merged example with other serial strings example and rationalised name

ARDSerialSendReceive/ARDSerialSendReceive.ino → SerialSendReceiveStrings/SerialSendReceiveStrings.ino

@@ -7,15 +7,14 @@
 * Then, what data do you want from it? And how often?
 */
 
-const char stopChar = '\n'; //new line character 
+const char stopChar = '\n'; //new line character
 
-const long timeoutMs = 400; // timeout if message took too long 
+const long timeoutMs = 400; // timeout if message took too long
 
-// if matching an exact message: 
+// if matching an exact message:
 const char LEDONCommand[] = "ledon";
 const char LEDOFFCommand[] = "ledoff";
 
-
 long bytesReceived = 1;
 
 /**
@@ -37,23 +36,27 @@ void handleMessage(char *message)
 {
      // handle the command.. blink or something?
 
-     if (strcmp(message,LEDONCommand) == 0) {
-          digitalWrite(LED_BUILTIN,HIGH);
+     if (strcmp(message, LEDONCommand) == 0)
+     {
+          digitalWrite(LED_BUILTIN, HIGH);
      }
-     else if (strcmp(message,LEDOFFCommand) == 0) {
-          digitalWrite(LED_BUILTIN,LOW);
+     else if (strcmp(message, LEDOFFCommand) == 0)
+     {
+          digitalWrite(LED_BUILTIN, LOW);
      }
-     else {
-          for (int i=0; i<4; i++)
+     else
+     {
+          // flash error lights
+          for (int i = 0; i < 4; i++)
           {
-               blink(LED_BUILTIN,80);
+               blink(LED_BUILTIN, 30);
           }
      }
      ////////////////////////////////////////////////
      // useful for debugging - echo back what we got
      Serial.print('[');
      int msgLen = strlen(message);
-     for (int i=0; i< msgLen; i++)
+     for (int i = 0; i < msgLen; i++)
      {
           Serial.print(message[i]);
      }
@@ -68,99 +71,95 @@ void setup()
      //
      char cmdTest[] = {'l', 'e', 'd', 'o', 'n', '\0'};
 
+     // test:
      if (strcmp(cmdTest, LEDONCommand) == 0)
      {
-          for (int i=0; i<4; i++)
+          for (int i = 0; i < 4; i++)
           {
-               blink(LED_BUILTIN,400);
+               blink(LED_BUILTIN, 400);
           }
      }
 
      // set this as high as you can reliably run on your platform
-     Serial.begin(38400); 
+     Serial.begin(38400);
 
      // wait for serial port to be ready
-     while (!Serial);
+     while (!Serial)
+          ;
 }
 
-
+const unsigned int bufferSize = 256; // number of bytes we can read
+char buffer[bufferSize];
+int charsRead = 0; // amount of bytes we've read
 
 void loop()
 {
-     // this returns the number of bytes available to read
-     const int totalBytesToRead = Serial.available();
+     const long startTime = millis(); // time we started checking for serial
 
-     if (totalBytesToRead > 0)
+     // we need this while loop to fully empty the serial buffer
+     while (Serial.available())
      {
-          Serial.print("bytes left:");
-          Serial.println(totalBytesToRead);
-
-          int bytesToRead = totalBytesToRead;
-          const long startTime = millis(); // time we started checking for serial
+          // stop if we've taken too much time!
+          if (millis() - startTime > timeoutMs)
+          {
+               bytesToRead = 0;
 
-          // create empty message, leave room for 1 extra byte (string terminator) just in case 
-          char messageReceived[totalBytesToRead+1];
+               // flash error lights
+               for (int i = 0; i < 4; i++)
+               {
+                    blink(LED_BUILTIN, 30);
+               }
+               break;
+          }
 
-          boolean error = true; // might not get a full message...
+          char charRead = (char)Serial.read();
 
-          while (bytesToRead > 0)
+          // be careful not to go over the buffer size (with room
+          // for string terminator character)!
+          // note that this doesn't stop the loop - we ignore
+          // extra bytes
+          if (charsRead < bufferSize)
           {
-               // read the current serial values into the buffer, in order
-               // this starts at 0 and ends at the length of our buffer - 1
-               int index = totalBytesToRead - bytesToRead;
+               if (charRead != stopChar)
+               {
+                    buffer[charsRead] = charRead;
+                    charsRead = charsRead + 1;
+                    // for testing:
+                    // Serial.print(charsRead);
+               }
+               else
+               {
+                    Serial.println("process command[");
+                    Serial.print(charsRead);
+                    Serial.print("]\n");
+                    // null terminator to make a proper string:
+                    // https://www.tutorialspoint.com/cprogramming/c_strings.htm
 
-               bytesReceived++; // debugging - keep track of chars read
+                    buffer[charsRead] = '\0'; // terminate string
 
-               char newChar = (char)Serial.read();
-               
-               //we've consumed one byte from the serial buffer this loop:
-               bytesToRead = bytesToRead - 1;
+                    // process results
+                    Serial.print(':');
+                    Serial.print(buffer);
+                    Serial.println(':');
 
-               // stop if we've taken too much time!
-               if (millis() - startTime > timeoutMs){
-                    bytesToRead = 0;
-                    break;
-               } 
+                    // now handle bytes read
+                    handleMessage(messageReceived);
 
-               // check if we've received the stop character
-               if (newChar == stopChar)
-               {
-                    // echo it back
-                    // char echoStr[index+2];
-                    // strcpy(echoStr, messageReceived);
-                    // echoStr[index+1] = '\0';
-                    // Serial.println(echoStr);
-                    
-                    // handle it
-                    error = false;
-
-                    // change end character to string terminator
-                    messageReceived[index] = '\0'; // null terminator to make a proper string: https://www.tutorialspoint.com/cprogramming/c_strings.htm
-                    bytesToRead = 0;
-                    break;
-               }
-               // otherwise, just add it to the buffer
-               else {
-                    messageReceived[index] = newChar;
+                    charsRead = 0; // go back to beginning of buffer for next command
                }
-
-               // finally, keep going.
           }
-
-          if (error)
+          // otherwise too many bytes!
+          else
           {
-               for (int i=0; i<4; i++)
+               Serial.print("looped");
+               // loop back around, so we drain all serial data waiting
+               charsRead = 0;
+
+               // flash error lights
+               for (int i = 0; i < 4; i++)
                {
-                    blink(LED_BUILTIN,30);
+                    blink(LED_BUILTIN, 30);
                }
           }
-          // success! do something:
-          else {
-               // note: we might want to do this in two stages, parse first then handle
-               handleMessage(messageReceived);
-               
-               // debugging - optional
-               Serial.println(bytesReceived);
-          }
      }
 }