PIC16F877A freezes after a certain event

abicash · Oct 26, 2017

Hello forum

My setup:
I am using a 16f877a with 11.0592MHz crytal and MPLAB IDE ver 8.92
Programmer is PICkit3.
Configuration :
HS OSC , WDT-disabled , PWRT-disabled, BOR-disabled,RB3-dig i/o,&MCLR pulled up to VCC=5v
All memory protections are off

I am driving 8 nos of 7 segment displays and 4 keys as input (all keys individual and not in a 2x2 matrix)

I am using a couple of unsigned long variables and no re-entrants in ISR's.
I also have an LED toggling in a one second TMR0 interrupt to show that the MCU is alive.

I am trying to display an 8-digit BCD number on the display on few key-presses.
Simulation works fine in proteus.

Display shows 0 0 0 0 0 0 0 0 - on reset
Press SET key
Display shows S E t
Press ENTER key
Display shows 1 2 3 4 5 6 7 8 (converted from decimal 12345678 or 0xBC614E)

On actual hardware
Display shows 0 0 0 0 0 0 0 0 - on reset
Press SET key
Display shows S E t
Press ENTER key
Display turns blank
MCU freezes
One second tick LED stops ticking.

I thought that this might be related to stack overflow , but I don't have re-entrant levels in ISR as I mentioned earlier.

I am now unable to understand this phenomenon, so requesting some learned members help on this one.

Thanks in advance

Pommie · Oct 26, 2017

You have code that doesn't work and you want to know why but you don't include the code.

We're not mind readers.

Mike.

abicash · Oct 26, 2017

Thanks for replying.
I am attaching the code , but its a bit messy since yesterday , lots of commented lines.
Please bear with me

C:

#include <pic.h>
#include "stdio.h"

const unsigned char SET_KEY_PRESSED = 0x30;
const unsigned char UP_KEY_PRESSED = 0x24;
const unsigned char ENTER_KEY_PRESSED = 0x14;

const unsigned char seg_sel[8]={0x01,0x02,0x04,0x08,0x10,0x20,0x40,0x80};
const unsigned char seg[15]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90,0x77,0x7C,0x39,0x5E,0x71};
const unsigned char set[8]  ={0xFF,0xFF,0xFF,0xFF,0xFF,0x92,0x86,0x87};
const unsigned char rst[8]  ={0xFF,0xFF,0xFF,0xFF,0xFF,0xAF,0x92,0x87};
const unsigned char out[8]  ={0xFF,0xFF,0xFF,0xFF,0xFF,0xC0,0xC1,0x87};
const unsigned char yes[8] = {0xFF,0xFF,0xFF,0xFF,0xFF,0x91,0x86,0x92};
const unsigned char Noo[8] = {0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xAB,0xC0};
const unsigned char test[8] = {0xFF,0xFF,0x92,0x86,0x87,0xFF,0xAB,0xC0};

unsigned int count=0;
unsigned char seg_counter;
unsigned char val[10];
unsigned char Key_Scan_Value=0,Key_Value=0;
unsigned char Key_Pressed=0;
unsigned int set_delay,delay_count=0,start_delay=0;
unsigned char Chk_All_Key_Open=0;
unsigned char Start_Set_Timer=0,Setting_mode=0;
unsigned int Set_Timer_Count=0,Set_timer_complete=0;
unsigned char display_string=0;
unsigned char Setting_Case=0;
unsigned char position_couter=0;
unsigned int Start_Blinking=0,Blink_Count=0,Blink_Value=0;
unsigned char Disp_Position=0;
unsigned long Set_Count_Value=0;
unsigned char temp1=0,temp2=0,temp3=0,temp4=0;

 signed char index=0 ;

void delayms(unsigned int count);
unsigned char Check_Key_Pressed(void);

void timer0_init(void)
{
    OPTION = 0x83;//option reg as 0x83
    TMR0 = 83;
    T0IE = 1;//timer 0 interrupt enable flag
    GIE = 1;
}


//--------------------------------------------------------------------------------------------------------
void timer1_init(void)
{
    T1CON = 0x01;
    TMR1H = 0xF5;
    TMR1L = 0x33;
    TMR1IE = 1;
}
//--------------------------------------------------------------------------------------------------------
void delayms(unsigned int count)
{
     delay_count = 0;
     set_delay = count;
      start_delay = 1;
      while(start_delay == 1);
}
//---------------------------------------------------------------------------------------------------------

//--------------------------------------------------------------------------------------------------------
void display_number_upto_99(unsigned char value)
{
    unsigned char k;
    k = value;
    val[0] = k/10;
    k = k%10;
    val[1] = k;
}
//--------------------------------------------------------------------------------------------------------
void display_set_on_display()
{
    unsigned char i;
    display_string = 1;
    for(i=8;i>0;i--)
    val[i-1] = set[8-i];
}
//--------------------------------------------------------------------------------------------------------
void display_test_on_display()
{
    unsigned char i;
    display_string = 1;
    for(i=8;i>0;i--)
    val[i-1] = test[8-i];
}
//--------------------------------------------------------------------------------------------------------
void display_rst_on_display()
{
    unsigned char i;
    display_string = 1;
    for(i=8;i>0;i--)
    val[i-1] = rst[8-i];
}
//--------------------------------------------------------------------------------------------------------
void display_out_on_display()
{
    unsigned char i;
    display_string = 1;
    for(i=8;i>0;i--)
    val[i-1] = out[8-i];
}
//--------------------------------------------------------------------------------------------------------------------------
void interrupt any_ISR(void)
{
//--------------------------------------------------------------------------------------------------------
    if (T0IF==1)
    {
        seg_counter++;
        if(seg_counter > 7)
            seg_counter = 0;
        PORTD = 0x00;
        PORTD = seg_sel[seg_counter];
        PORTB = 0xFF;
        if(display_string == 0)
        {
                        PORTB = seg[val[seg_counter]];
        }
        else
            PORTB = val[seg_counter];
    
        T0IF=0;
        TMR0 = 83;
    }
//--------------------------------------------------------------------------------------------------------
    if(TMR1IF)
    {
        count++;
        if(count > 1000)
        {
            count = 0;
            RC3 ^=1;
        }
        if(Start_Set_Timer==1)
        {
            Set_Timer_Count++;
        if(Set_Timer_Count > 1000)
            {
                Set_Timer_Count = 0;
                Start_Set_Timer = 0;
                Set_timer_complete = 1;
            }
        }
    
        if(start_delay == 1)
            delay_count++;
        if(delay_count > set_delay)
        {
               set_delay = 0;
               start_delay = 0;
        }

        TMR1IF = 0;
        TMR1H = 0xF5;
        TMR1L = 0x33;
    }
}
//--------------------------------------------------------------------------------------------------------
void soft_delay(void)
{
    unsigned int i;
    for(i=0;i<1000;i++);
}
//-------------------------------------------------------------------------------------------------------------------------
unsigned char Check_Key_Pressed(void)
{
        Set_Timer_Count = 0;
        Start_Set_Timer = 0;
        Key_Value = 0;
        Key_Scan_Value = 0;
        Key_Scan_Value = PORTA & 0x34;
        if(Key_Scan_Value != 0x34)
            {
                Key_Scan_Value = PORTA & 0x34;
                RC4 = 1;
                soft_delay();//soft_delay();soft_delay();
                RC4 = 0;
                Key_Scan_Value = PORTA & 0x34;
                if(Key_Scan_Value != 0x34)
                {
                    Chk_All_Key_Open = 1;
                    Key_Value  = Key_Scan_Value;
                }
            }
    if(Chk_All_Key_Open == 1)
    {
        do
        {
            Key_Scan_Value = PORTA & 0x34;
        }while(Key_Scan_Value != 0x34);
        Chk_All_Key_Open = 0;
    }
        return(Key_Value);
}
//--------------------------------------------------------------------------------------------------------

//-----------------------------------------------------------------------------------------
void main(void)
{
    unsigned long temp_i=0;
    unsigned char k=0;
  
    TRISC = 0x00;
    TRISD = 0x00;
    TRISB = 0x00;
    timer0_init();
    timer1_init();
    ADCON1 = 0x04;
    TRISA = 0x3F;
    
    delayms(250);

    display_string = 0;
    Setting_Case = 0;
    position_couter = 0;
//-----------------------------------------------------------------------------------------------------

    while(1)
    {
            Key_Pressed = Check_Key_Pressed();
            if((Key_Pressed == SET_KEY_PRESSED) && (Setting_mode ==0))
            {
                Key_Pressed = 0;
                    Setting_mode = 1;
                display_set_on_display();
            }

          if(Setting_mode == 1)
            {
                switch(Setting_Case)
                {
                    case 0:
                                
                                    if(Key_Pressed == UP_KEY_PRESSED)
                                        {
                                            Key_Pressed = 0;
                                            position_couter++;
                                            if(position_couter > 2)
                                                position_couter = 0;
                                    
                                            if(position_couter == 0)
                                                             display_set_on_display();
                                             else if(position_couter == 1)
                                                            display_rst_on_display();
                                            else if(position_couter == 2)
                                                            display_out_on_display();
                                         }
                                        if(Key_Pressed == ENTER_KEY_PRESSED)
                                        {
                                            Key_Pressed = 0;
                                               if(position_couter == 0)
                                               {
                                                   Setting_Case = 1;
                                                   Blink_Value = 0;
                                                   Blink_Count = 0;
                                                   Start_Blinking = 1;
                                                }
                                        }
                                    k=0;
                            break;

                    case 1:        
                               display_string = 0;
                                if(k==0)
                                {
                                       k=1;
                                      Set_Count_Value = 12345678;
                                      for ( index=0; Set_Count_Value>0; index++  )
                                       {
                                            temp_i = Set_Count_Value / 10 ;
                                            val[index] = Set_Count_Value-10*temp_i ;
                                            Set_Count_Value = temp_i ;
                                        }
                                 }
                        
                            break;
                }
            }
                     Key_Pressed = 0;
    }//while(1)
}//main()

Pommie · Oct 27, 2017

Can I suggest that the first thing you do is to go through your code and properly indent it as some of it makes no sense such as this opening brace,

Code:

    case 1:
        display_string = 0;
            if(k==0){
                k=1;
                //if(Start_Blinking == 0)
                Set_Count_Value = 12345678;
                {                    <-------------This one
                for ( index=0; Set_Count_Value>0; index++  )
                {
                    temp_i = Set_Count_Value / 10 ;
                    val[index] = Set_Count_Value-10*temp_i ;
                    Set_Count_Value = temp_i ;
                }
                //Start_Blinking = 1;
            }//display_test_on_display();

Mike.
Edit, did you think this line was remarked out?
/**/ for ( index=0; Set_Count_Value>0; index++ )

abicash · Oct 27, 2017

Mike

I have edited the code for indents and other parses

EDIT : I have been debugging the code with a Pickit3 for some time now.

And i have found that the debugger shows the variable <temp_i> as <out of scope> after one pass through the <for ( index=9; Set_Count_Value>0; index-- )> loop.

Is this of some relevance?

Pommie · Oct 27, 2017

abicash said:
Mike

I have edited the code for indents and other parses

EDIT : I have been debugging the code with a Pickit3 for some time now.

And i have found that the debugger shows the variable <temp_i> as <out of scope> after one pass through the <for ( index=9; Set_Count_Value>0; index-- )> loop.

Is this of some relevance?

The indenting above is still all wrong and I can't even find that (for) line in your code.

Mike.

abicash · Oct 27, 2017

abicash said:
And i have found that the debugger shows the variable <temp_i> as <out of scope> after one pass through the <for ( index=9; Set_Count_Value>0; index-- )> loop.

I am extremely sorry for the wrong message above.
Actually it should be

Code:

for ( index=0; Set_Count_Value>0; index++  )

I checked the indents for braces again, and i think they are in line (opening and closing braces)
can you kindly point out the area , which i will correct.

UPDATE : I have been able to move a bit ahead

In the timer ISR, this part is a bit doubtful

Code:

    if(display_string == 0)
        {
                        PORTB = seg[val[seg_counter]];
        }
        else
            PORTB = val[seg_counter];

If I do not check the "display_string" and directly pass value to PORTB, all's good.

abicash · Oct 29, 2017

All problems were resolved after using MPLAB-X IDE

atferrari · Nov 1, 2017

abicash said:
All problems were resolved after using MPLAB-X IDE

Maybe I got it wrong but, have you solved a hardware problem using a different IDE?

PIC16F877A freezes after a certain event

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