Init

src/sensor/dev/sgp40.cpp

@@ -0,0 +1,180 @@
+#include "sgp40.h"
+
+
+/****************************************************************/
+bool SGP40::Initialize(){
+   bool success(true);
+
+   success &= ReadChipID();
+
+   VocAlgorithm_init(&vocAlgorithmParameters);
+
+   if(success) success = WriteSettings();
+   
+   m_initialized = success;
+   return m_initialized;
+}
+
+
+/****************************************************************/
+bool SGP40::ReadChipID(){
+   uint8_t id = 0;
+
+   //ReadRegister(ID_ADDR, &id, 1);
+
+   switch(id){
+      default:
+         m_chip_model = ChipModel_UNKNOWN;
+         return false;
+   }
+
+   return true;
+}
+
+
+/****************************************************************/
+bool SGP40::WriteSettings(){
+    uint8_t data[3];
+    uint8_t ord(0);
+
+    i2c->beginTransmission(SGP40_ADDRESS);
+    i2c->write(highByte(REG_MEASURE_TEST));
+    i2c->write(lowByte(REG_MEASURE_TEST));
+    i2c->endTransmission();
+
+    delay(320);
+
+    i2c->requestFrom(static_cast<uint8_t>(SGP40_ADDRESS), uint8_t(3));
+
+    while(i2c->available()){
+        data[ord++] = i2c->read();
+    }
+    if(ord != 3) return false;
+    uint16_t results = (data[0] << 8) | data[1];
+
+    return (results == test_pass);
+}
+
+
+/****************************************************************/
+bool SGP40::begin(){
+   bool success = Initialize();
+   success &= m_initialized;
+   return success;
+}
+
+/****************************************************************/
+bool SGP40::reset(){
+   WriteRegister(RESET_ADDR, 0x02);
+   delay(10); //max. startup time according to datasheet
+   return(begin());
+}
+
+/****************************************************************/
+bool SGP40::ReadData(uint8_t data[SENSOR_DATA_LENGTH], float RH, float T){
+    bool success;
+    uint8_t ord(0);
+
+    RH = (RH>100?100: (RH<0?0:RH));
+    T =  (T>130?130: (T<-45?-45:T));
+
+    uint16_t RH_ticks = (uint16_t)(RH * 65535 / 100); // Convert RH from %RH to ticks
+    uint16_t T_ticks = (uint16_t)((T + 45) * 65535 / 175); // Convert T from DegC to ticks
+    
+    i2c->beginTransmission(SGP40_ADDRESS);
+    i2c->write(highByte(REG_MEASURE_RAW));
+    i2c->write(lowByte(REG_MEASURE_RAW));
+
+    i2c->write(highByte(RH_ticks));
+    i2c->write(lowByte(RH_ticks));
+    i2c->write(CRC8(RH_ticks));
+
+    i2c->write(highByte(T_ticks));
+    i2c->write(lowByte(T_ticks));
+    i2c->write(CRC8(T_ticks));
+
+    i2c->endTransmission();
+
+    delay(30);
+
+    i2c->requestFrom(SGP40_ADDRESS, SENSOR_DATA_LENGTH);
+
+    while(i2c->available()){
+        data[ord++] = i2c->read();
+    }
+
+    return success;
+}
+
+
+/****************************************************************/
+int32_t SGP40::voc(float RH, float T){
+  if(!m_initialized) return 0;
+  uint8_t data[SENSOR_DATA_LENGTH];
+  ReadData(data, RH, T);
+  uint16_t results = (data[0]<<8) | data[1];
+  int32_t voci = 0;
+  VocAlgorithm_process(&vocAlgorithmParameters, results, &voci);
+
+  return voci;
+    
+}
+void SGP40::read(int32_t& voc, float RH, float T){
+   if(!m_initialized) return;
+  uint8_t data[SENSOR_DATA_LENGTH];
+  ReadData(data, RH, T);
+  uint16_t results = (data[0]<<8) | data[1];
+  VocAlgorithm_process(&vocAlgorithmParameters, results, &voc);
+    return;
+}
+
+/****************************************************************/
+SGP40::ChipModel SGP40::chipModel(){
+   return m_chip_model;
+}
+
+
+/****************************************************************/
+bool SGP40::WriteRegister(uint16_t addr, uint8_t data){
+  i2c->beginTransmission(SGP40_ADDRESS);
+  i2c->write(highByte(addr));
+  i2c->write(lowByte(addr));
+  i2c->write(data);
+  i2c->endTransmission();
+
+  return true;
+}
+
+
+/****************************************************************/
+bool SGP40::ReadRegister(uint8_t addr,uint8_t data[],uint8_t length){
+  uint8_t ord(0);
+
+  i2c->beginTransmission(SGP40_ADDRESS);
+  i2c->write(addr);
+  i2c->endTransmission();
+
+  i2c->requestFrom(static_cast<uint8_t>(SGP40_ADDRESS), length);
+
+  while(i2c->available()){
+    data[ord++] = i2c->read();
+  }
+
+  return ord == length;
+}
+
+
+uint8_t SGP40::CRC8(uint16_t data){
+  uint8_t crc = 0xFF;
+  crc ^= (data >> 8);
+  for (uint8_t i = 0 ; i < 8 ; i++){
+    if ((crc & 0x80) != 0) crc = (uint8_t)((crc << 1) ^ 0x31);
+    else                   crc <<= 1;
+  }
+  crc ^= (uint8_t)data;
+  for (uint8_t i = 0 ; i < 8 ; i++){
+    if ((crc & 0x80) != 0) crc = (uint8_t)((crc << 1) ^ 0x31);
+    else                   crc <<= 1;
+  }
+  return crc; 
+}