temp: [#61] Make things a little clearer.

* Newline in log isn't nice.
* I managed to confuse even myself with this 0x4a.
It's actually not used anywhere currently.

source/shoh/src/threads/temperature/SensorTempSHT20.cpp

@@ -0,0 +1,128 @@
+/*
+ * SensorTempSHT20.cpp
+ *
+ *  Created on: 16 May 2023
+ */
+
+#include "SensorTempSHT20.h"
+#include "FreeRTOS.h"
+#include "task.h"
+#include "Log.h"
+
+//D6U9H:
+//D - Digital (i2c)
+//6 - 2016 year of production
+//U9H - Sensirion undecodable crap
+//Address: 0x40
+
+//Trigger T measurement | hold master    | 1110 0011 - 0xe3 (implemented)
+//Trigger T measurement | no hold master | 1111 0011 - 0xf3
+//Write user register   |                | 1110 0110 - 0xe6
+//Read user register    |                | 1110 0111 - 0xe7
+//Soft reset            |                | 1111 1110 - 0xfe
+
+
+SensorTempSHT20::SensorTempSHT20(I2C* pi2c)
+: _pi2c(pi2c), _dev_addr(0x40), _up_flag(false),
+_com_read_hold(0xe3), _com_read_nohold(0xf3),
+_com_write_ur(0xe6), _com_read_ur(0xe7),
+_com_soft_reset(0xfe), _polynominal(0x131)
+{
+  //Read sensor during the initialisation to get the "UP" state earlier.
+  this->read();
+}
+
+SensorTempSHT20::~SensorTempSHT20()
+{}
+
+/**
+ * @brief Gets temperature from SHT20 sensor.
+ * 
+ * @return int8_t temperature value trimmed from -128 to 127.
+ */
+int8_t SensorTempSHT20::getTemperature()
+{
+  uint16_t raw_temp = this->read();
+  bool err_bit = raw_temp & 0x1;
+  int temp = 0;
+  if (err_bit)
+    return -128;
+
+  //Formula: (St / 2 ^ 16) * 175.72 - 46.85
+  temp = ((double)raw_temp / 65536) * 175.72 - 46.85;
+
+  if(temp > 127)
+    temp = 127;
+  if (temp < -128)
+    temp = -128;
+
+  return temp;
+}
+
+/**
+ * @brief Makes sure that the sensor is up.
+ * 
+ * @return true It is.
+ * @return false It is not.
+ */
+bool SensorTempSHT20::is_up()
+{
+  this->read();
+  return this->_up_flag;
+}
+
+//Use hold master - read(com = 0xe3)
+//Reading is done via 3 bytes.
+//WRITE: I2C address + write | read command
+//READ: Data (MSB) | Data (LSB) + Stat. | Checksum
+/**
+ * @brief Gets raw temperature measurement data from sensor
+ * using hold master mode.
+ * 
+ * @return uint16_t Raw temperature measurement data.
+ */
+uint16_t SensorTempSHT20::read()
+{
+  uint8_t  tbuf = this->_com_read_hold;
+  uint8_t  rbuf[3] = {0x0, 0x2, 0x0};
+  uint8_t crc = 0x0;
+  uint16_t  raw_temp = 0;
+  this->_up_flag = this->_pi2c->transaction(this->_dev_addr, &tbuf, 1, rbuf, 3);
+  
+  //Sensor changes this bit to 0 on temp measurement.
+  if (rbuf[1] & 0x2)
+    return 0x1;
+
+  raw_temp |= (rbuf[0] << 8);
+  raw_temp |= (rbuf[1] & 0xfc);
+  crc = rbuf[2];
+
+  if (this->crc_check(rbuf, 2, crc))
+    LOG_WARNING("Temperature sensor reported crc mismatch. Raw data: %04x; CRC: %x", raw_temp, crc);
+  
+  return raw_temp;
+}
+
+/**
+ * @brief Checks if checksum is correct.
+ * 
+ * @param data array of raw data to check.
+ * @param nbrOfBytes size of an array.
+ * @param checksum received checksum to compare calculated crc to.
+ * @return true - checksum is incorrect.
+ * @return false - checksum is the same as calculated.
+ */
+bool SensorTempSHT20::crc_check(uint8_t * data, uint8_t nbrOfBytes, uint8_t checksum)
+{
+  uint8_t crc = 0;
+  uint8_t bit;
+  uint8_t byteCtr;
+  //Calculates 8-Bit checksum with given _polynomial
+  for (byteCtr = 0; byteCtr < nbrOfBytes; ++byteCtr)
+  {
+    crc ^= (data[byteCtr]);
+    for ( bit = 8; bit > 0; --bit)
+      crc = (crc & 0x80) ? ((crc << 1) ^ this->_polynominal) : (crc << 1);
+  }
+  return crc != checksum;
+}

source/shoh/src/threads/temperature/SensorTempSHT20.h

@@ -0,0 +1,34 @@
+/*
+ * SensorTempSHT20.h
+ *
+ *  Created on: 16 May 2023
+ */
+
+#ifndef THREADS_TEMPERATURE_SENSORTEMPTC74_H_
+#define THREADS_TEMPERATURE_SENSORTEMPTC74_H_
+
+#include "I2C.h"
+#include "chip.h"
+
+class SensorTempSHT20 {
+public:
+  SensorTempSHT20(I2C* pi2c);
+  virtual ~SensorTempSHT20();
+  int8_t getTemperature();
+  bool is_up();
+private:
+  uint16_t read();
+  bool crc_check(uint8_t * data, uint8_t nbrOfBytes, uint8_t checksum);
+
+  I2C* _pi2c;
+  const uint8_t _dev_addr;
+  bool _up_flag;
+  const uint8_t _com_read_hold;
+  const uint8_t _com_read_nohold;
+  const uint8_t _com_write_ur; //user register
+  const uint8_t _com_read_ur; //user register
+  const uint8_t _com_soft_reset;
+  const uint16_t _polynominal;
+};
+
+#endif /* THREADS_TEMPERATURE_SENSORTEMPSHT20_H_ */

source/shoh/src/threads/temperature/Temperature.cpp

@@ -5,7 +5,8 @@
  */
 
 #include "Temperature.h"
-#include "SensorTempTC74.h"
+//#include "SensorTempTC74.h"
+#include "SensorTempSHT20.h"
 #include "Event.h"
 #include "Log.h"
 
@@ -15,7 +16,8 @@ Temperature::~Temperature() {}
 
 void Temperature::taskFunction()
 {
-	SensorTempTC74 ext_temp_sensor(this->_pi2c, 0x4a);
+	//SensorTempTC74 ext_temp_sensor(this->_pi2c, 0x4a);
+	SensorTempSHT20 ext_temp_sensor(this->_pi2c);
 	Event t (Event::ExternalTemp, -128);
 	int8_t temp_value = -128;
 	_qm->send<Event>(ThreadCommon::QueueManager::master_event_all, &t, 0);
@@ -41,7 +43,7 @@ void Temperature::taskFunction()
 void thread_temperature(void* pvParams)
 {
 	ThreadCommon::CommonManagers * manager = static_cast<ThreadCommon::CommonManagers*>(pvParams);
-	I2C_config conf{0x4a, 100000};
+	I2C_config conf{0, 100000};
 	I2C i2c(conf);
 	Temperature t(manager->qm, &i2c);
 	t.taskFunction();