nRF52840 - Configure TWI pins on PORT1

[Bilal Bouguerra]

Hello,

I am currently working on a custom nRF52840 board. I have to make the nRF52 communicate with a chip using TWI, so I started from SDK 15.2.0 TWI Scanner example.

The pinout is the following:

- SCL: P1.09

- SDA: P0.12

To make the TWI driver work with PORT1 gpios I used the macro NRF_GPIO_PIN_MAP:

/**
 * @brief TWI initialization.
 */
void twi_init (void)
{
    ret_code_t err_code;

    const nrf_drv_twi_config_t twi_config = {
       .scl                = NRF_GPIO_PIN_MAP(1, 9),
       .sda                = NRF_GPIO_PIN_MAP(0, 12),
       .frequency          = NRF_DRV_TWI_FREQ_400K,
       .interrupt_priority = APP_IRQ_PRIORITY_HIGH,
       .clear_bus_init     = false
    };

    err_code = nrf_drv_twi_init(&m_twi, &twi_config, NULL, NULL);
    APP_ERROR_CHECK(err_code);

    nrf_drv_twi_enable(&m_twi);
}

But when I run the application, the execution is stuck in this loop of nrfx_twim.c starting from line 441:

while (!nrf_twim_event_check(p_twim, evt_to_wait))
{
    if (nrf_twim_event_check(p_twim, NRF_TWIM_EVENT_ERROR))
    {
        NRFX_LOG_DEBUG("TWIM: Event: %s.", EVT_TO_STR_TWIM(NRF_TWIM_EVENT_ERROR));
        nrf_twim_event_clear(p_twim, NRF_TWIM_EVENT_ERROR);
        nrf_twim_task_trigger(p_twim, NRF_TWIM_TASK_RESUME);
        nrf_twim_task_trigger(p_twim, NRF_TWIM_TASK_STOP);
        evt_to_wait = NRF_TWIM_EVENT_STOPPED;
    }
}

Can you please tell me what I am doing wrong and what to do to make TWI work with PORT1 gpios ?

Thank you very much !

Bilal

[haakonsh]

What's the state of the TWIM registers when your stuck waiting for the evt_to_wait (NRF_TWIM_EVENT_STOPPED)?

[Bilal Bouguerra]

Please find below a screenshot of the state of TWIM registers when my program is stuck:

Also all the tasks from STARTRX to RESUME are false.

Does the TWI support PORT1 gpios ?

Kind regards

Bilal

[haakonsh]

"Does the TWI support PORT1 gpios ?"

Yes, see PSEL.SCL

1. Do you enter the if (nrf_twim_event_check(p_twim, NRF_TWIM_EVENT_ERROR)) statement?
   
2. Do you have a scope of the communication?
   
   
3. Can you share the relevant code?

[Bilal Bouguerra]

1. I have put a breakpoint and I observe that I dont enter this statement.

2. I don't have a scope of the communication but I will see if I can put in place a trafic analyzer as soon as possible.

3. The code is the same as twi_scanner_pca10056 except for the twi initialization, I only changed these three lines:

.scl                = NRF_GPIO_PIN_MAP(1, 9),
.sda                = NRF_GPIO_PIN_MAP(0, 12),
.frequency          = NRF_DRV_TWI_FREQ_400K,

[haakonsh]

1. If it's not an error then the TWIM is waiting for a trigger, most likely an ACK/NACK, release of SDA line, or something like that.
2. We really need that scope to see what's going on.
   
   
3. I do not see anything wrong with that configuration.