Electronic – How to get two buttons to work with the 16f628a – C, Hi-tech comp, mplabx

blinkchi-tech-compilermicrocontrollerpic

I'm just began exploring my new hobby – mcu electronics. I have bought an 16f628a after reading some forumposts suggestion that is a good mcu for beginners.
I have download mplabX, the hi-tech compiler and the isis program for simulating my circuit and code. I have some knowledge from c# and java development, so I like working with their "mother language" C. I have allready created the "hello world" and "blinking led" project.

Now I want to add two buttons to my blinking led prosject (one for each led. One pin for each led and one pin for each button, everthing happening programmatically), I have been searching the Internet and found some examples and tutorials but not any that I got to work.

If any got some links to tutorials / examples, code snippets with schematics or anything else that will help me create this I would appreciate it. I can post my blinking led code and schematics if that would help. thanks

Best Answer

I am an experienced C# developer that wanted to get quickly up to speed on the PICs and found these tutorials to be very helpful:

http://www.gooligum.com.au/tutorials.html

The are kept up-to-date with recent MPLAB versions. A lot of them are free. I liked them enough that I paid for the full set. They are geared to his learning kit, but I used them with just a breadboard and a PicKit3.

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Electronic – Fast PWM and Atmega1280 problem

Ok I can see a few problems with this code (Im assuming this is your datasheet):

First of all, if you want smooth fading use the 16-bit Timer instead of 8-bit (TCCR1A)
You want Fast PWM however you have it set to Phase Correct (pg 148, you want Mode 14)
You are not indicating the Frequency you want, in Fast PWM mode, according to the datasheet you need to set the TOP value, to do this you need to perform some calculation (formula on page 152 at the top).
Once you computed your TOP, the ICR1 needs to be set to that value (use a prescaler if your number is greater than 65535, table on pg 161)
To enable PWM on OC0A (PINB7) you need to set both COM0A1 & COM0A0

Refer to this example, its for the Atmega128 and uses a 16 bit timer. The frequency is 120Hz and my CPU clock speed is 16MHz. Therefore by using the formula I ended up with a TOP (16665) and my prescaler was 8 I believe.

#include <avr/io.h>
#include <util/delay.h>

int main(void) {

    //Fast PWM, using inverted mode (default low)
    TCCR1A |= 1<<WGM11 | 1<<COM1A1 | 1<<COM1A0;
    TCCR1B |= 1<<WGM12 | 1<<WGM13 | 1<<CS11;

    //Top
    ICR1 = 16665;

    //Set pins to input/output

    DDRB |= 1<<PINB5;

    OCR1A = 0;

    while(1) {
        //continuous loop where everything happens
        int i;

        for(i=0; OCR1A<ICR1; i+=166) {
            OCR1A = i;
            _delay_ms(6);
        }

        for(i=0; i<ICR1; i+=166) {
            OCR1A = ICR1 - i;
            _delay_ms(6);
        }

        OCR1A = 0;
        _delay_ms(500);

    }

}

Electronic – PIC12 TRIS Register not setting, No GP0 GP2 output

The problem of TRIS not updating appears to be a bug in MPLAB X's PIC508 simulator core. I complied your code with MPLAB X and it failed in the simulator. I then loaded the hex file into MPLAB 8.92 and it simulated perfectly.

I recommend using MPLAB 8.92 for low-end chips until (if ever) they get the bugs out of MPLAB X, but if you want to continue using MPLAB X then switch the processor to PIC12F508 (which doesn't have this problem).

Best Answer

Related Solutions

Electronic – Fast PWM and Atmega1280 problem

Electronic – PIC12 TRIS Register not setting, No GP0 GP2 output

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