Tool/software:
Hi
I'ım using STM32 microcontroller and ADS124S08 with thermopile and NTC.
In particular, I can connect the thermopile and read the correct mV value. If I need to explain in detail, when I hold a flashlight to the thermopile, I read the same values from both the multimeter and the value displayed with mvValue. But when I disassemble the thermopile and read it when it is empty, it tends to drop down from 1249... mV. This is exactly what is shown in the video.
A second point is that when I connect the thermopile and cover it with my hand or cover it with something black, I get the same value of 1249... and this value remains constant. This is the situation in the photo.
Note: In both the video and the photo, the temperature sensor (NTC) is not connected.
My documents related to software and hardware are attached. Is there anything wrong? How can I overcome this problem?
/*
* Aut EArsanaci
* ADS124S08.c
*
*/
#include "ADS124S08.h"
#include "main.h"
#include <math.h>
extern SPI_HandleTypeDef hspi1;
extern struct ads124s08 adcValue;
extern struct irradiance irradiance;
// Initializes device for use in the ADS124S08
int8_t initDevice(void)
{
//Default register settings
// Reset Device
HAL_GPIO_WritePin(GPIOA, CS_Pin, RESET);
HAL_SPI_Transmit(&hspi1, (uint8_t *)RESET_OPCODE_MASK, 1, 100);
HAL_GPIO_WritePin(GPIOA, CS_Pin, SET);
//Write Ref Voltage
uint8_t write_refvolt[3] = {0};
write_refvolt[0] = 0x45;
write_refvolt[1] = 0x00;
write_refvolt[2] = 0x3A;
assertStart();
HAL_GPIO_WritePin(GPIOA, CS_Pin, RESET);
HAL_SPI_Transmit(&hspi1, write_refvolt, 3, 250);
HAL_GPIO_WritePin(GPIOA, CS_Pin, SET);
deassertStart();
return (1);
}
// Sets the GPIO hardware START pin HIGH
void assertStart()
{
HAL_GPIO_WritePin(GPIOA, START_Pin, SET);
}
// Sets the GPIO hardware START pin LOW
void deassertStart()
{
HAL_GPIO_WritePin(GPIOA, START_Pin, RESET);
}
// For start the device you need read data one time
void startDevice(void)
{
readDataThermopile(&adcValue);
}
void set_gain(uint8_t gain_data)
{
uint8_t write_gain[3] = {0};
write_gain[0] = 0x43;
write_gain[1] = 0x00;
write_gain[2] = gain_data;
assertStart();
HAL_GPIO_WritePin(GPIOA, CS_Pin, RESET);
HAL_SPI_Transmit(&hspi1, write_gain, 3, 250);
HAL_GPIO_WritePin(GPIOA, CS_Pin, SET);
deassertStart();
}
void change_inmux(uint8_t channel)
{
uint8_t write_mux[3] = {0};
write_mux[0] = 0x42;
write_mux[1] = 0x00;
write_mux[2] = channel;
assertStart();
HAL_GPIO_WritePin(GPIOA, CS_Pin, RESET);
HAL_SPI_Transmit(&hspi1, write_mux, 3, 250);
HAL_GPIO_WritePin(GPIOA, CS_Pin, SET);
deassertStart();
HAL_Delay(1);
}
void start_conversion()
{
//Start Conversion Mode
uint8_t start[1]= {0x08};
HAL_GPIO_WritePin(GPIOA, CS_Pin, RESET);
HAL_SPI_Transmit(&hspi1, start, 1, 250);
HAL_GPIO_WritePin(GPIOA, CS_Pin, SET);
HAL_Delay(1);
}
void readData(uint8_t *data)
{
uint8_t rdata[1]= {0x12};
assertStart();
HAL_GPIO_WritePin(GPIOA, CS_Pin, RESET);
HAL_SPI_Transmit(&hspi1, rdata, 1, 250);
HAL_SPI_Receive(&hspi1, data, 3, 250);
HAL_GPIO_WritePin(GPIOA, CS_Pin, SET);
deassertStart();
}
void readDataThermopile(struct ads124s08 *adcValue)
{
static double mvValue = 0;
set_gain(0x0A);
change_inmux(0x01);
start_conversion();
//Read Data Mux AIN0-AIN1
uint8_t rdata_data[3] = {0};
readData(rdata_data);
volatile int32_t value = (rdata_data[0] << 16) | (rdata_data[1] << 8) | rdata_data[2];
if(value > 0)
{
mvValue = ((value * 0.625 / 0x7FFFFF)*1000);
adcValue->mvValue = mvValue;
adcValue -> irr_adc = value;
}
}
void readDataNtc(struct ads124s08 *adcValue)
{
double ntcValue = 0;
double ntcOhm = 0;
static double temperature = 0;
uint8_t rdata_data[3] = {0};
set_gain(0x08);
change_inmux(0x23);
start_conversion();
readData(rdata_data);
volatile int32_t value = (rdata_data[0] << 16) | (rdata_data[1] << 8) | rdata_data[2];
if(value != 0)
{
ntcValue = value * 2.5/ 0x7FFFFF;
ntcOhm = (5e+7 * (2.5 - ntcValue)) / (25e+3 - (15e+3 * (2.5 - ntcValue)));
temperature = (1 /(1.123431435e-3 + (2.349138236e-4 * log(ntcOhm)) +
(0.8546607990e-7 * pow(log(ntcOhm),3))))- 273.15;
adcValue->temperature = temperature;
}
}
void calculateIrradiance(struct ads124s08 *adcValue, struct irradiance *irradiance)
{
irradiance->compIrradiance = adcValue->mvValue / adcValue->sensivity;
}
//void run_irradiance(struct irradiance *irradiance)
//{
// calculateIrradiance(&(irradiance->ads124s08), &irradiance);
//}
