xmega-modbus-pt100/newcode/main.c

#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <stdlib.h>
#include <stddef.h>
#include "yaMBSiavr.h"

#define AVRG 512

#define SUPPLY_VOLTS 3.3
#define REF_OHMS 993.5

#define ADC_0V_COUNT 170
#define ADC_MAX_VOLT 1.95

volatile uint16_t adc_buffer[AVRG];
volatile float ch_values[9];

void init_clk(void)
{
    // ========= System Clock configuration =========
    // Set to external 16Mhz crystal, using the PLL at *2
    // set it to be a 12-16Mhz crystal with a slow start-up time.
    OSC.XOSCCTRL = OSC_FRQRANGE_2TO9_gc | OSC_XOSCSEL_XTAL_16KCLK_gc ;
    OSC.CTRL |= OSC_XOSCEN_bm ; // enable it
    while( (OSC.STATUS & OSC_XOSCRDY_bm) == 0 ){} // wait until it's stable

    // The external crystal is now running and stable.
    // (Note that it's not yet selected as the clock source)
    // Now configure the PLL to be eXternal oscillator * 2
    OSC.PLLCTRL = OSC_PLLSRC_XOSC_gc | 2;

    // now enable the PLL...
    OSC.CTRL |= OSC_PLLEN_bm ; // enable the PLL...
    while( (OSC.STATUS & OSC_PLLRDY_bm) == 0 ){} // wait until it's stable

    // And now, *finally*, we can switch from the internal 2Mhz clock to the PLL
    CCP = CCP_IOREG_gc;	// protected write follows   
    CLK.CTRL = CLK_SCLKSEL_PLL_gc;	// The System clock is now  PLL (16Mhz * 2)
    // ==============================================
}

void init_timer_100us(){
    TCC0.CTRLA |= TC_CLKSEL_DIV256_gc;
    TCC0.PER = 13; // ==> 9615Hz
    TCC0.INTCTRLA |= TC_OVFINTLVL_HI_gc;
}

void adc_init(void){
    ADCA.CTRLB = ADC_FREERUN_bm;
    ADCA.REFCTRL = ADC_REFSEL_VCC_gc;
    ADCA.PRESCALER = ADC_PRESCALER_DIV512_gc;

    uint8_t CalibrationByteL;
    uint8_t CalibrationByteH;
    NVM_CMD = NVM_CMD_READ_CALIB_ROW_gc;
    CalibrationByteL = pgm_read_byte(offsetof(NVM_PROD_SIGNATURES_t, ADCACAL0));
    CalibrationByteH = pgm_read_byte(offsetof(NVM_PROD_SIGNATURES_t, ADCACAL1));
    NVM_CMD = NVM_CMD_NO_OPERATION_gc;
    ADCA.CALL = CalibrationByteL;
    ADCA.CALH = CalibrationByteH;

    ADCA.CTRLA = ADC_ENABLE_bm;

    ADCA.CH0.CTRL = ADC_CH_INPUTMODE_SINGLEENDED_gc;
    ADCA.CH0.MUXCTRL = ADC_CH_MUXPOS_PIN0_gc;
}

uint16_t adc_read(void){
    ADCA.CH0.CTRL |= ADC_CH_START_bm;
    while(!(ADCA.CH0.INTFLAGS & ADC_CH_CHIF_bm));
    ADCA.CH0.INTFLAGS = ADC_CH_CHIF_bm;
    return ADCA.CH0.RES;
}

float avrg(uint16_t * values, uint16_t length){
    uint64_t res = 0;
    //ommit first and last sample
    for(uint16_t i=1; i < length-1; i++){
        res += values[i];
    }
    return (float)(res)/(length-2);
}

void dma_init(void){
    DMA.CTRL = DMA_ENABLE_bm;

    DMA.CH0.CTRLB = DMA_CH_TRNINTLVL_LO_gc;

    DMA.CH0.TRFCNT = AVRG * 2;
    DMA.CH0.CTRLA = DMA_CH_BURSTLEN_2BYTE_gc | DMA_CH_SINGLE_bm;
    DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_ADCA_CH0_gc;

    //repeat endless
    DMA.CH0.CTRLA |= DMA_CH_REPEAT_bm;
    DMA.CH0.REPCNT = 0;

    DMA.CH0.SRCADDR0 = ((uintptr_t)&ADCA.CH0.RES) & 0xFF;
    DMA.CH0.SRCADDR1 = (((uintptr_t)&ADCA.CH0.RES) >> 0x08) & 0xFF;
    DMA.CH0.SRCADDR2 = (((uintptr_t)&ADCA.CH0.RES) >> 0x0F) & 0xFF;

    DMA.CH0.DESTADDR0 = ((uintptr_t)adc_buffer) & 0xFF;
    DMA.CH0.DESTADDR1 = ((uintptr_t)adc_buffer >> 0x08) & 0xFF;
    DMA.CH0.DESTADDR2 = ((uintptr_t)adc_buffer >> 0x0F) & 0xFF;

    DMA.CH0.ADDRCTRL = DMA_CH_SRCRELOAD_BURST_gc | DMA_CH_DESTRELOAD_TRANSACTION_gc | DMA_CH_SRCDIR_INC_gc | DMA_CH_DESTDIR_INC_gc;

    DMA.CH0.CTRLA |= DMA_CH_ENABLE_bm;
}

void modbusGet(void) {
	if (modbusGetBusState() & (1<<ReceiveCompleted))
    {
        switch(rxbuffer[1]) {
            case fcReadHoldingRegisters: ;
                modbusExchangeRegisters(ch_values, 0, 18);
                break;
            default:
                modbusSendException(ecIllegalFunction);
                break;
        }
    }
}

int main(void){
    init_clk();
    PORTD.DIRSET = 1 << 5;
    PORTD.OUTTGL = 1 << 5;
    _delay_ms(500);
    PORTD.OUTTGL = 1 << 5;

    adc_init();
    dma_init();

    PORTCFG.MPCMASK = 0xFF;
    PORTC.PIN1CTRL = PORT_OPC_PULLUP_gc;

    init_timer_100us();

    PMIC.CTRL |= PMIC_LOLVLEN_bm | PMIC_MEDLVLEN_bm | PMIC_HILVLEN_bm; 
    sei();

    modbusSetAddress(1);
    modbusInit();

    for(;;){
        modbusGet();
    }
}

ISR(TCC0_OVF_vect){
    modbusTickTimer();
}

ISR(DMA_CH0_vect){
    static uint8_t pin = 0;

    DMA.INTFLAGS |= DMA_CH0TRNIF_bm; // clear flag
    DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_OFF_gc;
    ADCA.CTRLB = 0; // stop ADC

    uint8_t old_pin = pin;
    pin=(pin+1)%9;
    ADCA.CH0.MUXCTRL = pin << ADC_CH_MUXPOS_gp; // give MUX time to switch during averaging
    float temp = avrg(adc_buffer, AVRG);

    temp = temp - ADC_0V_COUNT;
    temp = (temp)/ (4096-ADC_0V_COUNT) * ADC_MAX_VOLT;
    temp = (temp * REF_OHMS)/(SUPPLY_VOLTS - temp);
    temp = (temp-100)/0.3927; //pt100 formula
    ch_values[old_pin] = temp;

    DMA.CH0.TRIGSRC = DMA_CH_TRIGSRC_ADCA_CH0_gc;
    ADCA.CTRLB = ADC_FREERUN_bm; // start ADC again
}