared.

RE: RTC in nrf52832

Lurn_Z — Wed, 24 May 2023 07:39:00 GMT

And also I don't need to restart it? use NRF_RTCn->TASKS_START = 1.

I see, thanks a lot.

RE: RTC in nrf52832

Susheel Nuguru — Wed, 24 May 2023 07:35:55 GMT

No, only the counter value is cleared and the rest of the configuration should stay intact. So the timeout your configured in CC should become periodic after this short with PPI is enabled.

RE: RTC in nrf52832

Lurn_Z — Wed, 24 May 2023 05:24:55 GMT

After clear the tasks should I reconfigure it?

RE: RTC in nrf52832

Susheel Nuguru — Wed, 24 May 2023 04:30:57 GMT

Please write 1 to NRF_RTCn->TASKS_CLEAR

 NRF_RTCn->TASKS_CLEAR = 1;

RE: RTC in nrf52832

Lurn_Z — Wed, 24 May 2023 03:21:00 GMT

Hi Susheel,

Can I reset the RTC and make the NRF_RTCn->COUNTER to zero?

How to do this?

Best regards,

Lurn

RE: RTC in nrf52832

Lurn_Z — Wed, 24 May 2023 01:07:24 GMT

Hi,

I didn't configure the RTC2 CC, the RTC2 is used to count.

And since I didn't know how to run it auto on ISR at first so I change it to PPI, and now it looks good.

Thanks.

Best regards,

Lurn

RE: RTC in nrf52832

Susheel Nuguru — Tue, 23 May 2023 18:11:35 GMT

I am not sure what you configured RTC2 with CC value? I can only see RTC0 configuration.

Instead of clearing the event and starting the RTC START tasks, you can use a PPI to connect this event to the tasks_clear. Why rely on the variable ISR completion time when you can configure PPI to make this very predictable in terms of timing.

RE: RTC in nrf52832

Lurn_Z — Tue, 23 May 2023 07:47:59 GMT

Hi,

Thanks for your reply.

Q1.

[quote userid="6207" url="~/f/nordic-q-a/99839/rtc-in-nrf52832/426756"]Maybe you should add some code like below to connect event to clear the counter in rtc_config[/quote]

I can't understand you about this, what did you mean about the below? Is what I did in IRQ handler or you just forget include the code?

The information I found says the RTC didn't have the SHORTS like TIMER, so we have to config it after the interrupt.

And like I said, I can use PPI to do this.

Q2,

I will try it to start both RTC at the same time.

Best regards,

Lurn

RE: RTC in nrf52832

Susheel Nuguru — Tue, 23 May 2023 07:13:41 GMT

Hi,

Thanks for your patience during our holiday period.

[quote user=""]1. after the RTC0 interrupt triggered, the RTC0 will not run to next interrupt auto, so I have to do this. How to modify the config can make it continue trigger auto?[/quote]

If you want a periodic timer using RTC, then once you have your interrupt triggered when CC value matches the counter, then you should clear the RTC counter value, so that the RTC start counting again from the start. Maybe you should add some code like below to connect event to clear the counter in rtc_config

[quote user=""]2. In IRQ handle I print the RTC count, and I think the value should be ((2000 * 32768)/ 1000000U)= 65.[/quote]

I would suggest you to start both RTC instances at the same time like below.

NRF_RTC0->TASKS_START = 1;
NRF_RTC2->TASKS_START = 1;

Also, it depends on how and when you are capturing the RTC counter values. If the reads for these two instances can be interrupted by some other higher priority contexts, then you can see some differences in the two counter values.

RE: RTC in nrf52832

Menon — Fri, 19 May 2023 11:32:56 GMT

Hello,
I am sorry, but we are short staffed this week due to Public Holidays in Norway. We will be back on Monday 22nd and hope to be able to answer all incoming requests within a couple of days, depending on the backlog. I am sorry for the inconvenience.

Best regards,
Abhijith

RE: RTC in nrf52832

Lurn_Z — Fri, 19 May 2023 08:11:43 GMT

I solved it with PPI but still don't know why it doesn't work automatically.

    NVIC_SetPriority(SWI3_EGU3_IRQn, 6);
    NVIC_EnableIRQ(SWI3_EGU3_IRQn);
    NRF_EGU3->INTENSET = EGU_INTEN_TRIGGERED0_Msk;

    NRF_PPI->CH[0].EEP = (uint32_t) &NRF_RTC0->EVENTS_COMPARE[0];
    NRF_PPI->CH[0].TEP = (uint32_t) &NRF_EGU3->TASKS_TRIGGER[0];

    NRF_PPI->FORK[0].TEP = (uint32_t) &NRF_RTC0->TASKS_CLEAR;

    NRF_PPI->CHENSET = PPI_CHENSET_CH0_Msk;