v2.9

lib/Adafruit MLX90614 Library/Adafruit_MLX90614.cpp

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+/***************************************************
+  This is a library for the MLX90614 Temp Sensor
+
+  Designed specifically to work with the MLX90614 sensors in the
+  adafruit shop
+  ----> https://www.adafruit.com/products/1747 (3V)
+  ----> https://www.adafruit.com/products/1748 (5V)
+
+  These sensors use I2C to communicate, 2 pins are required to
+  interface
+  Adafruit invests time and resources providing this open source code,
+  please support Adafruit and open-source hardware by purchasing
+  products from Adafruit!
+
+  Written by Limor Fried/Ladyada for Adafruit Industries.
+  BSD license, all text above must be included in any redistribution
+ ****************************************************/
+
+#include "Adafruit_MLX90614.h"
+
+Adafruit_MLX90614::~Adafruit_MLX90614() {
+  if (i2c_dev)
+    delete i2c_dev;
+}
+
+/**
+ * @brief Begin the I2C connection
+ * @param addr I2C address for the device.
+ * @param wire Pointer to Wire instance
+ * @return True if the device was successfully initialized, otherwise false.
+ */
+bool Adafruit_MLX90614::begin(uint8_t addr, TwoWire *wire) {
+  _addr = addr; // needed for CRC
+  if (i2c_dev)
+    delete i2c_dev;
+  i2c_dev = new Adafruit_I2CDevice(addr, wire);
+  return i2c_dev->begin();
+}
+
+/**
+ * @brief Read the raw value from the emissivity register
+ *
+ * @return uint16_t The unscaled emissivity value or '0' if reading failed
+ */
+uint16_t Adafruit_MLX90614::readEmissivityReg(void) {
+  return read16(MLX90614_EMISS);
+}
+/**
+ * @brief Write the raw unscaled emissivity value to the emissivity register
+ *
+ * @param ereg The unscaled emissivity value
+ */
+void Adafruit_MLX90614::writeEmissivityReg(uint16_t ereg) {
+  write16(MLX90614_EMISS, 0); // erase
+
+  vTaskDelay(10);
+  write16(MLX90614_EMISS, ereg);
+
+  vTaskDelay(10);
+}
+/**
+ * @brief Read the emissivity value from the sensor's register and scale
+ *
+ * @return double The emissivity value, ranging from 0.1 - 1.0 or NAN if reading
+ * failed
+ */
+double Adafruit_MLX90614::readEmissivity(void) {
+  uint16_t ereg = read16(MLX90614_EMISS);
+  if (ereg == 0)
+    return NAN;
+  return ((double)ereg) / 65535.0;
+}
+/**
+ * @brief Set the emissivity value
+ *
+ * @param emissivity The emissivity value to use, between 0.1 and 1.0
+ */
+void Adafruit_MLX90614::writeEmissivity(double emissivity) {
+  uint16_t ereg = (uint16_t)(0xffff * emissivity);
+ 
+  writeEmissivityReg(ereg);
+}
+
+/**
+ * @brief Get the current temperature of an object in degrees Farenheit
+ *
+ * @return double The temperature in degrees Farenheit or NAN if reading failed
+ */
+double Adafruit_MLX90614::readObjectTempF(void) {
+  return (readTemp(MLX90614_TOBJ1) * 9 / 5) + 32;
+}
+/**
+ * @brief Get the current ambient temperature in degrees Farenheit
+ *
+ * @return double The temperature in degrees Farenheit or NAN if reading failed
+ */
+double Adafruit_MLX90614::readAmbientTempF(void) {
+  return (readTemp(MLX90614_TA) * 9 / 5) + 32;
+}
+
+/**
+ * @brief Get the current temperature of an object in degrees Celcius
+ *
+ * @return double The temperature in degrees Celcius or NAN if reading failed
+ */
+double Adafruit_MLX90614::readObjectTempC(void) {
+  return readTemp(MLX90614_TOBJ1);
+}
+
+/**
+ * @brief Get the current ambient temperature in degrees Celcius
+ *
+ * @return double The temperature in degrees Celcius or NAN if reading failed
+ */
+double Adafruit_MLX90614::readAmbientTempC(void) {
+  return readTemp(MLX90614_TA);
+}
+
+float Adafruit_MLX90614::readTemp(uint8_t reg) {
+  float temp;
+
+  temp = read16(reg);
+  if (temp == 0)
+    return NAN;
+  temp *= .02;
+  temp -= 273.15;
+  return temp;
+}
+
+/*********************************************************************/
+
+uint16_t Adafruit_MLX90614::read16(uint8_t a) {
+  uint8_t buffer[3];
+  buffer[0] = a;
+  // read two bytes of data + pec
+  bool status = i2c_dev->write_then_read(buffer, 1, buffer, 3);
+  if (!status)
+    return 0;
+  // return data, ignore pec
+  return uint16_t(buffer[0]) | (uint16_t(buffer[1]) << 8);
+}
+
+byte Adafruit_MLX90614::crc8(byte *addr, byte len)
+// The PEC calculation includes all bits except the START, REPEATED START, STOP,
+// ACK, and NACK bits. The PEC is a CRC-8 with polynomial X8+X2+X1+1.
+{
+  byte crc = 0;
+  while (len--) {
+    byte inbyte = *addr++;
+    for (byte i = 8; i; i--) {
+      byte carry = (crc ^ inbyte) & 0x80;
+      crc <<= 1;
+      if (carry)
+        crc ^= 0x7;
+      inbyte <<= 1;
+    }
+  }
+  return crc;
+}
+
+void Adafruit_MLX90614::write16(uint8_t a, uint16_t v) {
+  uint8_t buffer[4];
+
+  buffer[0] = _addr << 1;
+  buffer[1] = a;
+  buffer[2] = v & 0xff;
+  buffer[3] = v >> 8;
+
+  uint8_t pec = crc8(buffer, 4);
+
+  buffer[0] = buffer[1];
+  buffer[1] = buffer[2];
+  buffer[2] = buffer[3];
+  buffer[3] = pec;
+
+  i2c_dev->write(buffer, 4);
+
+}