Linker error when merging twi-examples into ble_app_uart

RE: Linker error when merging twi-examples into ble_app_uart

Pero Krivic — Wed, 16 Mar 2022 10:23:01 GMT

Awesome, thanks for the explanation.

RE: Linker error when merging twi-examples into ble_app_uart

Jared — Wed, 16 Mar 2022 10:01:38 GMT

Hi,

The TWI scanner example in the SDK is built to be run in blocking mode. The function will return a NRF_SUCCESS only if it finds a slave on the bus and the transfer is successful.

However, if the driver is used in non blocking mode, then the function will return immediately, before the transfer has finished with a NRF_SUCCESS. It will then eventually generate a nrf_drv_twi_evt_type_t event that indicates if the transfer was successful or not.

Because the function returns immediately with NRF_SUCCESS in non-blocking mode, the example code will interpret this as a device has been found on the address.

regards

Jared

RE: Linker error when merging twi-examples into ble_app_uart

Pero Krivic — Tue, 15 Mar 2022 19:29:02 GMT

Hi, I have added a dummy handler function like this:

/**
 * @brief TWI events handler.
 */
void twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context)
{
    switch (p_event->type)
    {
        case NRF_DRV_TWI_EVT_DONE:
            if (p_event->xfer_desc.type == NRF_DRV_TWI_XFER_RX)
            {
               NRF_LOG_INFO("\n\rTWI Data handler");
               NRF_LOG_FLUSH();
            }
            //m_xfer_done = true;
            break;
        default:
            break;
    }
}

Then if I make my init function like this:

nrf_drv_twi_init(&m_twi, &twi_config, &twi_handler, NULL);

the twi_scanner example finds a device at every address.But if I exlude the handler pointer, like this:

nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);

it works fine again.

Why is that so?

RE: Linker error when merging twi-examples into ble_app_uart

Jared — Tue, 15 Mar 2022 08:38:22 GMT

Hmm, I can't see how that would make any difference. Not providing a handler to the initialize function means the driver will be configured in blocking mode.

RE: Linker error when merging twi-examples into ble_app_uart

Pero Krivic — Mon, 14 Mar 2022 13:08:12 GMT

Hi Jared, thanks for the reply.

I am using nRF52-DK, unmodified, so everything shoud be as shipped.

[quote userid="73165" url="~/f/nordic-q-a/85779/linker-error-when-merging-twi-examples-into-ble_app_uart/357941#357941"]Is your code based on twi_sensor or tw_scanner? [/quote]

I have tried both. For the clarity, the last time I was testing the setup, i used twi_scanner (which retourned positive for every address it has scanned).

Best,

EDIT: hello, the issue seems to have been solved when the handler is excluded from the twi_init function, that is if the init is called like this:

err_code = nrf_drv_twi_init(&m_twi, &twi_lm75b_config, NULL, NULL);

now the scanner works and no twi device is detected, as it should be. Originally, I had the handler address sent to init function (leftover from twi_sensor example).

Why is that so? Why the scanner example makes trouble if the handler address is passed through?

RE: Linker error when merging twi-examples into ble_app_uart

Jared — Mon, 14 Mar 2022 12:40:22 GMT

Hi,

If it builds fine without any errors, then I think we can assume that everything is included for it to work. The culprit might be related to something else.

[quote user=""] the scanner application returned true for every address probed (but obviously there should be no devices present).[/quote][quote user=""]copied the main.c code from twi_sensor into my main.c[/quote]

Is your code based on twi_sensor or tw_scanner?

What pin are you using for the SDA line and is it connected to something externally? Do you get the same result if you connect the pin to VDD?

regards
Jared