TWI no data from Sensor

[Inspectron]

I have a temperature/humidity sensor from Sensirion. The Type is SHT21x. The sensor has I2C so it should be able to tranfer the data from the sensor to the Nordic chip over I2C. I`m working with the nRF51DK. The sensor works fine. I wrote my own I2C protocol with bit banging and both measurements did what they should. Now I want to use the soft device, because later I would like to send the data to a mobile device. So I tried to get it work with the twi_hw_master example.

SoftDevice 8.0.0 is flashed on the chip.

The measurement for the humidity works fine! But when I try to read the temperature I wont get data from the sensor. But I do get the ACK when I send the read command for the temperature.

I have a case open on nordic support but for days the problem wont get fixed. Maybe somebody worked with the sensor from Sensiron and had the same problem?

Below my code:

static void timer_timeout_handler()
{
 hum_temp = !hum_temp;
 if(hum_temp == true)
 {
	nrf_gpio_pin_toggle(24);
	twi_master_transfer(0x80, &hm_hum, 1,0);
	twi_master_transfer(0x81, hum_data,3,1);
	nrf_gpio_port_write(NRF_GPIO_PORT_SELECT_PORT1, *hum_data);
 }
 else
 {
	nrf_gpio_pin_toggle(23);
	twi_master_transfer(0x80, &hm_temp, 1,0);
	twi_master_transfer(0x81, temp_data,3,1);
	nrf_gpio_port_write(NRF_GPIO_PORT_SELECT_PORT1, *temp_data);
 }
}

Every 2 seconds I will jump in the timer_timeout_ handler() routine.

Here the read function:

static bool twi_master_read(uint8_t *data, uint8_t data_length, bool issue_stop_condition)
{
    uint32_t timeout = MAX_TIMEOUT_LOOPS;   /* max loops to wait for RXDREADY event*/

if (data_length == 0)
{
    /* Return false for requesting data of size 0 */
    NRF_TWI1->SHORTS = 0; //short are not enabled yet, may not be necessary
    return false;
}
else if (data_length == 1)
{
    NRF_TWI1->SHORTS = TWI_SHORTS_BB_STOP_Enabled << TWI_SHORTS_BB_STOP_Pos;
}
else
{
    NRF_TWI1->SHORTS = TWI_SHORTS_BB_SUSPEND_Enabled << TWI_SHORTS_BB_SUSPEND_Pos;
}

NRF_TWI1->EVENTS_RXDREADY = 0;
NRF_TWI1->TASKS_STARTRX   = 1;

/** @snippet [TWI HW master read] */
while (true)
{
    while(NRF_TWI1->EVENTS_RXDREADY == 0 && NRF_TWI1->EVENTS_ERROR == 0 && (--timeout))
    {
        // Do nothing.
    }
    NRF_TWI1->EVENTS_RXDREADY = 0;

    if (timeout == 0 || NRF_TWI1->EVENTS_ERROR != 0)
    {
      // Recover the peripheral as indicated by PAN 56: "TWI: TWI module lock-up." found at
      // Product Anomaly Notification document found at
      // www.nordicsemi.com/.../
      NRF_TWI1->EVENTS_ERROR = 0;
      NRF_TWI1->ENABLE       = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
      NRF_TWI1->POWER        = 0;
      nrf_delay_us(5);
      NRF_TWI1->POWER        = 1;
      NRF_TWI1->ENABLE       = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;

      (void)twi_master_init();

      NRF_TWI1->SHORTS = 0;
      return false;
    }

    *data++ = NRF_TWI1->RXD;

    if (--data_length == 1)
    {
        NRF_TWI1->SHORTS = TWI_SHORTS_BB_STOP_Enabled << TWI_SHORTS_BB_STOP_Pos;
    }

    if (data_length == 0)
    {
        break;
    }

    // Recover the peripheral as indicated by PAN 56: "TWI: TWI module lock-up." found at
    // Product Anomaly Notification document found at
    // www.nordicsemi.com/.../
    nrf_delay_us(20);
    NRF_TWI1->TASKS_RESUME = 1;
}
/** @snippet [TWI HW master read] */

/* Wait until stop sequence is sent */
while(NRF_TWI1->EVENTS_STOPPED == 0)
{
    // Do nothing.
}
NRF_TWI1->EVENTS_STOPPED = 0;

NRF_TWI1->SHORTS = 0;
	
return true;
}

I need to know how to fix this problem.

[Alex]

Another idea, with SD you need to use sd_twi_hw_master.c

[Alex]

But I would also check with oscilloscope how Hold works and what exactly data on the bus

[Inspectron]

The default resolution is 12bit humidity and 14bit temperature. I didnt change this. I have the humidity reading on my osciloscope screen. And there I see that after the read +ACK I get Data from the sensor. I`m not sure if the data are right, because they arent a value. I see the data on 8 additonal LEDs on Port 1

[Inspectron]

The problem is, that after the clock is released, the nRF51Dk doesnt clocks. The only diference between hum and temp measuring is the time atfer the read command. After the read command for hummidty it takes 22ms until the clock will be released. For the temperature it takes 67ms. Could this be a problem for the sd_twi_hw_master.c ?

[Alex]

Does twi_master_read return true or false? May be it times out?