Incorporate pieces of DigitalAttenuator firmware in SpectrumAnalyzer.

Allows setting and reading a device ID. Gives some more robustness to input
command formatting.

common/+deviceDrivers/@SpectrumAnalyzer/SpecAnalog/SpecAnalog.ino

@@ -3,17 +3,32 @@ template<class T> inline Print &operator <<(Print &obj, T arg) {
   return obj;
 }
 
+#include <EEPROM.h>
+
 const int NO_MESSAGE = -1;
+
+// processInput states
 const byte COMMAND = 0;
 const byte NUMBER = 1;
-const byte CHANNEL = 2;
-const byte OPTIMIZE = 3;
-const byte READPOWER = 4;
-const byte DONE = 5;
+const byte DONE = 10;
+
+// command modes
+const byte READPOWER = 1; // read ADC value
+const byte GETID = 2; // get device ID
+const byte SETID = 3; // set device ID
+const byte UNKNOWN = -1;
 
 const int sensorPin = A5; // pin for analog input from log amp
 const int numAverages = 50;
-const int verbose = 0;
+
+const boolean VERBOSE = false;
+
+/**
+ * EEPROM memory map (total size = 1024 bytes)
+ * bytes 0-1: serial number
+ */
+
+ const int ID_OFFSET = 0;
 
 /* for simulating operation */
 const int simulate = 0;
@@ -34,16 +49,15 @@ void setup() {
 void loop() {
   char input[255];
   int output;
-
-  readString(input);
-  //Serial.println(input);
-  output = processInput(input);
-  if ( output == NO_MESSAGE ) {
-    Serial.println("ERROR Unknown command");
-  }
-
-  while (Serial.available() <= 0) {
-    delay(100);
+
+  if (Serial.available() > 0) {
+    readString(input);
+    if (VERBOSE) Serial.println(input);
+    output = processInput(input);
+    if ( output == NO_MESSAGE ) {
+      Serial.println("ERROR Unknown command");
+    }
+    Serial.flush();
   }
 }
 
@@ -53,14 +67,27 @@ void loop() {
 
 void readString(char* s) {
   int readCount = 0;
-  while (Serial.available() > 0 && readCount < 255) {
-    s[readCount++] = Serial.read();
+  unsigned long startTime = millis();
+  char val;
+  // terminate at 255 chars, a semicolon, or 100 ms timeout
+  while (readCount < 255 && (millis() - startTime) < 100) {
+    if (Serial.available() == 0) {
+      continue;
+    }
+    val = Serial.read();
+    if (val != '\n' && val != '\r' && val != ';') { // also ignore linefeeds and carriage returns
+      s[readCount++] = val;
+    }
+    else {
+      break;
+    }
   }
   s[readCount] = 0;
 }
 
 int processInput(char* input) {
-  byte mode = COMMAND;
+  byte mode = COMMAND; // state
+  byte command = UNKNOWN; // the interpretted command mode
   int value = NO_MESSAGE;
   char* token = strtok(input, " ");
   while (token) {
@@ -71,24 +98,47 @@ int processInput(char* input) {
     switch (mode) {
     case COMMAND:
       if (!strcasecmp(token, "READ")) {
-        value = READPOWER;
-        mode = READPOWER;
+        command = READPOWER;
+        mode = DONE;
+      }
+      if (!strcasecmp(token, "ID?")) {
+        command = GETID;
+        mode = DONE;
+      }
+      if (!strcasecmp(token, "ID")) {
+        command = SETID;
+        mode = NUMBER;
       }
       break;
     case NUMBER:
-      value = constrain(atoi(token), 0, 1023);
+      value = atoi(token);
       mode = DONE;
       break;
     }
 
     token = strtok(NULL, " ");
   }
 
-  if (mode == READPOWER) {
+  if (mode != DONE) {
+    return NO_MESSAGE;
+  }
+
+  if (command == READPOWER) {
     Serial << readPower();
     Serial.println();
+    return DONE;
+  } else if (command == GETID) {
+    Serial << getID();
+    Serial.println();
+    return DONE;
+  } else if (command == SETID) {
+    Serial << "Setting board ID to " << value;
+    Serial.println();
+    setID(value);
+    return DONE;
+  } else {
+    return NO_MESSAGE;
   }
-  return DONE;
 }
 
 double analogReadAverage(int pin, int numavg) {
@@ -108,3 +158,18 @@ double readPower() {
   return analogReadAverage(sensorPin, numAverages);
 }
 
+// get first two bytes from EEPROM memory
+unsigned int getID(void) {
+  unsigned int id = word( EEPROM.read(ID_OFFSET+1), EEPROM.read(ID_OFFSET) );
+  return id;
+}
+
+// write ID into first two bytes of EEPROM memory
+void setID(unsigned int id) {
+  if (VERBOSE) {
+    Serial << "Low Byte 0: " << (id & 0xFF) << "\n";
+    Serial << "High Byte 1: " << (id >> 7) << "\n";
+  }
+  EEPROM.write(ID_OFFSET, id & 0xFF);
+  EEPROM.write(ID_OFFSET+1, (id >> 7) );
+}