/* ADC - Potentiometer, Photo Sensor, Temperature sensor to LEDs
 *
 * This program is an example of performing a sequence of
 * multiple channel conversion. The sequence starts at result
 * memory register 4 and ends at result memory register 6.
 * The assignments of input channels are as follows:
 * MEM4 - A8  - P4.5 - light sensor
 * MEM5 - A6  - P4.7 - potentiometer
 * MEM6 - A10 - P4.3 - temperature sensor
 *
 * Once the conversions are started by software, the program
 * polls for the completion flag of MEM6, the last channel.
 * When the last channel conversion is completed, the conversion
 * results are read and displayed on the LEDs.
 * The pushbutton switches are used to select the channel for display:
 * SW4 SW5
 *  0   0  - light sensor
 *  1   0  - potentiometer
 *  0   1  - temperature sensor
 *  1   1  - no output
 *
 * Built and tested with MSP432P401R Rev. C, Keil MDK-ARM v5.24a and MSP432P4xx_DFP v3.1.0
 */

#include "msp.h"

void display(int data);

int main(void) {
    int data[4] = {0};
    int shifts[4] = {8, 8, 0, 0};

    P2->DIR |= 0x30;        /* P2.5, P2.4 set as output for LEDs */
    P3->DIR |= 0x0C;        /* P3.3, P3.2 set as output for LEDs */
    P6->DIR &= ~2;          /* P6.1 set as input */
    P4->DIR &= ~0x15;       /* P4.4, P4.2, P4.0 input */

    ADC14->CTL0 =  0x00000010;      /* power on and disabled during configuration */
    ADC14->CTL0 |= 0x040A0380;      /* S/H pulse mode, sysclk, 32 sample clocks, multiple channel conversion sequence, software trigger */
    ADC14->CTL1 =  0x00040020;      /* 12-bit resolution, starting from result memory 4 */

    ADC14->MCTL[4] |= 8;            /* select A8 input; Vref=AVCC */
    P4->SEL1 |= 0x20;               /* Configure P4.5 for A8 */
    P4->SEL0 |= 0x20;

    ADC14->MCTL[5] |= 6;            /* select A6 input; Vref=AVCC */
    P4->SEL1 |= 0x80;               /* Configure P4.7 for A6 */
    P4->SEL0 |= 0x80;

    ADC14->MCTL[6] |= 10 | 0x80;    /* select A10 input; Vref=AVCC; end of sequence */
    P4->SEL1 |= 0x08;               /* Configure P4.3 for A10 */
    P4->SEL0 |= 0x08;

    ADC14->CTL0 |=  0x00000002;     /* enable the converter */

    while (1) {
        int channel = 0;
        
        ADC14->CTL0 |= 1;           /* start a conversion sequence */
        while (!(ADC14->IFGR0 & 0x00000040)); /* wait till last channel in the sequence complete */
        data[0] = ADC14->MEM[4];    /* read the conversion results */
        data[1] = ADC14->MEM[5];
        data[2] = ADC14->MEM[6];

        if (P4->IN & 1 << 0)
            channel |= 1;
        
        if (P6->IN & 1 << 1)
            channel |= 2;
    
        display(data[channel] >> shifts[channel]);
    }
}

void display(int data) {		
    if (data & 8)              /* bit 3 -> LED3 */
        P2->OUT |= 0x10;
    else
        P2->OUT &= ~0x10;
    
    if (data & 4)              /* bit 2 -> LED2 */
        P2->OUT |= 0x20;
    else
        P2->OUT &= ~0x20;
    
    if (data & 2)              /* bit 1 -> LED1 */
        P3->OUT |= 8;
    else
        P3->OUT &= ~8;
    
    if (data & 1)              /* bit 0 -> LED0 */
        P3->OUT |= 4;
    else
        P3->OUT &= ~4;        
}