52820 COMP interrupt problem

RE: 52820 COMP interrupt problem

Jørgen Holmefjord — Fri, 26 Feb 2021 13:56:53 GMT

If you look at the description and figures in the COMP peripheral documentation, you will see that this is not possible. VIN- will initially be set to either VUP or VDOWN, depending on if VIN+ is ABOVE or BELOW VIN-. The VIN- needs to cross VIN+ in the given direction before it switch to detecting crossing in the other direction.

So after the input have increased to 3.0V, you should be able to detect the down crossing if decreasing the input to 1.5V again.

RE: 52820 COMP interrupt problem

logan.xu — Fri, 26 Feb 2021 12:58:43 GMT

Hi，Jorgen,

I have another question. I set the threhold param as follow:

comp_config.threshold.th_down = NRFX_VOLTAGE_THRESHOLD_TO_INT(2.0, 3.3);
comp_config.threshold.th_up = NRFX_VOLTAGE_THRESHOLD_TO_INT(2.8, 3.3);

And if the VIN+ is 2.5V(above 2.0V) when call nrf_drv_comp_start(NRFX_COMP_EVT_EN_CROSS_MASK, 0), so the value of nrfx_comp_sample() is 1. When VIN+ increase from 2.5V to 3.0V, it won't generate interrupt. It only generate when VIN+ decrease from 2.5V to 1.5V(for example).

I hope it can generate interrupt both when increase above 2.8V and decrease bellow 2.0V. Does it possible?

RE: 52820 COMP interrupt problem

logan.xu — Fri, 26 Feb 2021 01:43:10 GMT

Thank you. As your suggestion, I mofify the define of nrfx_comp_irq_handler In nrfx_irqs_nrf52820.h, "#define COMP_LPCOMP_IRQHandler" to "#define COMP_IRQHandler", it works now.

RE: 52820 COMP interrupt problem

Jørgen Holmefjord — Thu, 25 Feb 2021 17:29:08 GMT

Since nRF52820 does not have a LPCOMP peripheral, there is no PRS box defined for sharing resources between COMP and LPCOMP. The interrupts from NVIC will be triggered directly in nrfx_comp_irq_handler (redefined from COMP_IRQHandler, which is the default handler name defined in the MDK files). In chips variants where both LPCOMP and COMP are available, and PRS is enabled, a common interrupt handler inside PRS is defined, where interrupts are forwarder instead of the default NRFX IRQ handler for that peripheral.

RE: 52820 COMP interrupt problem

logan.xu — Thu, 25 Feb 2021 07:25:15 GMT

Yes, prs_box_get will return NULL in current SDK code, and param irq_handler will not be used. So how can irq_handler be called when interrupt occured?

RE: 52820 COMP interrupt problem

Jørgen Holmefjord — Mon, 08 Feb 2021 10:06:23 GMT

Hi,

See my comment about PRS here. As far as I can see, the nrfx_prs_acquire() function should get a NULL-pointer returned from prs_box_get(), which should skip the if-setting and return success.

I tested your code (with some small modifications, replaced NRF_LOG with LED blinking, and connected a button as input, as I do not have a light sensor). I was able to generate interrupts (checked with debugger that event handler is called) by changing the state of the input pin. I did test on a nRF52833 DK with emulation for nRF52820,as I do not have a board with the actual chip available right now.

If your logging stops, it sounds like a hardfault or similar have occurred. This may have happened if you have configured the project incorrectly, or with wrong MDK files. If you could upload the full project, I can have a look at it.

Best regards,
Jørgen

RE: 52820 COMP interrupt problem

logan.xu — Mon, 08 Feb 2021 04:16:10 GMT

My develop SDK is 16.0.0(updated follow the link: https://devzone.nordicsemi.com/nordic/short-range-guides/b/getting-started/posts/developing-for-the-nrf52820-with-nrf5-sdk-v16-0-0). And there is no PRS NRF_COMP defined in nrfx_prs.h with SDK 17.0.2 too. Therefore, nrfx_comp_init -> nrfx_prs_acquire(NRF_COMP, nrfx_comp_irq_handler), the interrupte register fail.

RE: 52820 COMP interrupt problem

logan.xu — Sun, 07 Feb 2021 09:52:43 GMT

And I found that, in nrfx_prs.c, NRF_COMP not define for NRF52820.

#elif defined(NRF52820_XXAA)
// SPIM0, SPIS0, TWIM0, TWIS0, SPI0, TWI0
#define NRFX_PRS_BOX_0_ADDR NRF_SPIM0
// SPIM1, SPIS1, TWIM1, TWIS1, SPI1, TWI1
#define NRFX_PRS_BOX_1_ADDR NRF_SPIM1
// UARTE0, UART0
#define NRFX_PRS_BOX_2_ADDR NRF_UARTE0

#elif defined(NRF52832_XXAA) || defined(NRF52832_XXAB) || \
defined(NRF52833_XXAA) || defined(NRF52840_XXAA)
// SPIM0, SPIS0, TWIM0, TWIS0, SPI0, TWI0
#define NRFX_PRS_BOX_0_ADDR NRF_SPIM0
// SPIM1, SPIS1, TWIM1, TWIS1, SPI1, TWI1
#define NRFX_PRS_BOX_1_ADDR NRF_SPIM1
// SPIM2, SPIS2, SPI2
#define NRFX_PRS_BOX_2_ADDR NRF_SPIM2
// COMP, LPCOMP
#define NRFX_PRS_BOX_3_ADDR NRF_COMP
// UARTE0, UART0
#define NRFX_PRS_BOX_4_ADDR NRF_UARTE0