/*
 * This program sets up ADC1 Sample Sequener 2 to convert
 * channel 8 and internal temperature.  The result of channel 8 is
 * written to the LEDs.
 * Analog channel 8 uses PORTE 5 pin and is connected to
 * a temperature sensor on Wytec EduBase board.
 */

#include "TM4C123GH6PM.h"

void delayMs(int n);
void delayUs(int n);

int main(void)
{
    int extTemp;
    int intTemp;

    SYSCTL->RCGCGPIO |= 0x10;       // enable clock to GPIOE
    SYSCTL->RCGCADC |= 2;           // enable clock to ADC1
    SYSCTL->RCGCGPIO |= 0x02;       // enable clock to GPIOB

    // initialize port pin PE5 for ADC1 input
    GPIOE->AFSEL |= 0x20;           // enable alternate function
    GPIOE->DEN &= ~0x20;            // disable digital function
    GPIOE->AMSEL |= 0x20;           // enable analog function

    // initialize ADC1 Sample Sequencer 2
    ADC1->ACTSS &= ~4;              // disable ADC1 Sequencer 2 during configuration
    ADC1->EMUX &= ~0x0F00;          // software trigger for sequencer 2
    ADC1->SSMUX2 &= ~0xFFFFFFFF;    // clear channel selects first
    ADC1->SSMUX2 |= 0x00000008;     // ch 8 for first sample
    ADC1->SSCTL2 |= 0x000000E0;     // finish sequence at 2nd sample with interal temperature and post RIS bit
    ADC1->ACTSS |= 4;               // enable ADC1 sequencer 2

    // enable PORTB 3-0 as output for LEDs
    GPIOB->DIR |= 0x0F;             // set PORTB 3-0 as output pins
    GPIOB->DEN |= 0x0F;             // set PORTB 3-0 as digital pins

    while(1)
    {
        ADC1->PSSI |= 4;                // start a conversion at sequencer 2
        while((ADC1->RIS & 4) == 0) ;   // wait for conversion sequence complete
        extTemp = ADC1->SSFIFO2;        // read conversion result of ch 8 from FIFO
        intTemp = ADC1->SSFIFO2;        // read conversion result of internal temp from FIFO
        ADC1->ISC = 4;                  // clear completion flag
        GPIOB->DATA = extTemp;          // write the external temperature to LEDs
        delayMs(100);
    }
}

// delay n milliseconds (16 MHz CPU clock)
void delayMs(int n)
{
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3180; j++)
            {}  // do nothing for 1 ms
}

// delay n microseconds (16 MHz CPU clock)
void delayUs(int n)
{
    int i, j;
    for(i = 0 ; i < n; i++)
        for(j = 0; j < 3; j++)
            {}  // do nothing for 1 us
}

// This function is called by the startup assembly
// code to perform system specific initialization tasks.
void SystemInit(void)
{
    // Grant coprocessor access
    // This is required since TM4C123G has
    // a floating point coprocessor
    SCB->CPACR |= 0x00f00000;
}