stm32samples/F0-nolib/Chiller/adc.c

/*
 * This file is part of the Chiller project.
 * Copyright 2018 Edward V. Emelianov <edward.emelianoff@gmail.com>.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include "adc.h"

/**
 * @brief ADC_array - array for ADC channels with median filtering:
 * 0..3 - external NTC
 * 4 - internal Tsens
 * 5 - Vref
 */
uint16_t ADC_array[NUMBER_OF_ADC_CHANNELS*9];

/**
 * @brief getADCval - calculate median value for `nch` channel
 * @param nch - number of channel
 * @return
 */
uint16_t getADCval(int nch){
    int i, addr = nch;
    register uint16_t temp;
#define PIX_SORT(a,b) { if ((a)>(b)) PIX_SWAP((a),(b)); }
#define PIX_SWAP(a,b) { temp=(a);(a)=(b);(b)=temp; }
    uint16_t p[9];
    for(i = 0; i < 9; ++i, addr += NUMBER_OF_ADC_CHANNELS) // first we should prepare array for optmed
        p[i] = ADC_array[addr];
    PIX_SORT(p[1], p[2]) ; PIX_SORT(p[4], p[5]) ; PIX_SORT(p[7], p[8]) ;
    PIX_SORT(p[0], p[1]) ; PIX_SORT(p[3], p[4]) ; PIX_SORT(p[6], p[7]) ;
    PIX_SORT(p[1], p[2]) ; PIX_SORT(p[4], p[5]) ; PIX_SORT(p[7], p[8]) ;
    PIX_SORT(p[0], p[3]) ; PIX_SORT(p[5], p[8]) ; PIX_SORT(p[4], p[7]) ;
    PIX_SORT(p[3], p[6]) ; PIX_SORT(p[1], p[4]) ; PIX_SORT(p[2], p[5]) ;
    PIX_SORT(p[4], p[7]) ; PIX_SORT(p[4], p[2]) ; PIX_SORT(p[6], p[4]) ;
    PIX_SORT(p[4], p[2]) ;
    return p[4];
#undef PIX_SORT
#undef PIX_SWAP
}

// return MCU temperature (degrees of celsius * 10)
int32_t getMCUtemp(){
    getVdd();
    // make correction on Vdd value
//    int32_t temperature = (int32_t)ADC_array[4] * VddValue / 330;
    int32_t ADval = getADCval(4);
    int32_t temperature = (int32_t) *TEMP30_CAL_ADDR - ADval;
    temperature *= (int32_t)(1100 - 300);
    temperature /= (int32_t)(*TEMP30_CAL_ADDR - *TEMP110_CAL_ADDR);
    temperature += 300;
    return(temperature);
}

// return Vdd * 100 (V)
uint32_t getVdd(){
    uint32_t vdd = ((uint32_t) *VREFINT_CAL_ADDR) * (uint32_t)330; // 3.3V
    vdd /= getADCval(5);
    return vdd;
}

/**
 * @brief getNTC - return temperature of NTC (*10 degrC)
 * @param nch - NTC channel number (0..3)
 * @return
 */
int16_t getNTC(int nch){
#define NKNOTS  (9)
    const int16_t ADU[NKNOTS] = {427,   468,  514,  623,  754, 910, 1087, 1295, 1538};
    const int16_t T[NKNOTS]   = {-200, -180, -159, -116,  -72, -26,   23,   75,  132};
    /*
     * coefficients: 0.050477   0.045107   0.039150   0.033639   0.029785   0.027017   0.024996   0.023522   0.022514
     * use
     * [N D] = rat(K*10); printf("%d, ", N); printf("%d, ", D);
     */
    const int16_t N[NKNOTS] = {1377, 295, 258, 110, 291, 77, 1657, 191, 120};
    const int16_t D[NKNOTS] = {2728, 654, 659, 327, 977, 285, 6629, 812, 533};

    if(nch < 0 || nch > 3) return -30000;
    uint16_t val = getADCval(nch);
    // find interval
    int idx = (NKNOTS)/2, left = 0, right = NKNOTS-1; // left, right, middle
    while(idx > left && idx < right){
        int16_t midval = ADU[idx];
        if(val < midval){
            if(idx == 0) break;
            if(val > ADU[idx-1]){ // found
                --idx;
                break;
            }
            right = idx - 1;
            idx = (left + right)/2;
        }else{
            if(val < ADU[idx+1]) break;  // found
            left = idx + 1;
            idx = (left + right)/2;
        }
    }
    if(idx < 0) idx = 0;
    else if(idx > NKNOTS-1) idx = NKNOTS - 1;
    // T = Y0(idx) + K(idx) * (ADU - X0(idx));
    int16_t valT = T[idx] + (N[idx]*(val - ADU[idx]))/D[idx];
#undef NKNOTS
    return valT;
}