8x8 DOT MATRIX_o/p is flip scrolling and brightness issues.......

[dattlara76]

HI ALL,
I am trying to convert the code written for avr into XC8 16F877A(https://circuitdigest.com/microcontroller-projects/8x8-led-matrix-with-avr-atmega8)
and the modified code.
The ckt diagram and dot matrix with internal pin configuration(from datasheet) what I am using is also been attached.
>>>>But why not getting EXPECTED O/P in the display? Only getting invert character.
I have tested LEFT-UPPER-MOST-CORNER LED to check the position for placement of the module and the same LED is glow when pin (9) -> is given GND and pin (13) -> is provided VCC.
The module has been placed as per image shown here.
>>>>And another issue that, along with inverse character some LEDs glowing brightly and some dimmed?
What i am doing wrong for both cases.

Thnk in advance..

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// CONFIG
#pragma config FOSC = HS        // Oscillator Selection bits (HS oscillator)
#pragma config WDTE = OFF       // Watchdog Timer Enable bit (WDT disabled)
#pragma config PWRTE = ON       // Power-up Timer Enable bit (PWRT enabled)
#pragma config BOREN = ON       // Brown-out Reset Enable bit (BOR enabled)
#pragma config LVP = OFF        // Low-Voltage (Single-Supply) In-Circuit Serial Programming Enable bit (RB3 is digital I/O, HV on MCLR must be used for programming)
#pragma config CPD = OFF        // Data EEPROM Memory Code Protection bit (Data EEPROM code protection off)
#pragma config WRT = OFF        // Flash Program Memory Write Enable bits (Write protection off; all program memory may be written to by EECON control)
#pragma config CP = OFF         // Flash Program Memory Code Protection bit (Code protection off)
 
// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.
 
#include <xc.h>
#include <stdint.h>         // include stdint header
 
/* To display a still letter 'F' in the display */
 
#define _XTAL_FREQ 20000000
 
//static int ALPHA[26][8]= {
const char ALPHA [26][8] = {    
    {0,0b01111111,0b11111111,0b11001100,0b11001100,0b11001100,0b11111111,0b01111111},           //A//1
 
    {0,0b00111100,0b01111110,0b11011011,0b11011011,0b11011011,0b11111111,0b11111111},            //B//2
 
    {0,0b11000011,0b11000011,0b11000011,0b11000011,0b11100111,0b01111110,0b00111100},            //C//3
 
    {0,0b01111110,0b10111101,0b11000011,0b11000011,0b11000011,0b11111111,0b11111111},            //D//4
 
    {0,0b11011011,0b11011011,0b11011011,0b11011011,0b11011011,0b11111111,0b11111111},            //E//5
 
    {0,0b11011000,0b11011000,0b11011000,0b11011000,0b11011000,0b11111111,0b11111111},            //F//6
 
    {0b00011111,0b11011111,0b11011000,0b11011011,0b11011011,0b11011011,0b11111111,0b11111111},   //G//7
 
    {0,0b11111111,0b11111111,0b00011000,0b00011000,0b00011000,0b11111111,0b11111111},             //H//8
 
    {0b11000011,0b11000011,0b11000011,0b11111111,0b11111111,0b11000011,0b11000011,0b11000011},    //I//9
 
    {0b11000000,0b11000000,0b11000000,0b11111111,0b11111111,0b11000011,0b11001111,0b11001111},     //J//10
 
    {0,0b11000011,0b11100111,0b01111110,0b00111100,0b00011000,0b11111111,0b11111111},               //K//11
 
    {0b00000011,0b00000011,0b00000011,0b00000011,0b00000011,0b00000011,0b11111111,0b11111111},      //L//12
 
    {0b11111111,0b11111111,0b01100000,0b01110000,0b01110000,0b01100000,0b11111111,0b11111111},      //M//13
 
    {0b11111111,0b11111111,0b00011100,0b00111000,0b01110000,0b11100000,0b11111111,0b11111111},       //N//14
 
    {0b01111110,0b11111111,0b11000011,0b11000011,0b11000011,0b11000011,0b11111111,0b01111110},       //O//15
 
    {0,0b01110000,0b11111000,0b11001100,0b11001100,0b11001100,0b11111111,0b11111111},                 //P//16
 
    {0b01111110,0b11111111,0b11001111,0b11011111,0b11011011,0b11000011,0b11111111,0b01111110},         //Q//17
 
    {0b01111001,0b11111011,0b11011111,0b11011110,0b11011100,0b11011000,0b11111111,0b11111111},         //R//18
 
    {0b11001110,0b11011111,0b11011011,0b11011011,0b11011011,0b11011011,0b11111011,0b01110011},          //S//19
 
    {0b11000000,0b11000000,0b11000000,0b11111111,0b11111111,0b11000000,0b11000000,0b11000000},              //T//20
 
    {0b11111110,0b11111111,0b00000011,0b00000011,0b00000011,0b00000011,0b11111111,0b11111110},              //U//21
 
    {0b11100000,0b11111100,0b00011110,0b00000011,0b00000011,0b00011110,0b11111100,0b11100000},              //V//22
 
    {0b11111110,0b11111111,0b00000011,0b11111111,0b11111111,0b00000011,0b11111111,0b11111110},              //W//23
 
    {0b01000010,0b11100111,0b01111110,0b00111100,0b00111100,0b01111110,0b11100111,0b01000010},              //X//24
 
    {0b01000000,0b11100000,0b01110000,0b00111111,0b00111111,0b01110000,0b11100000,0b01000000},              //Y//25
 
    {0b11000011,0b11100011,0b11110011,0b11111011,0b11011111,0b11001111,0b11000111,0b11000011}               //Z//26
    
    };//characters a,b,c,d,e,f,g,...z binary codecs
 
 
int main(void)
{
 
    TRISB = 0x00;//PORTB,C,D are set as output
    TRISC = 0x00;
    TRISD = 0x00;
    
    //PORT[8] = {1,2,4,8,16,32,64,128};//pin values of PORTD
    int VAL[8] = {1,2,4,8,16,32,64,128};//pin values of PORTD
                                            
 
    char NAME[]={2,8,17,2,20,8,19,3,8,6,4,18,19};///circuitdigest character values
    uint8_t l =0;
    while(1)
        {
            for (int m=0;m<sizeof NAME;m++)
                {
                    l = NAME[m];
                    for (int n=0;n<200;n++)//execute 200 times for the eye to catch
                        {
                                for (int j=0;j<4;j++)
 
                                {
                                                PORTB = ~VAL[j];// ROW
                                                PORTD = ALPHA[l][j];//show half of character (COLUMN)
                                                __delay_us(500);
 
                                }
 
                                PORTB=0xFF;//clear screen after show
 
                                for (int k=0;k<4;k++)
 
                                {
                                                PORTC = ~VAL[k];// ROW
                                                PORTD = ALPHA[l][k+4];//show other half of character(COLUMN)
                                                __delay_us(500);
 
                                }
 
                                PORTC=0xFF;//clear screen after show.
 
                        }
 
                }
 
                __delay_ms(220);
 
                __delay_ms(220);
 
                __delay_ms(220);
 
                __delay_ms(220);
 
                __delay_ms(220);
 
        }
 
}

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[betwixt]

Take a closer look at the original schematic - you are missing some resistors.

Brian.

 

[andre_luis]

First of all, you are not using any current limiting resistors in the microcontroller outputs, and according to the datasheet, a maximum current is not defined, but a typical range. Furthermore, what do you mean by inverted character? Orientation? Inverted 'colors' (dark/light)?

 

[dattlara76]

hi,
sorry to say that the, Limit resistor R330 of 8 nos had inclUded at RD0 to RD7 PIN of MCU and same connected with DOT module pin from (1) to pin (7) bur here in sche. forgot to mention/show.
If = 20mA(max),
Vr = 5v(min).

I mean displaying each character in Oriented manner and brightness of some of them which is glowing (under oriented) is less compared to others under glowing under the same character..
tnx.

 

[betwixt]

I appreciate it isn't easy to photograph a dynamic display but it would help if we could see the problem. Note that the maximum current available from any PIC pin is 20mA and there is also a limit for the port as a whole, you might be exceeding it.

Brian.

 

[dattlara76]

Hi,
Is the code and pin connection in correct way.
Is the array "ALPHA[]" for particular alphabets are according to my ckt connection.

"C" is displaying as "U"
pl suggest
tnx

 

[KlausST]

Hi,

Is the array "ALPHA[]" for particular alphabets are according to my ckt connection.

"C" is displaying as "U"

My recommendation (this is how we need to check it, too):
Take a sheet of checkered paper and do the paintwork yourself:
For every byte take 8 boxes in a row..
For every "1" fill the box with dark color, for every "0" leave the box blank.

Klaus

 

[andre_luis]

"C" is displaying as "U"

Surely the following routine will be useful to you, obviously with the appropriate modifications. In the case, I used it just to remap the character's fonts, and with the output of the execution, I replaced the original map.

https://www.edaboard.com/blog/1913

BTW, considering that the display has a clear symmetry in rows/colums, why not just physicaly turning the display itself by 90 degrees?