simple I2C question TC74

[americanhoney]

I have a TC74 temp sensor

https://www.microchip.com/wwwproducts/en/TC74

and want the temperature 

using code below I always get a greenlight / EVENTS ERROR

thank you in advance for any all help

int main(void)
{
short temperature = 0;

nrf_gpio_cfg_output(42); //output that needs to be off to power MEMs
nrf_gpio_cfg_output(46); //RED
nrf_gpio_cfg_output(47); //GREEN
nrf_gpio_pin_clear(42);
nrf_gpio_pin_set(46);//turns off LED
nrf_gpio_pin_set(47);//turns off LED

NRF_TWIM0->ENABLE=0;//disable nordic as master
NRF_TWIM0->PSEL.SCL=11;//P0.11
NRF_TWIM0->PSEL.SDA=13;//P0.13
NRF_TWIM0->FREQUENCY=0x01980000;//100kHz
NRF_TWIM0->ADDRESS=(0b11001000); // 1001 000--> x100 100 | x 1 fpr read 0 for write
NRF_TWIM0->RXD.PTR = temperature; //store 1 byte temperature in temperature variable
NRF_TWIM0->SHORTS = 0;
NRF_TWI0->INTENSET = 0x061C0202; // set interupts
NRF_TWIM0->ENABLE=6;//enable nordic as master
NRF_TWI0->TASKS_STARTRX = 1;
while (1)
{
if(NRF_TWI0->EVENTS_STOPPED) nrf_gpio_pin_clear(46);
if(NRF_TWI0->EVENTS_ERROR) nrf_gpio_pin_clear(47);//Always comes up with an error
}
}

[Kenneth]

You may find the reason for the EVENTS_ERROR here:
https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/twim.html?cp=3_1_0_32_7_4#register.ERRORSRC 

[americanhoney]

From what I can see (red light 'pin' 46) i am getting an overrun error.  I dont know how to fix or diagnose this though

int main(void)
{
    nrf_delay_ms(500);
    short temperature = 0;

    nrf_gpio_cfg_output(42); //output that needs to be off to power MEMs
    nrf_gpio_cfg_output(46); //RED
    nrf_gpio_cfg_output(47); //GREEN
    nrf_gpio_pin_clear(42);
    nrf_gpio_pin_set(46);//turns off LED
    nrf_gpio_pin_set(47);//turns off LED

    NRF_TWIM0->ENABLE=0;//disable nordic as master
    NRF_TWIM0->PSEL.SCL=11;//P0.11
    NRF_TWIM0->PSEL.SDA=13;//P0.13
    NRF_TWIM0->FREQUENCY=0x01980000;//100kHz
    NRF_TWIM0->ADDRESS=(0b11001000); // 1001 000--> x100 100 | x 1 fpr read 0 for write
    NRF_TWIM0->RXD.PTR = temperature; //store 1 byte temperature in temperature variable
    NRF_TWIM0->SHORTS = 0;
    NRF_TWI0->INTENSET = 0x061C0202; // set interupts
    NRF_TWIM0->ENABLE=6;//enable nordic as master
    NRF_TWI0->EVENTS_ERROR=0;
    NRF_TWI0->EVENTS_STOPPED=0;
    nrf_delay_ms(250);
    NRF_TWI0->TASKS_STARTRX = 1;
    while (1)
    {
//    if(NRF_TWI0->EVENTS_STOPPED) nrf_gpio_pin_clear(46);
  //  if(NRF_TWI0->EVENTS_ERROR) nrf_gpio_pin_clear(47);//Always comes up with an error
    if(NRF_TWIM0->ERRORSRC==1) nrf_gpio_pin_clear(46);//Always comes up with an error
    if(NRF_TWIM0->ERRORSRC==2) nrf_gpio_pin_clear(47);
    }
}

[americanhoney]

i got the error to go away using

NRF_TWI0->TASKS_STARTRX = 1;
while(NRF_TWI0->EVENTS_RXDREADY==0){}
NRF_TWI0->TASKS_STOP=1;
NRF_TWI0->EVENTS_RXDREADY=0;
temperature = NRF_TWI0->RXD;

but my temperature is zero. i must be receiving the temperature wrong.

[americanhoney]

can you provide example of how to properly get /access the byte read?

[awneil]

Have you looked at the TWI examples in the SDK?

[americanhoney]

yes

[americanhoney]

i shouldve been more specific, i meant an example of just how to get the read byte in my code. 

the manual says it is in pointer and to assign a location to pointer so i set NRF_TWIM0->RXD.PTR = temperature which i made a short since it is only 1 byte of data but temperature is always zero and my sensor is at room temperature so it should be a nonzero number.