source: azure_iot_hub_f767zi/trunk/app_iothub_client/pinkit/temperature.c@ 457

// https://github.com/ms-iotkithol-jp/IoTKitHoLV3/blob/master/PinKitIoTHubApp/PinKitIoTHubApp/PinKit/Temperature.cs

#include <math.h>
#include <kernel.h>
#include <t_syslog.h>
#include <target_syssvc.h>
#include "pinkit.h"
#include "kernel_cfg.h"

ADC_Handle_t *aiTemperature;

// Adjust VR1 - Default 5000Ω
double VR1;

// B constant - Default 3435Ω
double Bc;

volatile uint16_t TemperatureValue;

/*
 *  ADC転送終了コールバック関数
 */
static void HAL_ADC_ConvCpltCallback2(ADC_Handle_t* hadc)
{
        TemperatureValue = adc_getvalue(aiTemperature);
        adc_end_int(hadc);
}

bool Temperature_Init()
{
        ADC_Init_t     aInit;
        ADC_ChannelConf_t sConfig;
        uint32_t event = 0;
        int i;
        Arduino_PortControlBlock *pcb;

        VR1 = 5000.0;
        Bc = 3435.0;

        /*
         *  ADC5初期化
         */
        aInit.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
        aInit.Resolution = ADC_RESOLUTION_12B;
        aInit.ScanConvMode = ADC_SCANMODE_DISABLE;
        aInit.ContinuousConvMode = ADC_CONTINUOUS_ENABLE;
        aInit.DiscontinuousConvMode = ADC_DISCONTINUOUS_DISABLE;
        aInit.NumDiscConversion = 0;
        aInit.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
        aInit.ExternalTrigConv = ADC_EXTERNALTRIGCONV_T1_CC1;
        aInit.DataAlign = ADC_DATAALIGN_RIGHT;
        aInit.NumConversion = 1;
        aInit.DMAContinuousRequests = ADC_DMACONTINUOUS_DISABLE;
        aInit.EOCSelection = ADC_EOC_SEQ_DISABLE;

        if((aiTemperature = adc_init(ADC3_PORTID, &aInit)) == NULL){
                /* Initialization Error */
                syslog_0(LOG_ERROR, "## adc_init ERROR ##");
                return false;
        }
        aiTemperature->xfercallback = HAL_ADC_ConvCpltCallback2;

        /*
         *  ADCチャネル設定
         */
        pcb = getGpioTable(ANALOG_PIN, 5);
        sConfig.Channel = ADC_CHANNEL_8;
        sConfig.Rank = 1;
        sConfig.SamplingTime = ADC_SAMPLETIME_480CYCLES;
        sConfig.GpioBase = pcb->giobase;
        sConfig.GpioPin  = pcb->giopin;
        if(adc_setupchannel(aiTemperature, &sConfig) != E_OK){
                /* Channel Configuration Error */
                syslog_0(LOG_ERROR, "## adc_setupchannel ERROR ##");
                return false;
        }

        /*
         *  ADC DMAスタート
         */
        if(adc_start_int(aiTemperature) != E_OK){
                /* Start Conversation Error */
                syslog_0(LOG_ERROR, "## adc_start_int ERROR ##");
                return false;
        }

        return true;
}

bool Temperature_Start()
{
        if (aiTemperature->status >= ADC_STATUS_EOC)
                return false;

        /*
         *  ADC DMAスタート
         */
        if(adc_start_int(aiTemperature) != E_OK){
                /* Start Conversation Error */
                syslog_0(LOG_NOTICE, "## adc_start_int ERROR ##");
                return false;
        }

        return true;
}

double Temperature_TakeMeasurement()
{
        if (aiTemperature == NULL)
                return -273.15;

        int raw = TemperatureValue << (16 - 12);

        double tk = 273.0;
        double t25 = tk + 25.0;
        double r25 = 10000.0;
        double t = 1.0 / (log(VR1 * raw / (65536 - raw) / r25) / Bc + 1.0 / t25) - tk;
        return t;
}