CC2540 how to read the temperature sensor?

Thanks,

I'm getting close correct values now, I'll update this post when I get it exactly right (for future reference for other newbies like me).

This is my current getTemp:

float getTemp(void){ 
    unsigned int adcValue; 
    float outputVoltage; 
 
    TR0 |= 0x01; // TR0 must be modified prior to ATEST
    ATEST |= 0x01; // otherwise P0_0 and P0_1 forced with 0
    HalAdcSetReference ( HAL_ADC_REF_125V );
    adcValue = HalAdcRead( HAL_ADC_CHN_TEMP, HAL_ADC_RESOLUTION_12 );
    TR0 &= ~0x01;
    ATEST &= ~0x01;
    
    outputVoltage = adcValue * TEMP_CONST; 
 
    return ((outputVoltage - TEMP_OFFSET) / TEMP_COEFF); 
} 

The temperature sensor on the processor isn't calibrated and isn't consistent between devices. Also, the typical offset for the cc2541 is 1480 (from datasheet), not 750. The sample code you're using is for a different processor and I think the constants and coefficients are different.

I've found that the following gives me something close to 1 degree C per count.  But take note, this hasn't been fully tested.

You will have to add/subtract an offset to the result , different for different devices.  See what temperature the device reports, note what the actual temperature is, the difference between the two is your offset.  Note that the scaling factor (or lack of one) may produce errors, but it's close enough for my purposes.

int8 temperature_2541( void )  //  retrieve temperature.
{
    
    TR0 = 0x01;  //  Connect temperature sensor to ADC.
    ATEST |= 0x01;

    ADCCON3 = 0x3e;  //  Start the ADC conversion using the temperature sensor input.
    
    int timeout = 1000;
    
    while( !( ADCCON1 & 0x80 ) && --timeout );  // Poll the conversion ready flag.
    
    if( timeout == 0 )
        return 0xFF;
    else
    {
        //  Put the upper and lower bytes together.
        uint16 result = ( ( uint16 )ADCH << 8 );
        result |= ADCL;
        
        result >>= 4;  //  12 bit ADC, shift into position
        
        result -= 1480;  //  Offset at 25 degrees C, from the datasheet.  We ultimately only have 8 bits for temperature, so we need to get rid of the offset here.
        
        //  If we shift down 2 bits, we get something close to 1 count per degree.        
        result >>= 2;
        
        return ( int8) result;
    }
}

Hi everyone, 

I have two voltage output sensors (external  temperature and humidity). I have connected them to the CC2540 module. I attempting to read the output and convert it to temperature and humidity readings. 

1. My question is Dan Nelson can i use the code upwards or it is for the internal sensor on the module. 

2. If not is there formula to convert the ADC readings into humidity or temperature. 

3. Can i do read two adc ADC0 and ADC1 at the same time or i have to give like a delay. In giving a delay is timers the best way since they are not that accurate. 

Any input will be very much appreciated. My deadline is coming up really fast.

Thank you.

Joseph

I am doing project with CC2540 development kit. I have a central device and a peripheral device. i want to program for temperature sensor. How did you create this code and on what basics?