How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

RE: How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

Mahaliana — Fri, 23 Dec 2016 15:31:23 GMT

About the addressing, the problem came from the pin connectors.
About the write, I had to transmit the reg address and the data in one line. Thanks a lot for your help.

RE: How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

bjorn-spockeli — Tue, 20 Sep 2016 08:18:05 GMT

@mahaliana : Could you try to set a flag in the twi_event_handler when you get the NRF_DRV_TWI_TX_DONE event, i.e.

void twi_handler(nrf_drv_twi_evt_t const * p_event, void * p_context) 
{ 
   switch(p_event->type) { 
      case NRF_DRV_TWI_RX_DONE: 
      m_xfer_done = true;
      break; 
   default: 
      break; 
  } 
}

and then initiate a twi transaction like this

m_xfer_done = false; 
ret_code = nrf_drv_twi_rx(&p_twi_instance, start_byte, &start_byte, 1, false); 
while(!m_xfer_done){//do nothing}

This way you will wait until the TWI transaction is finished before starting the next one.

RE: How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

Mahaliana — Mon, 12 Sep 2016 13:32:46 GMT

Thank you for your answer. Yes, I am using that but it does not solve my problem. Please look above, I edited the original post to give more details.

RE: How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

bjorn-spockeli — Mon, 05 Sep 2016 08:17:14 GMT

Are you using the TWI driver(nrf_drv_twi) from SKD v9.0.0 in SDK v8.0.0? If that is the case, then the following code

uint8_t address = 0x77; ret_code = nrf_drv_twi_tx(&p_twi_instance, address, &press_reg, 1, true);

should result in the NRF_DRV_TWI_TX_DONE

RE: How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

Mahaliana — Fri, 02 Sep 2016 14:28:56 GMT

At the beginning, I followed what was told in this link : link text

So the code where I initialize the TWI driver is :

ret_code_t ret_code;

const nrf_drv_twi_t     p_twi_instance = NRF_DRV_TWI_INSTANCE(1); 
nrf_drv_twi_config_t    p_twi_config = NRF_DRV_TWI_DEFAULT_CONFIG(1);
ret_code = nrf_drv_twi_init(&p_twi_instance, &p_twi_config, twi_event_handler); 
APP_ERROR_CHECK(ret_code);  
nrf_drv_twi_enable(&p_twi_instance);

I tried what you adviced me but the result is the same, i.e. error event is generated. And what I wanted to explain was that I had to pass through the slave_address 0x76 (the front 0x77) by using the for loop, as shown in the first code. I can't obtain directly a TX_SENT or a RX_READY by passing through the slave_address 0x77 the first time.

Thank you

RE: How to access to the slave address and to manage successive nrf_drv_twi_tx() ?

bjorn-spockeli — Fri, 02 Sep 2016 11:39:19 GMT

Could you post the code where you initialize the TWI driver, i.e. nrf_drv_twi_init?1

1) You mean that you cannot call nrf_drv_twi_txthe following way

nrf_drv_twi_tx(&p_twi_instance, 0x77, &press_reg, 1, true);

but you have to call it like this

uint8_t address = 0x77;
nrf_drv_twi_tx(&p_twi_instance, address, &press_reg, 1, true);

You could try to type cast it, i.e.

nrf_drv_twi_tx(&p_twi_instance, (uint8_t)0x77, &press_reg, 1, true);

2) If you have provided it with a event handler,i.e. that the driver is event-driven and not blocking, then halting and starting the nRF51 could interfere with the event generation and handling.