Freezing on function call

Forum 2005-2010 (read only) Software Syntax & Programs
#1 
#include <Ethernet.h>
#include <string.h>
#include <stdio.h>

unsigned int getTemp();
unsigned int getLight();
boolean sendUpdate();



#define TEMP 0 //Analog temperature sensor
#define LIGHT 1 //Analog Light sensor


boolean sendUpdate(){
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
byte ip[] = { 192, 168, 1, 117 };                      // this is the ip within my lan
byte gateway[] = { 192, 168, 1, 1 };                  // neccessary to get access to the internet via your router
byte subnet[] = { 255, 255, 255, 0 };
byte server[] = { 128, 121, 146, 100 };               // Twitter's ip
unsigned int temp=getTemp();
unsigned int light=getLight();
char tempinterest[]="";
char lightinterest[]="";
char msg[140] = "";
char stats[] = "status=";
char tempc[5];
itoa(temp, tempc, 10);

  

  if(temp > 100){
     strcpy(tempinterest,"So Hot I'm going to die");
  } else if(temp >= 95){
    strcpy(tempinterest,"Hot as hell");
  } else if(temp > 80){
    strcpy(tempinterest,"Hot");
  } else if(temp < 65){
    strcpy(tempinterest,"Cold");
  } else if(temp < 60){
    strcpy(tempinterest,"real cold");
  } else if(temp < 55){
    strcpy(tempinterest,"freezing");
  } else {
    strcpy(tempinterest,"Comfortable");
  }

  if(light > 70){
    strcpy(lightinterest,"bright");
  } else if(light < 40){
    strcpy(lightinterest,"dark");
  } else {
    strcpy(lightinterest,"not too dark");
  }

  strcat(msg, "It's ");
  strcat(msg, tempinterest);
  strcat(msg, " (");
  strcat(msg, tempc);
  strcat(msg, "F) and ");
  strcat(msg, lightinterest);
  strcat(msg, " in here");
  
  Serial.println(msg);

  Ethernet.begin(mac, ip, gateway, subnet);

  Client client(server, 80);
  Serial.println("connecting...");

  if (client.connect()) {
    Serial.println("connected");
    client.println("POST http://twitter.com/statuses/update.json HTTP/1.1");
    client.println("Host: twitter.com");
    client.println("Authorization: Basic ??????");   
                                                                        
    client.println("Content-type: application/x-www-form-urlencoded");
    client.println("Content-length: 139");                              
    client.println("Connection: Close");
    client.println();
    strcat(stats, msg);
    client.print(stats);

  } else {
    Serial.println("connection failed");
    return false;
  }
  

    client.stop();
    return true;   
}
unsigned int getTemp(){
  // @return degrees in F
  int tempc = 0,tempf=0; // temperature variables
  int samples[8]; // variables to make a better precision
for(int i = 0;i<=7;i++){ // gets 8 samples of temperature

samples[i] = ( 5.0 * analogRead(TEMP) * 100.0) / 1024.0;
tempc = tempc + samples[i];
delay(1000);

}
  tempc = tempc/8.0; // better precision
  tempf = (tempc * 9)/ 5 + 32; // converts to fahrenheit
  return tempc-5;
}
unsigned int getLight(){
  // @return light in %
  return (analogRead(LIGHT)/849.0)*100.0;
}
void setup(){
Serial.begin(9600); // start serial communication
}
void loop(){
  sendUpdate();
  delay(3600000); //wait an hour before next check
}

I have this code that monitors the temperature and ambient light and twitters it.
however, I can’t figure out why, but the function sendUpdate(); freezes immediately when its run.
the Arduino restarts in about a minute.

If theres something inherently wrong with my code it would be appreciated if you could point it out, i’m out of ideas. :’(

#2

I think this could be a RAM problem, if using a ATmega168.

You could concider storing the response string in PROGMEM.

#3

This...

char tempinterest[]="";

...allocates a buffer of one character (the null terminator). This...

strcpy(tempinterest,"So Hot I'm going to die");

...tries to store 23+1 characters in the buffer. This...

char lightinterest[]="";

...allocates a buffer of one character. This...

strcpy(lightinterest,"not too dark");

...tries to store 12+1 characters in the buffer. This...

char stats[] = "status=";

...allocates a buffer of 7+1 characters. This...

strcat(stats, msg);

...tries to append a large string to stats.

Your program is overrunning at least those three buffers. The buffers are on the stack. By overrunning the buffers, the stack is corrupted. When the function tries to return to the caller, the program "freezes" because the return address is not valid.

When dealing with strings in C, the buffers have to be big enough for the longest string that will ever be stored in the buffer (plus one for the terminator).

#4

It was a RAM problem, I tried it with my 328 and it runs fine. Thanks for the help.

#5