Assigning values to char array causes program to not run

Question

I have the following code:

#include "LCD12864RSPI.h"
#include "DFrobot_bmp.h"
#include "DFrobot_char.h"
#define AR_SIZE( a ) sizeof( a ) / sizeof( a[0] )
unsigned char wangzhi[]=" www.DFRobot.com ";
unsigned char fused[1024];
void setup()
{
 pinMode(11, OUTPUT); 
 for(int i=0;i<4;i++){
 digitalWrite(11,HIGH);
 delay(1000);
 digitalWrite(11,LOW);
 delay(1000);
 }
 LCDA.initDriverPin(2,7,10); 
 LCDA.Initialise(); // INIT SCREEN 
}
unsigned char* fuse3(unsigned char* a ,unsigned char* b,unsigned char* c){
 int i=0;
 int ac=0;//a counter 
 int bc=0; //b counter 
 int cc=0;//c counter 
 for(int n=0;n<64;n++){
 for(int k=0;k<5;k++){
 fused[i]=a[ac];
 ac++;
 i++;
 }
 for(int k=0;k<5;k++){
 fused[i]=b[bc];
 bc++;
 i++;
 }
 for(int k=0;k<5;k++){
 fused[i]=c[cc];
 cc++;
 i++;
 }
 fused[i]=0x00;
 i++;
 }
 
 return fused;
}
unsigned char* getMatch(int input){
 input = input & 0x000f;
 switch (input){
 case 0: return g0;
 case 1: return g1;
 case 2: return g2;
 case 3: return g3;
 case 4: return g4;
 case 5: return g5;
 case 6: return g6;
 case 7: return g7;
 case 8: return g8;
 case 9: return g9;
 case 10: return plus;
 case 11: return minus;
 case 12: return times;
 case 13: return g1;
 case 14: return g1;
 case 15: return g1;
 default: return g1;
 }
 
}
void displayfuse(int number){
// LCDA.DrawFullScreen(fuse3(getMatch(1),getMatch(2),getMatch(3)));
}
void loop(){
 displayfuse(0x1234);
}

This code is a stripped version of the code I need to run to get a bigger project working. But if it somewhat works than the setup should begin by flashing a LED 4 times before continuing. Currently this works. However as you can see I have commented out the line LCDA.DrawFullScreen(fuse3(getMatch(1),getMatch(2),getMatch(3)));. uncommenting this line causes the LED's to flash continuously rather then just 4 times. The library I'm using can be found here. Does anybody know what is going on? To me the first few lines of a program can be affected by a change somewhere this deep inside the code is a form of dark magic.

Weirdly when I change the setup to the following: void setup()

{
 pinMode(11, OUTPUT); 
 for(int i=0;i<15;i++){
 digitalWrite(11,HIGH);
 delay(100);
 digitalWrite(11,LOW);
 delay(100);
 }
 for(int i=0;i<4;i++){
 digitalWrite(11,HIGH);
 delay(1000);
 digitalWrite(11,LOW);
 delay(1000);
 }
 LCDA.initDriverPin(2,7,10); 
 LCDA.Initialise(); // INIT SCREEN 
}

it stops flashing completely.

Edit having just reuploaded the code again this time the led just remains on all the time.

edit edit Now with the following code:

#include "LCD12864RSPI.h"
#include "DFrobot_bmp.h"
#include "DFrobot_char.h"
unsigned char fuse[1024];
void setup()
{
 LCDA.initDriverPin(2,7,10); 
 LCDA.Initialise(); // INIT SCREEN 
 pinMode(11, OUTPUT); 
 digitalWrite(11,HIGH); 
 
}
unsigned char* fuse3(unsigned char* a ,unsigned char* b,unsigned char* c){
 unsigned char* fused =(unsigned char*)malloc(sizeof(char)*1024);
 int i=0;
 int ac=0;//a counter 
 int bc=0; //b counter 
 int cc=0;//c counter 
 for(int n=0;n<64;n++){
 for(int k=0;k<5;k++){
 fused[i]=a[ac];
 ac++;
 i++;
 }
 for(int k=0;k<5;k++){
 fused[i]=b[bc];
 bc++;
 i++;
 }
 for(int k=0;k<5;k++){
 fused[i]=c[cc];
 cc++;
 i++;
 }
 fused[i]=0x00;
 i++;
 }
 return fused;
}
unsigned char* getMatch(int input){
 input = input & 0x000f;
 switch (input){
 case 0: return g0;
 case 1: return g1;
 case 2: return g2;
 case 3: return g3;
 case 4: return g4;
 case 5: return g5;
 case 6: return g6;
 case 7: return g7;
 case 8: return g8;
 case 9: return g9;
 case 10: return plus;
 case 11: return minus;
 case 12: return times;
 case 13: return g1;
 case 14: return g1;
 case 15: return g1;
 default: return g1;
 }
}
void displayfuse(int number){
 LCDA.CLEAR();
 delay(100);
 
 int mask1 = 0xF000;
 int mask2 = 0x0F00;
 int mask3 = 0x00F0;
 int firstnumber = number&mask1>>12;
 int operation = number&mask2>>8;
 int secondnumber= number&mask3>>4;
 
 LCDA.DrawFullScreen(fuse3(getMatch(firstnumber),getMatch(operation),getMatch(secondnumber)));
 delay(5000);
}
void loop(){
 displayfuse(0x1234);
 delay(1000)
}

This causes the led to not turn on but moving the lines where I make pin 11 output and high one up (beyond the LCDA.Initialise(); // INIT SCREEN ) then the led will turn on. It can also be turned on by commenting out the LCDA.DrawFullScreen(fuse3(getMatch(firstnumber),getMatch(operation),getMatch(secondnumber))); line. Magic is happening...

• Ignacio Vazquez-Abrams: Short answer: You're out of SRAM.
• Thijser: Memory usage is at around 6 kB leaving quite a bit around.
• Ignacio Vazquez-Abrams: Are you running this on a Mega?
• Thijser: This is on the "funduino" clone but I have 32 kB avaible and 6 in use.
• Ignacio Vazquez-Abrams: Is it the Funduino Mega2560?

Answer 1

The 'dark magic' is going to be your program rebooting every time it gets to that line. I would imagine (this isn't a library I know) that you're exceeding an array bound & generating a 'segfault', although it could be that you light up your LCD array & the power draw causes a reboot.. Because the LED flash is at the start of setup, it executes quickly, so generating the appearance of continual flashing when it re-enters repeatedly. Your code is going to assign g1[0] when the line in question executes - is g1[] defined to point somewhere valid?

• Thijser: Sounds plausible is there a good way of discovering if a segfault occurred? Normally I would use valgrind but what is the arduino option to check for this?
• Mark Williams: Headwork ;) Where is the code going when this line executes - see edit.
• Thijser: I'm not sure about it anymore I added in a second flash pattern (flash fast-flash slow) and now it doesn't even begin to flash anymore.
• Thijser: Oh and g[] is defined in a header file as a 320 chars array.
• Mark Williams: What about g1[]?