Arduino sketch added

arduino_sketch/ReflectorLightBarrier.ino

@@ -0,0 +1,220 @@
+/*
+* Program to read the electrical meter using a reflective light sensor
+* This is the data acquisition part running on an Arduino Nano.
+* It controls the infrared light barrier, detects trigger
+* and communicates with a master computer (Raspberry Pi)
+* over USB serial.
+
+* Copyright 2015 Martin Kompf
+*
+* This program is free software: you can redistribute it and/or modify
+* it under the terms of the GNU General Public License as published by
+* the Free Software Foundation, either version 3 of the License, or
+* (at your option) any later version.
+* 
+* This program is distributed in the hope that it will be useful,
+* but WITHOUT ANY WARRANTY; without even the implied warranty of
+* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+* GNU General Public License for more details.
+* 
+* You should have received a copy of the GNU General Public License
+* along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <avr/eeprom.h>
+
+const int analogInPin = A7;  // Analog input pin that the photo transistor is attached to
+const int irOutPin = 2; // Digital output pin that the IR-LED is attached to
+const int ledOutPin = 12; // Signal LED output pin
+
+int sensorValueOff = 0;  // value read from the photo transistor when ir LED is off
+int sensorValueOn = 0;  // value read from the photo transistor when ir LED is on
+
+// command line
+#define MAX_CMD_LEN 80
+char command[MAX_CMD_LEN]; // command buffer
+int inCount = 0; // command buffer index
+boolean cmdComplete = false;
+
+// Mode of serial line: 
+// C - command, D - data output
+char mode = 'D';
+
+// Data output mode:
+// R - raw data
+// T - trigger events
+// C - counter
+char dataOutput = 'T';
+
+// trigger state and level
+int triggerLevelLow;
+int triggerLevelHigh;
+boolean triggerState = false;
+
+// Address of trigger levels in EEPROM
+uint16_t triggerLevelLowAddr = 0;
+uint16_t triggerLevelHighAddr = 4;
+
+/**
+ * Set trigger levels (low high) from the command line
+ * and store them into EEPROM
+ */
+void setTriggerLevels() {
+  char *p = &command[1];
+  while (*p != 0 && *p == ' ') {
+    ++p;
+  }
+  char *q = p + 1;
+  while (*q != 0 && *q != ' ') {
+    ++q;
+  }
+  *q = 0;
+  eeprom_write_word(&triggerLevelLowAddr, atoi(p));
+  
+  p = q + 1;
+  while (*p != 0 && *p == ' ') {
+    ++p;
+  }
+  q = p + 1;
+  while (*q != 0 && *q != ' ') {
+    ++q;
+  }
+  *q = 0;
+  eeprom_write_word(&triggerLevelHighAddr, atoi(p));
+}
+
+/**
+ * Read trigger levels from EEPROM
+ */
+void readTriggerLevels() {
+  triggerLevelLow = (int)eeprom_read_word(&triggerLevelLowAddr);
+  triggerLevelHigh = (int)eeprom_read_word(&triggerLevelHighAddr);
+  Serial.print("Trigger levels: ");
+  Serial.print(triggerLevelLow);
+  Serial.print(" ");
+  Serial.println(triggerLevelHigh);
+}
+
+/**
+ * Detect and print a trigger event
+ */
+void detectTrigger(int val) {
+  boolean nextState = triggerState;
+  if (val > triggerLevelHigh) {
+    nextState = true;
+  } else if (val < triggerLevelLow) {
+    nextState = false;
+  }
+  if (nextState != triggerState) {
+    triggerState = nextState;
+    Serial.println(triggerState? 1 : 0);
+    // control internal LED
+    digitalWrite(ledOutPin, triggerState);
+  }
+}
+
+/**
+ * Read one line from serial connection and interpret it as a command
+ */
+void doCommand() {
+  // print prompt 
+  Serial.print(">");
+  while (! cmdComplete) {
+    // read input
+    while (Serial.available()) {
+      // get the new byte:
+      char inChar = (char)Serial.read();
+      if (inChar == '\n' || inChar == '\r') {
+        command[inCount] = 0;
+        Serial.println();
+        cmdComplete = true;
+        break; // End of line
+      } else if (inCount < MAX_CMD_LEN - 1) {
+        command[inCount] = inChar;
+        inCount++;
+        // echo
+        Serial.print(inChar);
+      }
+    }
+  }
+  
+  // interprete command
+  switch (command[0]) {
+    case 'D':
+      // start raw data mode
+      mode = 'D';
+      dataOutput = 'R';
+      break;
+    case 'T':
+      // start trigger data mode
+      mode = 'D';
+      dataOutput = 'T';
+      break;
+    case 'S':
+      // set trigger levels
+      setTriggerLevels();
+      readTriggerLevels();
+      break;
+  }
+  
+  // clear command buffer
+  command[0] = 0;
+  inCount = 0;
+  cmdComplete = false;
+}
+
+/**
+ * Setup.
+ */
+void setup() {
+  // initialize serial communications at 9600 bps:
+  Serial.begin(9600);
+  // initialize the digital pins as an output.
+  pinMode(irOutPin, OUTPUT);
+  pinMode(ledOutPin, OUTPUT);
+  // read config from EEPROM
+  readTriggerLevels();
+}
+
+/**
+ * Main loop.
+ */
+void loop() {
+  if (mode == 'C') {
+    doCommand();
+  } else if (mode == 'D') {
+    if (Serial.available()) {
+      char inChar = (char)Serial.read();
+      if (inChar == 'C') {
+        // exit data mode
+        mode = 'C';
+      }
+    }
+  }
+  if (mode == 'D') {
+    // perform measurement
+    // turn IR LED off
+    digitalWrite(irOutPin, LOW);
+    // wait 10 milliseconds
+    delay(10);
+    // read the analog in value:
+    sensorValueOff = analogRead(analogInPin);           
+    // turn IR LED on
+    digitalWrite(irOutPin, HIGH);
+    delay(10);
+    // read the analog in value:
+    sensorValueOn = analogRead(analogInPin);           
+    
+    switch (dataOutput) {
+      case 'R':
+        // print the raw data to the serial monitor         
+        Serial.println(sensorValueOn - sensorValueOff);
+        break;
+      case 'T':
+        // detect and output trigger
+        detectTrigger(sensorValueOn - sensorValueOff);
+        break;
+    }
+  }
+  delay(10);                     
+}