PIC16F877A LED lights PWM effect Question

[thilan d]

Hi friends...

am trying to do some PWM effected LED setup with portc and tmr0.. but i can only light up 3 leds each time
can some one help me to light up other leds that connected to port c please

thx a lot


""

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Code C - [expand]
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#include <htc.h>
#include <stdlib.h>
#include <pic.h>
#define _XTAL_FREQ 40000000
 
 
#define BLUE      RC0
#define RED       RC7
#define GREEN     RC5
#define BROWN     RC3
#define BLACK     RC4
#define YELLOW    RC2
#define ORANGE    RC6
#define ASH       RC1
 
 
#define ON              1
#define OFF             0
 
 
unsigned char pwmCounter = 0;
unsigned char redActual, redTarget, greenActual, greenTarget, blueActual, blueTarget; 
unsigned char brownActual, brownTarget, blackActual, blackTarget, yellowActual, yellowTarget;
unsigned char orangeActual, orangeTarget, ashActual, ashTarget;
 
unsigned char fade = 0;
 
void main(void) {
    TRISC   = 0;
    PORTC   = 0;
    T0CS    = 0;        // Internal Mode (Fosc/4)
    PSA     = 0;        // Prescaler assigned to TMR0
    PS2     = 1;
    PS1     = 0;
    PS0     = 0;        // Prescaler ratio 1:32
    T0IE    = 1;        // TMR0 overflow int. enable
    GIE     = 1;        // Global int. enable
    TMR0    = 131;      // (256-125=131) for 4mS time
 
 
//Set up initial LEDs off
redActual = 0;
greenActual = 0;
blueActual = 0;
brownActual = 0;
blackActual =0;
yellowActual = 0;
orangeActual =0;
ashActual = 0;
redTarget = 0;
greenTarget = 0;
blueTarget = 0;
brownTarget = 0;
blackTarget = 0;
yellowTarget = 0;
orangeTarget = 0;
ashTarget = 0;
 
        while (1) {
                redTarget       =   rand() % 60;
                greenTarget     =   rand() % 60;
                blueTarget      =   rand() % 60;
                brownTarget     =   rand() % 60;
                blackTarget     =   rand() % 60;
                yellowTarget    =   rand() % 60;
                orangeTarget    =   rand() % 60;
                ashTarget       =   rand() % 60;
 
                
//Can't do delay higher than 99ms, so chain multiple together
                for (int delay=0;delay<100;delay++) {
                        __delay_ms(10);
                }
        }
}
 
void interrupt timer0(void) {
        if (T0IF == 1) {
                fade++;
                
                if (fade == 64) {
                        if (redTarget > redActual)
                                redActual++;
                        else if (redTarget < redActual)
                                redActual--;
 
                        if (greenTarget > greenActual)
                                greenActual++;
                        else if (greenTarget < greenActual)
                                greenActual--;
 
                        if (blueTarget > blueActual)
                                blueActual++;
                        else if (blueTarget < blueActual)
                               blueActual--;
 
                        if (brownActual > brownActual)
                                brownActual ++;
                        else if (brownActual < brownActual)
                                brownActual --;
 
                        if (blackActual > blackActual)
                                blackActual ++;
                        else if (blackActual < blackActual)
                                blackActual --;
 
                        if (yellowActual > yellowActual)
                                yellowActual ++;
                        else if (yellowActual < yellowActual)
                                yellowActual --;
 
                        if (orangeActual > orangeActual)
                                orangeActual ++;
 
                        else if (orangeActual < orangeActual)
                                orangeActual --;
 
                        if (ashActual > ashActual)
                                ashActual ++;
                        else if (ashActual < ashActual)
                                ashActual --;
 
 
 
                }
 
               if (redActual > pwmCounter) {
                        RED = ON;
                        } else {
                        RED = OFF;
               }
 
               if (greenActual > pwmCounter) {
                        GREEN = ON;
                        } else {
                       GREEN = OFF;
                }
 
               if (blueActual > pwmCounter) {
                        BLUE = ON;
                        } else {
                      BLUE = OFF;
                }
                if (brownActual > pwmCounter) {
                        BROWN = ON;
                        } else {
                        BROWN = OFF;
 
                }
                if (blackActual > pwmCounter) {
                        BLACK     = ON;
                        } else {
                        BLACK     = OFF;
                }
 
                if (yellowActual > pwmCounter) {
                        YELLOW    = ON;
                        } else {
                        YELLOW    = OFF;
 
                }
                if (orangeActual > pwmCounter) {
                        ORANGE    = ON;
                        } else {
                        ORANGE    = OFF;
                }
 
                if (ashActual > pwmCounter) {
                        ASH       = ON;
                        } else {
                        ASH       = OFF;
 
                }
 
 
                pwmCounter++;
                if (pwmCounter > 80) {
                        pwmCounter = 0;
                }
                
                T0IF = 0;
        }
}

---

""

 

[betwixt]

I think you are doing it the wrong way around. At the moment you are continuously generating new targets then trying to reach them in an interrupt routine. The targets are being changed faster than you can reach them!

You should initially generate all targets ONCE then only when that target has been reached, generate a new target only for that color.

I do something almost identical in a product randomly fading 16 channels of different shades or red, orange, yellow and white to simulate a flame, also using a 16F877A.

Brian.

 

[thilan d]

dear betwixt,,, could you please advice me how i can make it work.. ?? can you change the code for me ? some how i can only light up 3 leds randomly and continuously
thank a lot

 

[betwixt]

I don't use the HTC compiler so there is no point in me trying out your code but this is how the flow should go:

In main()
1. Initialize all the pins etc. I think you have all the done correctly.
2. Generate all the random target values (as in lines 60 - 67)
3. In a while(1) loop
4. check if actual = target, if it is, generate a new random target.
5. check if actual > target, if it is, decrement 'actual' so it drops in value towards the target, if if is less than target, add one to it instead so it increases in value towards the target.
6. close the while loop
7. close main()

Then in the interrupt routine you produce the 'PWM' pulse length according to the 'actual' value.

It is essentially two programs, one running in main() to create random targets and move the 'actual' value towards it, the other in the interrupt routine to create the power to the LEDs according to the 'actual' value.

I cannot post the program for my 16 channel version for contractual reasons but I have attached a 10 channel version. It's in assembly language and compiles in MPLAB but you should be able to follow the way it works.
Ignore the 'C' code in the zip file, it was an experimental C version but was never completed.

Brian.

 

[thilan d]

betwixt am only able to light up 3 leds in port c
that is the issue am haveing with this code

do you have any idea to slove it ?

 

[betwixt]

Do you notice something different between this code:

                        if (redTarget > redActual)
                                redActual++;
                        else if (redTarget < redActual)
                                redActual--;
 
                        if (greenTarget > greenActual)
                                greenActual++;
                        else if (greenTarget < greenActual)
                                greenActual--;
 
                        if (blueTarget > blueActual)
                                blueActual++;
                        else if (blueTarget < blueActual)
                               blueActual--;

and this code:

if (brownActual > brownActual)
                                brownActual ++;
                        else if (brownActual < brownActual)
                                brownActual --;
 
                        if (blackActual > blackActual)
                                blackActual ++;
                        else if (blackActual < blackActual)
                                blackActual --;
 
                        if (yellowActual > yellowActual)
                                yellowActual ++;
                        else if (yellowActual < yellowActual)
                                yellowActual --;
 
                        if (orangeActual > orangeActual)
                                orangeActual ++;
 
                        else if (orangeActual < orangeActual)
                                orangeActual --;
 
                        if (ashActual > ashActual)
                                ashActual ++;
                        else if (ashActual < ashActual)
                                ashActual --;

With the exception of the first three colors you are asking if the same variable is greater than itself and less than itself - that doesn't make sense!

Brian.

 

[thilan d]

thank you Brian.
i was copy and paste the text
in word file before i compile
its the mistake that i done

how i can make it as a chaser now ?
can you please advice me ?