nRF52 DK & PCA9685 (TWI bug)

RE: nRF52 DK & PCA9685 (TWI bug)

Nur2705 — Tue, 29 Jun 2021 07:47:33 GMT

Hi, Jared

I found the problem
It was not in TWI, but in the fact that my functions were losing their data.
All the code I wrote didn't work as intended. I suspect the problem is in the compiler. Should I ask a new question or continue the discussion here?

RE: nRF52 DK & PCA9685 (TWI bug)

Nur2705 — Sat, 19 Jun 2021 13:56:55 GMT

Earlier, I collected code with a flag, but it periodically did not exit the loop.

Maybe I had a mistake there. I will try to collect again next week using a so far loop.
Thank you for your help.

If necessary, I will inform you about the results.

RE: nRF52 DK & PCA9685 (TWI bug)

Jared — Fri, 18 Jun 2021 13:41:46 GMT

Ok, I didn't see this part in the code that you shared earlier. Anyways, what do you observe now? Any difference? Is the flag set? What does the function call return?

RE: nRF52 DK & PCA9685 (TWI bug)

Nur2705 — Fri, 18 Jun 2021 13:11:33 GMT

I checked the flag immediately after transmission

    m_xfer_done = false;
    nrf_drv_twi_tx(&m_twi,PCA9685_ADDRESS,buff, sizeof(buff), false);
    while (m_xfer_done == false);

RE: nRF52 DK & PCA9685 (TWI bug)

Jared — Fri, 18 Jun 2021 13:07:25 GMT

Where do you check the flag before a new transfer is performed?

RE: nRF52 DK & PCA9685 (TWI bug)

Nur2705 — Fri, 18 Jun 2021 12:51:33 GMT

Hi, Jared

I also used a flag, but I am afraid of the possibility that the callback may not work.

RE: nRF52 DK & PCA9685 (TWI bug)

Jared — Fri, 18 Jun 2021 12:42:39 GMT

Hi,

Could describe exactly what happens if you omit the delay and how it's not what you expected it to be?

It seems like you're not checking the return value from the nrf_drv_twi functions, which you should so we could understand what exactly the issue is.

For example:

    err_code = nrf_drv_twi_tx(&m_twi, slave_addr, reg, 1, false);
    APP_ERROR_CHECK(err_code);

My guess is that driver returns NRF_ERROR_BUSY without the delays, as you're not using any flag to signalize when the driver is finished with a transfer. I would suggest that you take a look at your twi_sensor example in the SDK, it uses a flag to signalize that the driver is ready for a new transfer.

best regards

Jared