Serial display of data using TWI

[Alanarf]

Hi all, 

i am using twi_scanner and twi_sensor as  templates to get data from CCS811 Air Quality sensor with PCA10040 and SDK 15.3.
But i cannot get the data printed in putty for example. 

I believe the issue could be on my set_mode() function, in which i try to set measurements every one second and instantiate the data register.
But putty is not showing anything.

Here is my set_mode function.

/**
 * @brief Function for setting constant mode 
 * Measurements every second
 */
void set_mode(void) 
{
    ret_code_t err_code;
	
	//Setting values of specific bits of the register byte
    /* Writing to CCS811_REG_CONF "1" set sensor in NORMAL mode. */
	
    uint8_t reg[2] = {CCS811_REG_MEAS_MODE, 1U };
    err_code = nrf_drv_twi_tx(&m_twi, device_id, reg, sizeof(reg), false);
    APP_ERROR_CHECK(err_code);
    while (m_xfer_done == false);
	
	NRF_LOG_INFO(" ************************************ ");
	NRF_LOG_INFO("Setting data pointer.");
	
	 /* Writing to pointer byte. */
	reg[0] = CCS811_REG_ALG_RESULT_DATA ;
    m_xfer_done = false;
    err_code = nrf_drv_twi_tx(&m_twi, device_id, reg, 1, false);
    APP_ERROR_CHECK(err_code);
    while (m_xfer_done == false);
}

Thanks,

[Jared]

Hi.

Have you made sure that you're using the recommended Putty settings as described in the TWI examples? Is the NRF LOG output displayed? Have you made sure that the application haven't asserted?

regards

Jared

[Alanarf]

Hi Jared, thanks for reply.

Yes, I am using the recommended settings.
NRF LOG outputs are visible on putty, but not the data.

TWI handle is called, but then nothing is shown on putty.

<Note about the sensor>
I need to set measurement mode on the chip, which i do in the set_mode() function by setting CCS811_REG_MEAS_MODE register to 1, this will set the sensor to measure values every second. 
<...>

Anyway, I removed the lines 17 to 25 from the function set_mode(), and created a new function called read_data_sensor(), which prints the strange value of 253 on putty.  You can see the  code for read_data_sensor()  bellow

static void read_sensor_data()
{
    ret_code_t err_code;
	m_xfer_done = false;
	
	//Setting sensor reading register 
    uint8_t reg = CCS811_REG_RAW_DATA;
	
    err_code = nrf_drv_twi_tx(&m_twi, DEVICE_ID, &reg, sizeof(reg), false);
    APP_ERROR_CHECK(err_code);
	if (err_code == NRF_SUCCESS){ //	If the procedure was successful.
			NRF_LOG_INFO("TX OK");
		} 

 
    err_code = nrf_drv_twi_rx(&m_twi, DEVICE_ID, &sample_data, sizeof(sample_data));
	APP_ERROR_CHECK(err_code);
	nrf_delay_ms(200);
	
			
        if (err_code == NRF_SUCCESS){ //	If the procedure was successful.
			NRF_LOG_INFO("Data received - reading data()");
	        
	    } 
		
}

And well i am stuck here, just getting 253 on putty, as if the register is ignored somehow =\
 

[Jared]

Where do you print "sample_data", and when is read_data_sensor() called? Have you checked that the NRF_DRV_TWI_EVT_DONE event has been generated before you read? If yes, then I suggest using the debugger to check what is stored in sample_data after a rx operation.