Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

RE: Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

ovrebekk — Fri, 28 Jan 2022 14:22:18 GMT

Any project you build in Zephyr will have the Zephyr RTOS running underneath, and this affects how interrupts should be configured.

Essentially interrupts in Zephyr can be set up like this:

IRQ_DIRECT_CONNECT(RTC0_IRQn, 0, my_rtc0_irq_handler, 0);
irq_enable(RTC0_IRQn);

More information about the IRQ_CONNECT and IRQ_DIRECT_CONNECT macros can be found here.

Best regards
Torbjørn

RE: Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

Abir Hossain — Thu, 27 Jan 2022 17:32:28 GMT

Thanks for the reply both ovrebekk and hmlesworth. I will try this changes too.
But I think it is more of a project setup issue.

I tried similar code on uVision and working fine. I am using Vscode and used an example Zphyre project as templete. So My guess is some components/config from Zphyre is conflicting with my attempt to make project baremetal. Thats why added the project here.

Thanks

RE: Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

Abir Hossain — Thu, 27 Jan 2022 17:31:36 GMT

RE: Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

Abir Hossain — Thu, 27 Jan 2022 17:27:58 GMT

The board is nrf52-DK, nrf52832, official board
devzone.nordicsemi.com/.../basic_2D00_timer.zip

RE: Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

hmolesworth — Thu, 27 Jan 2022 16:16:13 GMT

Try this and also init the i/o pin before enabling the timer:

/ This IRQ handler will trigger every 30.5 ms
void RTC0_IRQHandler(void)
{
  if (NRF_RTC0->EVENTS_COMPARE[0] == 1)
  {
    NRF_RTC0->EVENTS_COMPARE[0] = 0;
    // COUNTER and COMPARE[n] registers are all 24-bit. It seems an intermediate sampled
    // value must be used as pRTC->CC[IDX_SYS_TICK] += N; does not work for some reason,
    // maybe requires so many cycles to read back and CountValue must be synchronous (unchanging)
    //  - COUNTER register read takes a fixed 5 x PCLK16M clock cycles
    volatile uint32_t CountValue = NRF_RTC0->COUNTER;
    // Increment compare value with 30.5 ms from current time.
    NRF_RTC0->CC[0] = CountValue + 1000;
    // Data Synchronization Barrier: completes when all explicit memory accesses before
    // last instruction completes to avoid spurious interrupt
    __DSB();
  }
}

RE: Nrf52 simple Baremetal timer function, CPU reset if interrupt enabled.

ovrebekk — Thu, 27 Jan 2022 10:01:34 GMT

Hi Abir

If you don't use a SoftDevice I don't know why this code would cause a crash.

Can you let me know what kind of hardware you are testing on?

Is it a standard DK, or some other kind of board?

If you can upload the entire project that would be great, then I can easily test it here. It should be enough to drag drop a file into your reply if you want to attach files.

Best regards
Torbjørn