DUE: Problems with reading from Serial.

I have problems getting a code working on the DUE, that works on the UNO with no problems. The reason that I what to shift from UNO to DUE is to get more SRAM for a bitmap to be requested through a HTTP-request (through a 3G shield from Cooking-Hacks) and printed out of on a Thermal Printer (not part of the attached code).

However, when I run this code (build on a tutorial provided by Cooking-Hacks for the UNO), it does't return any values to data[]. I read that the DUE sometimes has problems with serial.available/serial.read and needs a firmware update. Is this also the case with the 3rd revision board I just bought?

Here is my code for reference:

// 
#include <string.h>
#define MAX_STRING_LEN  100

int8_t answer;
int onModulePin = 2, aux;
int data_size = 0;
int end_file = 0;
char *p, *i;
char *text;
char *filename;
char *date;
char *time2; 


char aux_str[50];

char data[400];
int http_x;
int http_status;   // 0: end, 1 waiting data with header, 2 waiting data without header, 3 timeout waiting data, 4 unknow response
int x = 0;
long previous;


//Write here you SIM data
const char pin_number[] = "1001";
const char apn[] = "internet";
const char user_name[] = "";
const char password[] = "";

//


char url[ ]="www.infraordinary.dk";
int port= 80;
char request[ ]="GET /display_vars.php?test HTTP/1.1\r\nHost: www.infraordinary.dk\r\nContent-Length: 0\r\n\r\n";



void setup(){

  pinMode(onModulePin, OUTPUT);
  Serial.begin(115200);

  Serial.println("Starting...");
  power_on();

  delay(3000);

  //sets the PIN code
  sprintf(aux_str, "AT+CPIN=%s", pin_number);
  sendATcommand(aux_str, "OK", 2000);

  delay(3000);

  while( (sendATcommand("AT+CREG?", "+CREG: 0,1", 500) ||
    sendATcommand("AT+CREG?", "+CREG: 0,5", 500)) == 0 );


  // sets APN, user name and password
  sprintf(aux_str, "AT+CGSOCKCONT=1,\"IP\",\"%s\"", apn);
  sendATcommand(aux_str, "OK", 2000);

  sprintf(aux_str, "AT+CSOCKAUTH=1,1,\"%s\",\"%s\"", user_name, password);
  sendATcommand(aux_str, "OK", 2000);



}
void loop(){

  // request the url
  sprintf(aux_str, "AT+CHTTPACT=\"%s\",%d", url, port);
  answer = sendATcommand(aux_str, "+CHTTPACT: REQUEST", 60000);

  // Sends the request
  Serial.println(request);
  // Sends <Ctrl+Z>
  Serial.write(0x1A);
  http_status = 1;

  while ((http_status == 1) || (http_status == 2))
  {
    answer = sendATcommand("", "+CHTTPACT: ", 60000);
    if (answer == 0)
    {
      http_status = 3;
    }
    else
    {
      // answer == 1
      while(Serial.available()==0);
      aux_str[0] = Serial.read();

      if ((aux_str[0] == 'D') && (http_status == 1))
      {
        // Data packet with header
        while(Serial.available()<4);
        Serial.read();  // A
        Serial.read();  // T
        Serial.read();  // A
        Serial.read();  // ,

        // Reads the packet size
        x=0;
        do{
          while(Serial.available()==0);
          aux_str[x] = Serial.read();
          x++;
        }
        while((aux_str[x-1] != '\r') && (aux_str[x-1] != '\n'));

        aux_str[x-1] = '\0';
        data_size = atoi(aux_str);

        // Now, search the end of the HTTP header (\r\n\r\n)
        do{
          while (Serial.available() < 3);

          data_size--;
          if (Serial.read() == '\r')
          {
            data_size--;
            if (Serial.read() == '\n')
            {
              data_size--;
              if (Serial.read() == '\r')
              {
                data_size--;
                if (Serial.read() == '\n')
                {
                  // End of the header found
                  http_status = 2;
                }
              }
            }   
          }
        }
        while ((http_status == 1) && (data_size > 0));

        if (http_status == 2)
        {
          // Reads the data
          http_x = 0;
          do{
            if(Serial.available() != 0){
              data[http_x] = Serial.read();
              http_x++;
              data_size--;
            }
            else
            {
              delay(1);
            }
          }
          while(data_size > 0);
          data[http_x] = '\0';
        }
      }
      else if ((aux_str[0] == 'D') && (http_status == 2))
      {
        // Data packet with header
        while(Serial.available()<4);
        Serial.read();  // A
        Serial.read();  // T
        Serial.read();  // A
        Serial.read();  // ,

        // Reads the packet size
        x=0;
        do{
          while(Serial.available()==0);
          aux_str[x] = Serial.read();
          x++;
        }
        while((aux_str[x-1] != '\r') && (aux_str[x-1] != '\n'));

        aux_str[x-1] = '\0';
        data_size = atoi(aux_str);

        do{
          if(Serial.available() != 0){
            data[http_x] = Serial.read();
            http_x++;
          }
          else
          {
            delay(1);
          }
        }
        while(data_size > 0);
        data[http_x] = '\0';

      }
      else if (aux_str[0] == '0')
      {
        // end of the AT command
        http_status = 0;
      }
      else
      {
        // unknow response
        http_status = 4;
        Serial.print(char(aux_str[0]));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
        Serial.print(char(Serial.read()));
      }         
    }      
  }

  if (http_status == 0)
  {
// Makes variables out of data[]:
    Serial.print(F("HTTP data: "));
    Serial.println(data);
  Serial.println("Split record1: ");
  filename = subStr(data, "=", 2);
  date = subStr(data, "=", 3);
  time2 = subStr(data, "=", 4);
  text = subStr(data, "=", 5);
  Serial.println(filename);
  Serial.println(date);
  Serial.println(time2);
  Serial.println(text);
    
  }
  else
  {
    Serial.print(F("http_status: "));
    Serial.println(http_status, DEC);
  }



  delay(1000);

}

void power_on(){

  uint8_t answer=0;

  // checks if the module is started
  answer = sendATcommand("AT", "OK", 2000);
  if (answer == 0)
  {
    // power on pulse
    digitalWrite(onModulePin,HIGH);
    delay(3000);
    digitalWrite(onModulePin,LOW);

    // waits for an answer from the module
    while(answer == 0){
      // Send AT every two seconds and wait for the answer
      answer = sendATcommand("AT", "OK", 2000);
    }
  }

}


int8_t sendATcommand(   char* ATcommand,
char* expected_answer1,
unsigned int timeout)
{

  return sendATcommand2(   ATcommand, 
  expected_answer1, 
  expected_answer1, 
  timeout);
}

int8_t sendATcommand2(   char* ATcommand,
char* expected_answer1,
char* expected_answer2,
unsigned int timeout)
{

  uint8_t x=0,  answer=0;
  char response[100];
  unsigned long previous;

  memset(response, '\0', 100);    // Initialize the string

  delay(100);

  while( Serial.available() > 0) Serial.read();    // Clean the input buffer

  Serial.println(ATcommand);    // Send the AT command


    x = 0;
  previous = millis();

  // this loop waits for the answer
  do{

    if(Serial.available() != 0){
      response[x] = Serial.read();
      x++;
      // check if the desired answer is in the response of the module
      if (strstr(response, expected_answer1) != NULL)
      {
        answer = 1;
      }
      // check if the desired answer is in the response of the module
      if (strstr(response, expected_answer2) != NULL)
      {
        answer = 2;
      }
    }
    // Waits for the asnwer with time out
  }
  while((answer == 0) && ((millis() - previous) < timeout));

  return answer;
} 

// Function to return a substring defined by a delimiter at an index
  char* subStr (char* str, char *delim, int index) {
  char *act, *sub, *ptr;
  static char copy[MAX_STRING_LEN];
  int i;

  // Since strtok consumes the first arg, make a copy
  strcpy(copy, str);

  for (i = 1, act = copy; i <= index; i++, act = NULL) {
     //Serial.print(".");
     sub = strtok_r(act, delim, &ptr);
     if (sub == "=") break;
  }
  return sub;

}

Thanks a lot in advance!

HTTP_Terminal_get_var_DUE.ino (7.3 KB)

By the way: at the Uno I had to increase the Buffer to 400. I also tried to increase RingBuffer to 400 on the DUE, however, that didn't work either.

If anyone knows something about this I would be very grateful...

Arduiono code works with latest version of IDE v1.0.6 and greater. Lower version of arduino IDE wont support Due Board

Thanks for your reply, AMPS-N.

I work with IDE v.1.5.4 (with RingBuffer set to 400) and IDE v.1.6.1. None of them works with this particular code, but other codes that do not include serial.available and serial.read works perfectly.