CCS/TM4C1294NCPDT: Read Temperature Data via ADC0SS3 using ADC interrupt

Tool/software: Code Composer Studio

I am working on a project in which I'm attempting to read from an external Temperature Sensor (TMP36) using ADC module 0 Sample Sequencer 3.

I am connecting the sensor to PD2 for AIN13

The first sample is processor triggered and then I set it to be continuously sampled in the interrupt handler.

I walked through the data sheet multiple times and am not sure what I am doing wrong in my code. It seems that in my code I never enter my interrupt handler and therefore never get data from the sensor but I'm not sure how to fix that. I used a test value to see if I ever entered the interrupt handler and the value never updated.

At this point I am not even sure where the issue may lie, I've been debugging for over a week and am not really sure what to do next.

// this file assumes the temperature sensor
// uses analog channel 13 to do the AD Conversion
// the voltage reflecting the measured temperature
// can be calculated by reading the register ADC0_SSFIFO3_R
// where only the lowest 12 bits are accesible
// Since AN#13 is multiplexed with GPIO Pin D2
// so relevant GPIO Port D configuration is needed

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

// providing clock to GPIO module
#define SYSCTL_RCGCGPIO_R       (*((volatile unsigned long *)0x400FE608))

// providing clock to ADC module
#define SYSCTL_RCGCADC_R        (*((volatile unsigned long *)0x400FE638))

// ADC0 and SS3
#define ADC0_ACTSS_R            (*((volatile unsigned long *)0x40038000))   // enable ss3
#define ADC0_IM_R               (*((volatile unsigned long *)0x40038008))   // interrupt mask
#define ADC0_ISC_R              (*((volatile unsigned long *)0x4003800C))   // interrupt clear
#define ADC0_EMUX_R             (*((volatile unsigned long *)0x40038014))
#define ADC0_PSSI_R             (*((volatile unsigned long *)0x40038028))
#define ADC0_SAC_R              (*((volatile unsigned long *)0x40038030))   // oversampling
#define ADC0_SSEMUX3_R          (*((volatile unsigned long *)0x400380B8))
#define ADC0_SSMUX3_R           (*((volatile unsigned long *)0x400380A0))
#define ADC0_SSCTL3_R           (*((volatile unsigned long *)0x400380A4))
#define ADC0_SSFIFO3_R          (*((volatile unsigned long *)0x400380A8))
#define ADC0_PC_R               (*((volatile unsigned long *)0x40038FC4))

// GPIO port D
#define GPIO_PORTD_AHB_DIR_R    (*((volatile unsigned long *)0x4005B400))
#define GPIO_PORTD_AHB_DEN_R    (*((volatile unsigned long *)0x4005B51C))
#define GPIO_PORTD_AHB_AMSEL_R  (*((volatile unsigned long *)0x4005B528))
#define GPIO_PORTD_AHB_AFSEL_R  (*((volatile unsigned long *)0x4005B420))
//#define GPIO_PORTD_AHB_DATA_R   (*((volatile unsigned long *)0x4005B3FC))

// NVIC interrupt module
#define NVIC_EN0_R              (*((volatile unsigned long *)0xE000E100))
uint32_t TempData;
//uint32_t Test = 2;


// This function generates the delay
void Delay ( volatile unsigned int delay ){
    volatile unsigned int i, j;

    for (i = 0; i < delay ; i++) {
        // introduces a delay of about 10 us at 16 MHz
        for (j = 0; j < 12; j ++) ;
  }
}


// ADC0 interrupt service routine for sequencer 3
void ADC0SS3_Handler (void) {
//    Test++;
    ADC0_EMUX_R |= 0xF000;
    ADC0_ISC_R |= 0x08;
    TempData = ADC0_SSFIFO3_R; //& 0x0FFF;

}



// main function
int main ( void ){

    volatile float Temp;
//  1. Enable the clock for ADC0
    SYSCTL_RCGCADC_R |= 0x01;
//  2. Enable the clock to Port D
    SYSCTL_RCGCGPIO_R |= 0x08;

    // configuration of port D pin2
    GPIO_PORTD_AHB_AFSEL_R |= 0x04; // functions as analog let AIN13 work
    GPIO_PORTD_AHB_DEN_R &= 0x00;   // disable digital enable analog
    GPIO_PORTD_AHB_AMSEL_R |= 0x04; // enable analog
    GPIO_PORTD_AHB_DIR_R &= 0x00;   // 0 for input

    // Initiate sequencer 3
    ADC0_PSSI_R |= 0x08;

    // and introduce a delay by call Delay function
     Delay (3);

    // Select AIN13 ( PD2 ) as the analog input
    // 1st sample is end of sequence and source of interrupt
    ADC0_PC_R |= 0x03;          // quarter convertion rate; 48*Tadc periods pause
    ADC0_SAC_R  |= 0x04;        // 16x oversampling and then averaged

    // Unmask ADC0 sequence 3 interrupt
    ADC0_IM_R |= 0xF7;      // step 6
    // Clear the interrupt for ADC0 sequencer 3
    ADC0_ISC_R |= 0x08;


    // Enable ADC0 module for sequencer 3
    ADC0_ACTSS_R &= 0x00; // step 1 disabling sample sequencer 3
    ADC0_EMUX_R &= 0x0000;
    ADC0_SSEMUX3_R = 0x0;
    ADC0_SSMUX3_R |= 0x0D;  // step 4 select AIN13
    ADC0_SSCTL3_R |= 0x06;  // step 5
    ADC0_IM_R |= 0x08;      // step 6
    ADC0_ACTSS_R |= 0x08;   // step 7 enabling sample sequencer 3
    ADC0_ISC_R |= 0x08;


    // Enable ADC0 sequencer 3 interrupt in NVIC interrupt number is 17
    NVIC_EN0_R |= 0x020000;

    // wait certain time for ADC module do the conversion
    Delay(100);

    while (1) {
    }
}