Software Serial.available breaking hardware Serial.available

Projects Programming
1

Hi.

I'm having a strange problem. It seems as if the software serial.available is breaking the hardware serial.available. After a few commenting-outs, I've isolated the part of sendData() that's causing the problem, being the sendATcommand function (hint: it uses softwareserial.available!)

Code:

#include <LCD5110_Graph.h>
LCD5110 myGLCD(6,8,9,10,11);
extern uint8_t SmallFont[];

#include <SoftwareSerial.h>
SoftwareSerial GPRS(2, 3);


void setup(){
  pinMode(13,OUTPUT);
  myGLCD.InitLCD();
  myGLCD.setFont(SmallFont);
  GPRS.begin(4800);  
  Serial.begin(9600);
  sendData(); 
}
  
  int a=0;
  char item [300];
void loop(){ 
  //uncommenting this code breaks the sendData function!
//  while(Serial.available()>0){
//  item[a] = Serial.read();
//  a++;
//  if(a==250){
//    a=0; //reset array
//    //traverse through list to R
//    for(int i=0;i<250;++i){
//      if(item[i]=='R'){
//          show(String(item[i+1]));
//        }
//      }  
//    }
//  }
}

And the offending function within the sendData:

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

    uint8_t x=0,  answer=0;
    char response[500];
    unsigned long previous;

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

    delay(100);

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

    // Send the AT command 
   // Serial.print("Sending: ");
   // Serial.println(ATcommand);
    GPRS.println(ATcommand);
   // Serial.println(" (Sent) ");

        x = 0;
    previous = millis();

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

    return answer;
}

If sendData is commented out, the stuff in "loop" works fine. If the stuff in loop is commented out, sendData works fine.

Thanks in advance.

2

After some more isolation, it crashes at this line (within sendATcommand):

while( GPRS.available() > 0) GPRS.read();    // Clean the input buffer
3

Perhaps that while loops forever. Add a timeout?

4

I don't think so - I've put an LED in to blink after the while loop and it blinks fine...

5

Solved!

Change the length of the response array down to 250.

I have no clue why this works - anyone have any ideas?

6

You were short of memory ? The item array was already using 300 bytes even before you squandered 500 more for the response array. What board are you using ?

7

Good ol' Uno. The sketch size is 12000 bytes, but I guess at it runs the sketch things fill up?

8

Sketch is in 32k flash, but there's only 2k RAM...