Ecriture du driver nécessaire au fonctionnement du STS21

lib/I2CDeviceLib/STS21.cpp

@@ -1 +1,172 @@
+#include "STS21.h"
 
+#define DEBUG
+
+double STS21::getTemperature(boolean noHold)
+{
+  uint8_t data[2] = {0,0};
+  double temperature(0.0);
+  uint16_t alignement(0);
+  
+  twi->beginTransmission(address);
+  if(noHold)
+    twi->write(NO_HOLD_MASTER);
+  else
+    twi->write(HOLD_MASTER);
+    
+  if(twi->endTransmission() != 0)
+    return temperature;//Error
+
+  if(noHold)
+  {
+    switch(_stsRes)
+    {
+      case RES_13:
+        delay(50);
+        break;
+      case RES_12:
+        delay(35);
+        break;
+      case RES_11:
+        delay(20);
+        break;
+      default:
+        delay(95);
+        break;
+    }
+  }
+
+  //On recupère les deux octets contenant la température
+  twi->requestFrom(address, (uint8_t)2);
+  if(twi->available() == 2)
+  {
+    data[0] = twi->read();
+    data[1] = twi->read();
+  }
+
+  alignement = data[0];
+  alignement <<= 8;
+  alignement += data[1] & 0xFC;
+  
+  temperature = -46.85 + 175.72 * ((double)alignement / 65536.0);
+
+  return temperature;
+}
+
+uint8_t STS21::readUserRegister()
+{
+  uint8_t returned(0);
+  
+  twi->beginTransmission(address);
+  twi->write(READ_USER_REG);
+  if(twi->endTransmission() != 0)
+    return 0;
+
+  twi->requestFrom(address, (uint8_t)1);
+
+  if(twi->available() == 1)
+  {
+    returned = twi->read();
+  }
+  
+  return returned;
+}
+
+boolean STS21::writeUserRegister(uint8_t value)
+{
+  twi->beginTransmission(address);
+  twi->write(WRITE_USER_REG);
+  twi->write(value);
+  
+  return twi->endTransmission() == 0;
+}
+
+boolean STS21::setResolution(STS_RES res)
+{
+  uint8_t userReg = readUserRegister();
+  boolean toBeReturned(false);
+  #ifdef DEBUG
+  Serial.printf("User Reg value before : %X\n",userReg);
+  #endif
+  
+  switch(res)
+  {
+    case RES_13:
+        userReg |= 0b10000000;
+        userReg &= 0b11111110;
+        break;
+      case RES_12:
+        userReg |= 0b00000001;
+        userReg &= 0b01111111;
+        break;
+      case RES_11:
+        userReg |= 0b10000001;
+        break;
+      default://Default is 14 bit resolution
+        userReg &= 0b01111110;
+        break;
+  }
+
+  if(writeUserRegister(userReg))
+  {
+    toBeReturned = true;
+    _stsRes = res;
+    #ifdef DEBUG
+    Serial.printf("Set resolution success\n");
+    #endif
+  }
+  
+  userReg = readUserRegister();
+  #ifdef DEBUG
+  Serial.printf("User Reg value after : %X\n",userReg);
+  #endif
+
+  return toBeReturned;
+}
+
+boolean STS21::enableOnChipHeater(boolean enabled)
+{
+  uint8_t userReg = readUserRegister();
+  boolean toBeReturned(false);
+  
+  #ifdef DEBUG
+  Serial.printf("User Reg value before : %X\n",userReg);
+  #endif
+
+  if(enabled)
+    userReg |= CHIP_HEATER;
+  else
+    userReg &= (~CHIP_HEATER);
+
+  if(writeUserRegister(userReg))
+  {
+    toBeReturned = true;
+    _onChipHeater = enabled;
+    #ifdef DEBUG
+    Serial.printf("Set chip heater success\n");
+    #endif
+  }
+  
+  userReg = readUserRegister();
+  #ifdef DEBUG
+  Serial.printf("User Reg value after : %X\n",userReg);
+  #endif
+
+  return toBeReturned;
+}
+
+boolean STS21::reset()
+{
+  boolean result;
+  twi->beginTransmission(address);
+  twi->write(SOFT_RST);
+  result = twi->endTransmission() == 0;
+  delay(30);
+  return result;
+}
+
+boolean STS21::lowBattery()
+{
+  uint8_t userReg = readUserRegister();
+  return userReg & END_OF_BAT;
+}

lib/I2CDeviceLib/STS21.h

@@ -1 +1,48 @@
+/*
+ * Anatole SCHRAMM-HENRY
+ * Tim THUREL
+ * Température groupe 3
+ * Date 14/02/2020 00:05
+ * 
+ * Classe permettant de piloter le STS21
+ * Capteur de température de la marque SENSIRION
+ * Précision : 0.2°C
+ * 
+ * Tout droit réservé
+ */
+#ifndef STS21_H
+#define STS21_H
 
+#include "I2CDevice.h"
+//Définition des commandes
+#define HOLD_MASTER 0xE3
+#define NO_HOLD_MASTER 0xF3
+#define WRITE_USER_REG 0xE6
+#define READ_USER_REG 0xE7
+#define SOFT_RST 0xFE
+
+//User register bits
+#define END_OF_BAT 0x40
+#define CHIP_HEATER 0x04
+
+class STS21 : public I2CDevice
+{
+  public:
+    enum STS_RES {RES_11 = 3, RES_12 = 1, RES_13 = 2, RES_14 = 0};
+    STS21(uint8_t addr = 0x4A):I2CDevice(addr), _onChipHeater(false), _stsRes(RES_14) {delay(20);}
+    ~STS21(){}
+    virtual boolean begin(){return I2CDevice::begin();};
+    double getTemperature(boolean noHold = true);//Degré celsius
+    boolean setResolution(STS_RES res);
+    boolean enableOnChipHeater(boolean enabled);
+    boolean reset();
+    boolean lowBattery();//Retourne vrai si le bit indiquant un niveau de batterie faible est present, faux sinon
+  protected:
+  private:
+    uint8_t readUserRegister();
+    boolean writeUserRegister(uint8_t value);
+    boolean _onChipHeater;
+    STS_RES _stsRes;
+};
+
+#endif //STS21_H