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--- bauteile:thermokamera [2017/12/22 14:36]
d.golovko [Installation]
+++ bauteile:thermokamera [2018/02/07 16:25] (aktuell)
d.golovko
@@ Zeile 8: / Zeile 8: @@
 Hier findet ihr das Datenblatt: [[http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90620-776.aspx|http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/MLX90620-776.aspx]].\\
-=== Kommunikation mit dem Microcontroller===
-Die Kamera kommuniziert über ein [[http://de.wikipedia.org/wiki/I%C2%B2C|I2C]] Interface mit einem angeschlossenen Microcontroller.
 ==== Installation ====
 Die Kamera läuft auf einer recht niedrigen Spannung von 2.6V und ist deshalb nur mit etwas Aufwand mit einem 5V Arduino zusammen zu betreiben.
 Einfacher funktioniert es mit einem der [[bauteile:teensy3|Teensy3.0++]], die wir im Labor haben. Die sind auch gleich schnell genug, um die Temperaturen mit einer akzetablen Geschwindigkeit und Präzision zu berechnen.
+Ein Teensy liefert 3.3V. D.h. um die Kamera nicht zu beschädigen, müsst ihr die Spanung begrenzen.[[https://pavlov.tech/2015/05/15/detecting-crying-eyes/|Hier]] gibt es eine Beispielschaltung zu sehen.
+== Code-Beispiel ==
+Dieses Beispiel ist eine Modifikation von http://forum.arduino.cc/index.php?topic=122306.0
+<code cpp>
+/*****************************************************************
+   This code is design to interface with the MLX90621 sensor.
+   This sensor is a Low noise High Speed 16x4 Far Infrared array.
+   Here is used to obtain data for making a thermal sensor.
+   More information is available here: http://www.melexis.com/Infrared-Thermometer-Sensors/Infrared-Thermometer-Sensors/Low-noise-high-speed-16x4-Far-Infrared-array-823.aspx
+   Pixel position:
+   The array consists of 64 IR sensors (also called pixels). Each pixel is identified with its row and
+   column position as Pix(i,j) where i is its row number (from 0 to 3) and j is its column number (from 0 to 15)
+   RAM:
+   The on chip 146x16 RAM is accessible for reading via I2C. The RAM is used for storing the results of
+   measurements of pixels and Ta sensor and is distributes as follows:
+words for IR sensors. The data is in 2’s complement format
+word for measurement result of PTAT sensor. The data is 16 bit without sign.
+   The memory map of the RAM is shown below:
+x00=IR Sensor(0,0) result
+x01=IR Sensor(1,0) result
+x02=IR Sensor(2,0) result
+x03=IR Sensor(3,0) result
+x04=IR Sensor(0,1) result
+x05=IR Sensor(1,1) result
+   ...
+x3B=IR Sensor(3,14) result
+x3C=IR Sensor(0,15) result
+x3D=IR Sensor(1,15) result
+x3E=IR Sensor(2,15) result
+x3F=IR Sensor(3,15) result
+   Device Addressing:
+   For accessing to internal EEPROM: 0x50
+   For accessing to IR array data:   0x60
+*/
+//Libraries to be included
+#include <Arduino.h>
+#include <Wire.h>
+//Begin registers
+#define CAL_ACOMMON_L 0xD0
+#define CAL_ACOMMON_H 0xD1
+#define CAL_ACP_L 0xD3
+#define CAL_ACP_H 0xD4
+#define CAL_BCP 0xD5
+#define CAL_alphaCP_L 0xD6
+#define CAL_alphaCP_H 0xD7
+#define CAL_TGC 0xD8
+#define CAL_AI_SCALE 0xD9
+#define CAL_BI_SCALE 0xD9
+#define VTH_L 0xDA
+#define VTH_H 0xDB
+#define KT1_L 0xDC
+#define KT1_H 0xDD
+#define KT2_L 0xDE
+#define KT2_H 0xDF
+#define KT_SCALE 0xD2
+//Common sensitivity coefficients
+#define CAL_A0_L 0xE0
+#define CAL_A0_H 0xE1
+#define CAL_A0_SCALE 0xE2
+#define CAL_DELTA_A_SCALE 0xE3
+#define CAL_EMIS_L 0xE4
+#define CAL_EMIS_H 0xE5
+//Config register = 0xF5-F6
+#define OSC_TRIM_VALUE 0xF7
+/* Variables */
+const byte refreshRate = 1; //Set this value to your desired refresh frequency. Possible values: 0=0.5Hz, 1=1Hz, 2=2Hz, 4=4Hz, 8=8Hz, 16=16Hz, 32=32Hz.
+int16_t irData[64]; //Contains the raw IR data from the sensor
+float temperatures[64]; //Contains the calculated temperatures of each pixel in the array
+byte eepromData[256]; //Contains the full EEPROM reading from the MLX90621
+int16_t k_t1_scale = 0, k_t2_scale = 0, resolution = 0, configuration = 0, cpix = 0;
+uint16_t  ptat = 0;
+// modified:
+int16_t irDataAtStart[64];
+void setup()
+{
+  Serial.begin(115200);
+  Wire.begin();
+  delay(5);
+  readEEPROM();
+  writeTrimmingValue();
+  setConfiguration();
+  // the initial values obtained by the camera are read. They are then substracted from the measured values.
+  // This way, if there is no temperature change compared to the observation start, the Serial Monitor
+  // will display an array of 0.
+  readIR();
+  for (int i = 0; i<64; i++) {
+    irDataAtStart[i] = irData[i];
+  }
+}
+void loop()
+{
+  if (checkConfig())
+  {
+    readEEPROM();
+    writeTrimmingValue();
+    setConfiguration();
+  }
+  for (int i = 0; i < 16; i++) //Every 16 readings check that the POR flag is not set
+  {
+    readIR();
+    Serial.println();
+    Serial.println();
+    delay(1000);
+  }
+}
+void readEEPROM()
+{
+  int i = 0;
+  Serial.print("\nReading EEPPROM...");
+  for (int j = 0; j < 256; j = j + 32)
+  {
+    Wire.beginTransmission(0x50);
+    Wire.write((byte)j);
+    //Wire.endTransmission(false); // use repeated start to get answer
+    Wire.requestFrom(0x50, 32);
+    i = j;
+    Serial.print("\n["); Serial.print(j); Serial.print("] ");
+    while ( Wire.available() )
+    { // slave may send less than requested
+      eepromData[i] = (byte)Wire.read();
+      Serial.print(eepromData[i]); Serial.print(" ");
+      i++;
+    }
+    Wire.endTransmission();
+  }
+  Serial.println(" ");
+}
+void writeTrimmingValue()
+{
+  Serial.print("\nWriting Trimming Value...");
+  Wire.beginTransmission(0x60);
+  Wire.write(0x04);
+  Wire.write((byte)eepromData[OSC_TRIM_VALUE] - 0xAA);
+  Wire.write(eepromData[OSC_TRIM_VALUE]);//eepromData[0xF7]
+  Wire.write(0x100 - 0xAA); //0x56
+  Wire.write(0x00);
+  I2Canswer(Wire.endTransmission());
+}
+void setConfiguration()
+{
+  Serial.print("\nSetting configuration...");
+  byte Hz_LSB;
+  switch (refreshRate)
+  {
+    case 0:
+      Hz_LSB = 0b00111111;
+      break;
+    case 1:
+      Hz_LSB = 0b00111110;
+      break;
+    case 2:
+      Hz_LSB = 0b00111101;
+      break;
+    case 4:
+      Hz_LSB = 0b00111100;
+      break;
+    case 8:
+      Hz_LSB = 0b00111011;
+      break;
+    case 16:
+      Hz_LSB = 0b00111010;
+      break;
+    case 32:
+      Hz_LSB = 0b00111001;
+      break;
+    default:
+      Hz_LSB = 0b00111110;
+  }
+  //byte defaultConfig_H =0b00000100; //0x04;//0b00000100;
+  byte defaultConfig_H = 0b00000110;
+  Wire.beginTransmission(0x60);
+  Wire.write(0x03);
+  Wire.write((byte)Hz_LSB - 0x55);
+  Wire.write(Hz_LSB);
+  Wire.write(defaultConfig_H - 0x55);//0x14-0x55
+  Wire.write(defaultConfig_H);
+  I2Canswer(Wire.endTransmission());
+  //Read the resolution from the config register
+  resolution = (readConfig() & 0x30) >> 4;
+  Serial.print("Resolution: "); Serial.println(resolution); delay(100);
+}
+/*****************************************************
+  IR  data of the device that it is read by lines
+  by using the following function.
+ *****************************************************/
+void readIR()
+{
+  int i = 0;
+  Serial.print("Reading IRsensor:");
+  // Due to wire library buffer limitations, we can only read up to 32 bytes at a time
+  // Thus, the request has been split into multiple different requests to get the full 128 values
+  // Each pixel value takes up two bytes (???) thus NUM_PIXELS * 2
+  for (int line = 0; line < 4; line++) //4 pixels lines
+  {
+    Serial.print("\n["); Serial.print(line); Serial.print("] ");
+    Wire.beginTransmission(0x60);//Sensor Address
+    Wire.write(0x02);//CMD_Sensor_Read
+    Wire.write(line);//lines:0x00,0x01,0x02,0x03
+    Wire.write(0x04);//0x04
+    Wire.write(0x10);//0x10
+    Wire.endTransmission(false);
+    Wire.requestFrom(0x60, 32);//16 pixels per column x 2 bytes per pixel
+    for (int j = 0; j < 16; j++)
+    {
+      // We read two bytes
+      byte pixelDataLow = Wire.read();
+      byte pixelDataHigh = Wire.read();
+      irData[i] = (int16_t) ((pixelDataHigh << 8) | pixelDataLow);
+      Serial.print(irData[i] - irDataAtStart[i]); Serial.print(" "); // modified
+      i++;
+    }
+  }
+  I2Canswer(Wire.endTransmission());
+}
+void I2Canswer(int opcion)
+{
+  switch (opcion)
+  {
+    case 0:
+      Serial.print(" Success. ");
+      break;
+    case 1:
+      Serial.print(" Data too long to fit in transmit buffer. ");
+      break;
+    case 2:
+      Serial.print(" Received NACK on transmit of address. ");
+      break;
+    case 3:
+      Serial.print(" Received NACK on transmit of data. ");
+      break;
+    default:
+      Serial.print(" Other error. ");
+  }
+}
+float getTemperature(int num)
+{
+  if ((num >= 0) && (num < 64)) return temperatures[num];
+  else                    return NULL;
+}
+//Poll the MLX90621 for its current status
+//Returns true if the POR/Brown out bit is set
+boolean checkConfig() //Every 16 readings check that the POR flag is not set
+{
+  bool check = !((readConfig() & 0x0400) >> 10);
+  return check;
+}
+/****************************************************
+  Configuration Registers of the device can be read
+  by using the following function.
+ ****************************************************/
+int16_t readConfig()
+{
+  int i = 0;
+  byte configLow = 0, configHigh = 0;
+  Serial.print("\nReading Configuration...");
+  Wire.beginTransmission(0x60);
+  Wire.write(0x02);
+  Wire.write(0x92);
+  Wire.write(0x00);
+  Wire.write(0x01);
+  I2Canswer(Wire.endTransmission(false)); // use repeated start to get answer   )
+  Wire.requestFrom(0x60, 2);
+  while ( Wire.available() )
+  {
+    i++;
+    byte configLow = Wire.read();
+    byte configHigh = Wire.read();
+    if (i > 2) Serial.print("Error reading Config");
+  }
+  I2Canswer(Wire.endTransmission()); // use repeated start to get answer   )
+  configuration = ((int16_t) (configHigh << 8) | configLow);
+  Serial.print("Configuration:"); Serial.print(configHigh); Serial.println(configLow);
+  return configuration;
+}
-Felix hat dafür eine Library geschrieben und ins Netz gestellt: [[https://github.com/Zapalot/teensy3_Melexis90620/]]. Ladet dort die .zip Datei herunter und entpackt sie in euer Arduino/libraries Verzeichnis. Benennt dann das entpackte Verzeichnis in einen Namen ohne das "-master" um.
-Das Beispielprogramm in der Library enthält auch gleich eine Anleitung, wie der Sensor anzuschließen ist.
-Zusätzlich braucht Ihr die [[http://forum.pjrc.com/threads/21680-New-I2C-library-for-Teensy3|t3_i2c]] Library, die die Verwendung von I2C auf dem Teensy3.0 vereinfacht ([[https://github.com/nox771/i2c_t3|Download Link]]).
+</code>

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