Lesson 18: Analog to Digital Converter (ADC)

Keil C Sample Firmware Code

Please follow this article to add ezTiva LIB into your project.

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <stdint.h>
 
#include "TM4C1294NCPDT.h"
#include "ez1294.h"

void Setup_ADC_SS3_CH9(void);
void Setup_UART0(void);
void UART_PrintString(char * s);
void DelayMs(int s);

char str[100];
uint32_t result;

int main(void)
{
    Setup_1294_80MHz(); // Setup SystemClock to 80MHz
    Setup_ADC_SS3_CH9();
    Setup_UART0();

    // Enable GPIOA[0][1] for UART, PE[4] for ADC
    // Config for GPIO
    // 1. Enable Clock on GPIOA, GPIOE (SYSCTL_RCGCGPIO)

    // allow time for clock to stabilize (SYSCTL_PRGPIO)
    
    // 2. Unlock for TM4C123:PORTC[3:0],PORTD[7],and PORTF[0]; TM4C1294:GPIOD[7]
    // 3. Config AMSEL for PortE[4] to enable analog

    // 4. Config PCTL to select GPIO

    // 5. Enable AFSEL bits to 1 for PortA[1:0] and PortE[4]

    // 6. Set DIR to 0 for input, 1 for output

    // 7. Set PUE bits to 1 to enable internal pull-up
    // 8. Set DEN bits to 1 to enable digital data pins, write 0 to disable digital function

    sprintf(str,"EE-3450: ADC Test \n\r");
    UART_PrintString(str);
    while(1){
        // Initiate SS3
        ADC0->PSSI = 0x08;
        // Waiting for conversion done
        while ((ADC0->RIS & 0x08) != 0x08) {};
        result = ADC0->SSFIFO3 & 0xFFF;     // Read 12-bit result
        ADC0->ISC = 0x08;   // Acknowledge completion
        sprintf(str,"ADC result = %d \n\r", result);
        UART_PrintString(str);
        DelayMs(100);
    }
}

void Setup_ADC_SS3_CH9(void)
{
    // 1. Enable the ADC clock (SYSCTL_RGCGADC)
    SYSCTL->RCGCADC |= 0x01;
    while ((SYSCTL->PRADC & 0x01) != 0x01) {};
    // 2. Configure max sampling rate (ADCn_PC_R)
    ADC0->PC = 0x01;  // 0x01: 12Ksps
    // 3. Configure Sequencer # priority
    ADC0->SSPRI = 0x0123;
    // 4. Disable Sample Sequencer
    ADC0->ACTSS &= ~(1<<3);
    // 5. Configure triggle mode
    ADC0->EMUX &= ~(0xF000);  // 0x00: Software triggle
    // 6. COnfigure ADC chanel
    ADC0->SSMUX3 = (ADC0->SSMUX3 & 0xFFFFFFF0) + 9; // Use chanel 9
    // 7. Set flag on sample capture
    ADC0->SSCTL3 = 0x0006;    //no TS0 D0, yes IE0 END0
    // 8. COnfigure interrupt
    ADC0->IM &= ~0x0008;      // Disable SS3 interrupt
    // 9. Enable Sample Sequencer
    ADC0->ACTSS |= 0x0008;
}

void Setup_UART0(void)
{
// Config BuadRate as 115200bps
#define UARTIBRD ??
#define UARTFBRD ??
 
    // 1. Enable clock to UART Module 0 (SYSCTL_RCGCUART)
    SYSCTL->RCGCUART |= 0x01;
        // allow time for clock to stabilize
    while((SYSCTL->PRUART & 0x01) != 0x01){};
    // 2. Disable UART by clearing UARTEN in UARTCTL register
    UART0->CTL &= ~(0x00000001);
    // 3. Write BRD to UARTIBRD and UARTFBRD register
    UART0->IBRD = UARTIBRD;
    UART0->FBRD = UARTFBRD;
    // 4. Write UART Line control (UARTLCRH register)
    //    8bit, No parity, 1-stop bit, no FIFO = 0x00000060
    UART0->LCRH = 0x60;
    // 5. Configure the UART clock source (UARTCC register)
    UART0->CC = 0x00;   // Clock Source from System Clock
    // 6. Enable UART by clearing UARTEN in UARTCTL register
    UART0->CTL = 0x301; // Enable UART0, TXE, RXE
} 
void UART_PrintString(char * s)
{
    char ch;
    
    ch = *s;
    while( ch != NULL  ){
        while( (UART0->FR & 0x80) != 0x80) {};
        UART0->DR = ch;
        s++;
        ch = *s;     
    }
}
void DelayMs(int s)
{
    volatile int i, j;
    for (i = 0; i < s; i++)
        for (j = 0; j < 3180; j++)
            {};
}