Serial ports on Due

Official Hardware Mega Due
1

Hi all

I have been testing some codes on my Mega board with a couple of RoboteQ motor controllers and all is going well, I have Serial1 conected to one motor controller and Serial2 to the other, the Mega is requesting and receiving the telemetry from both controller and printing it on the terminal window in real time.
As I have a Due board which is much faster than the Mega I tried to do the same thing with it but I am not getting any print on the terminal window!!!
Is this a problem of the Due with serial ports or a lack of compatibility with the IDE and the Due?
In the mean time I'll try to connect an oLed screen to the Due to double check this issue but I would like to get a feedback from you.

Thanks

2

On the Mega, the first serial port is connected to the USB and pins 0 and 1.

On the Due, the first serial port is the native USB port, which doesn't have any 'real' serial pins to connect to. Serial 1 is connected to the programming port.

3

That isn't quite right, the native USB 'serial' port is SerialUSB, the first serial port is via the Programming USB port. Serial1 is connected to header pins (as are Serial2 and Serial3).

4

Well, with that said, what's the solution, if there is one?

Thanks

5

Plug into the programming port to see Serial output.

6

Hi, I was plugged to the programing port all the time and I have no prints being shown on the serial monitor, I mean, if I create a line like Serial.println("hello"); it is printed but if I do like Serial.println(count); which is the encoder comming from the motor controller on Serial1 nothing is printed... but it works on the Mega board perfectly.

Cheers

7

Can you post the code?

8 
const char maskSerial= B00000001;
const char maskStall = B00010000;
const char maskLimit = B00100000;

const char maskOverT  = B00000001;
const char maskOverV  = B00000010;
const char maskUnderV = B00000100;
const char maskShort  = B00001000;
const char maskEmerg  = B00010000;

long pauseBlink = 0;
int pauseLedStatus = LOW;

const int swPause = 2;         // switch System Pause
const int swDirection = 3;     // switch Dolly Direction
const int swUnitSelector = 24; // switch Display Unit Selector
const int swPedalCenter = 26;  // switch Pedal Center Selector

long lastDebounceTime = 0;     //  the last time the output pin was toggled
long debounceDelay = 50;       // required debounce delay
int lastSwPause = HIGH;
int lastSwDirection = HIGH;
int lastSwUnitSelector = HIGH;
int lastSwPedalCenter = HIGH;
int tmpReading;

int sensorValue = 0;          // value read from the pedal Potentiometer
int sensorScaler = 0;         // value read from the scaler Potentiometer
int sensorOffset = 0;         // offset for the Potentiometer
int outputValue = 0;          // value output to Motor
boolean Direction = true;
boolean Paused=false;
boolean Emergency=false;

int fFault = 0;                // Fault Flag 
int fStatus = 0;               // Status Flag

String inputString;               // a string to hold incoming data
boolean stringComplete = false;

int loopCnt = 0;
float dispVoltage1 = 0.0;
float dispMotAmps1 = 0.0;
float dispTemp1 = 0.0;
int dispCount1 = 0;

//===============  VOID SETUP  ====================

void setup() {
  Serial.begin(9600);
  Serial.println("Initializing...");

  pinMode(ledPower, OUTPUT); 
  pinMode(ledOverVolt, OUTPUT); 
  pinMode(ledUnderVolt, OUTPUT); 
  pinMode(ledOverTemp, OUTPUT); 
  pinMode(ledShort, OUTPUT); 
  pinMode(ledSerialCom, OUTPUT); 
  pinMode(ledStall, OUTPUT); 
  pinMode(ledErgencyStop, OUTPUT); 
  pinMode(ledLimitSwitch, OUTPUT); 
  pinMode(ledPause, OUTPUT); 

  pinMode(swPause, INPUT_PULLUP);
  pinMode(swDirection, INPUT_PULLUP);
  pinMode(swUnitSelector, INPUT_PULLUP);
  pinMode(swPedalCenter, INPUT_PULLUP); 

  Serial.println("Led Check...");
  Serial.println("Display Check...");
  Serial1.begin(115200);
  Serial2.begin(115200);
 

  //Reserve 128 bytes for the serial input String
  inputString.reserve(128);
  stringComplete = false;
  loopCnt = 0;
  Serial.println("Ready!");
  analogWrite(ledPower, 64);
}

//===============  VOID LOOP  ====================

void loop() {
  // ================================   Switch PAUSE
  tmpReading = digitalRead(swPause);
  if (tmpReading != lastSwPause)
      lastDebounceTime = millis();
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if(tmpReading==LOW)
      Paused = true;
    else
      Paused = false;
  }
  lastSwPause = tmpReading;
  
  // ================================   Switch Direction
  tmpReading = digitalRead(swDirection);
  if (tmpReading != lastSwDirection)
      lastDebounceTime = millis();
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if(tmpReading==LOW)
      Direction = false;
    else
      Direction = true;
  }
  lastSwDirection = tmpReading;


  // =================================   Center Potenziometer Switch
  tmpReading = digitalRead(swPedalCenter);
  if (tmpReading != lastSwPedalCenter)
      lastDebounceTime = millis();
  if ((millis() - lastDebounceTime) > debounceDelay) {
    if(tmpReading==LOW)
      sensorOffset = sensorValue - 512;
  }
  lastSwPedalCenter = tmpReading;

  
  // =================================   read the analog in value:
  sensorValue = analogRead(potPedal);            
  sensorScaler = analogRead(potRange);
  int scalerValue = map(sensorScaler, 0, 1023, 0, 1002);  
  
  if(Direction)
    outputValue = map(sensorValue-sensorOffset, 0, 1023, -1*scalerValue, scalerValue);  
  else
    outputValue = map(sensorValue-sensorOffset, 0, 1023, scalerValue, -1*scalerValue);  
  if(outputValue <= -1000)
    outputValue = -1000;
  if(outputValue >= +1000)
    outputValue = 1000;
  if(outputValue >= -5 && outputValue <= 5)
    outputValue = 0;

  // ==========================   Command the Motor & Get back information by the Board
  if(Paused) {
    outputValue = 0;
    if(millis()-pauseBlink > 250) {
      if (pauseLedStatus == LOW)
        pauseLedStatus = HIGH;
      else
        pauseLedStatus = LOW;
      digitalWrite(ledPause, pauseLedStatus);
      pauseBlink = millis();
    }
  } else if(pauseLedStatus=HIGH) {
    pauseLedStatus = LOW;
    digitalWrite(ledPause, pauseLedStatus);
  }

  //===================================   Motor Control
  Serial1.print("!G 1 " );                       
  Serial1.println(outputValue);
  
  if(loopCnt++ % 20) {
    delay(10);
    
    // =================================   FeedBack from Roboteq Board
    
    Serial1.println("?V_?A_?C 1_?T_?FF_?FS\r" );
    unsigned long recTime = millis();
    while (Serial1.available() > 0  || millis()-recTime<50) {
      char inChar = (char)Serial1.read();     // get the new byte:
      inputString += inChar;
      if(inputString.indexOf("FS=")<inputString.lastIndexOf('\r'))
        stringComplete = true;
    }
    
    // =================================   Leds Management
    if(stringComplete) {
      //Serial.println(inputString);  // Print entire string from controller
      
      
      if(dispVoltage1 == 0.0 || abs(parseReceivedValue(inputString,"V=",":",":",10.0) - dispVoltage1) <= 10.0)
        dispVoltage1 = parseReceivedValue(inputString,"V=",":",":",10.0);
      //Serial.println(dispVoltage1);
         
      
      if(parseReceivedValue(inputString,"A=","=",":",10.0) != -1.0)
        dispMotAmps1 = parseReceivedValue(inputString,"A=","=",":",10.0);
      //Serial.println(dispMotAmps1);
      
      
      if(parseReceivedValue(inputString,"T=","=",":",1.0) != -1.0)
        dispTemp1 = parseReceivedValue(inputString,"T=","=",":",1.0);
      //Serial.println(dispTemp1);
      
         
       if(parseReceivedValue(inputString,"C=","=",":",1.0) != -1.0)
        dispCount1 = parseReceivedValue(inputString,"C=","=",":", 1.0);
       Serial.println(dispCount1);
      
  
      fFault = (int) parseReceivedValue(inputString,"FF=","=","\r",1.0);
      fStatus = (int) parseReceivedValue(inputString,"FS=","=","\r",1.0);
  /*
      if(fFault & maskEmerg)
        Emergency = true;
      else
        Emergency = false;
  */
      digitalWrite(ledSerialCom, (fStatus & maskSerial));
      digitalWrite(ledStall, (fStatus & maskStall));
      digitalWrite(ledLimitSwitch, (fStatus & maskLimit));
      
      //Serial.println(fStatus & maskSerial);
      
      digitalWrite(ledOverTemp, (fFault & maskOverT));
      digitalWrite(ledOverVolt, (fFault & maskOverV));
      digitalWrite(ledUnderVolt, (fFault & maskUnderV));
      digitalWrite(ledShort, (fFault & maskShort));
      digitalWrite(ledErgencyStop, (fFault & maskEmerg));
      
      inputString = "";
      stringComplete = false;
    }
    loopCnt=0;
  } 
  
  // wait 10 milliseconds before the next loop
  // for the analog-to-digital converter to settle
  // after the last reading:
  delay(10);   // Aqui estava 25ms


}

float parseReceivedValue(String input,String answerHeader, String startDelimiter, String endDelimiter, float divider) {
  float retValue;
  int startPos = input.indexOf(startDelimiter,input.indexOf(answerHeader)) + 1;
  int endPos=input.indexOf(endDelimiter,startPos);
  if(startPos==-1 || endPos==-1)
    retValue = -1.0;
  else
    retValue = StrToFloat(input.substring(startPos,endPos))/divider;
  return retValue;
}

float StrToFloat(String str){
  char carray[str.length() + 1];
  str.toCharArray(carray, sizeof(carray));
  return atof(carray);
}

float StrToInt(String str){
  char carray[str.length() + 1];
  str.toCharArray(carray, sizeof(carray));
  return atoi(carray);
}
9

Do you see "Led Check..." and "Display Check..." on the serial monitor?

10

Yes, I see all the "direct" prints, what I don't see are the elements from the motor telemetry that is parsed from the string

11

Are you getting a line feed when the println occurs, or not even that?

Edit:
It may be worth converting the float to a string to see if that fixes it