Finally, last night I had some time to spare... enough to fire up MPLAB, Microchip's microcontroller development studio. I'd spent some time trying to learn to program in assembler, then in C, but gave up in frustration. But, as any true geek knows, projects like this keep on nagging in the back of your mind. So, I decided to give it another go, this time trying to make a counter on the LED display of my homemade controller board, using a PIC16F630:
For some reason, this 16F630 controller never, ever does what it's supposed to do, at least not in my world. This time however, I was determined to get the bastard to submit to my will, instead of the other way around! After an hour or so, I came up with the following:
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//Includes & references
#include <htc.h>
//Processor configuration (look in processor header file for definitions)
__CONFIG(FOSC_INTRCIO & WDTE_OFF & PWRTE_OFF & BOREN_OFF &
MCLRE_OFF & CPD_OFF & CP_OFF);
#define _XTAL_FREQ 4000000
#define DIGIT0 RA0
#define DIGIT1 RA1
#define DIGIT2 RA2
#define BUTTON1 RA5
//Global variables
//int counter = 0;
//Put initialization code here
void init (void)
{
//Disable interrupts
INTCON = 0b00000000;
PIE1 = 0b00000000;
//Set options
OPTION_REG = 0b10000111;
//Switch off comparator to enable digital I/0
CMCON = 0b00000111;
//Set port directions
TRISA = 0b00101000;
TRISC = 0b00000000;
//T1CON = 0b00110101;
}
/**** Function prototypes ****/
void ShowDigit (int Number);
/**** Main function block ****/
void main (void)
{
init();
int count = 0;
int i = 0;
for (;;)
{
//Blank display before digit switch
ShowDigit(11);
switch (i)
{
case (0):
//Digit 2 (MSB)
//PORTA = 0b11111011;
DIGIT0 = 1;
DIGIT1 = 1;
DIGIT2 = 0;
break;
case (1):
//Digit 1
//PORTA = 0b11111101;
DIGIT0 = 1;
DIGIT1 = 0;
DIGIT2 = 1;
break;
case (2):
//Digit 0 (LSB)
//PORTA = 0b11111110;
DIGIT0 = 0;
DIGIT1 = 1;
DIGIT2 = 1;
break;
default:
//PORTA = 0b11111111;
;
}
//Show next number
ShowDigit(count);
__delay_ms(500);
i++;
if (i > 2)
i = 0;
count++;
if (count > 9)
count = 0;
//Reset counters when sw1 is pressed
if (!BUTTON1)
{
i = 0;
count = 0;
}
}
}
/**** Functions ****/
//Call with 0 - 9 to show digit. All other values blank the display.
void ShowDigit (int Number)
{
switch (Number)
{
case (0):
PORTC = 0b000000;
RA4 = 1;
break;
case (1):
PORTC = 0b111001;
RA4 = 1;
break;
case (2):
PORTC = 0b100100;
RA4 = 0;
break;
case (3):
PORTC = 0b110000;
RA4 = 0;
break;
case (4):
PORTC = 0b011001;
RA4 = 0;
break;
case (5):
PORTC = 0b010010;
RA4 = 0;
break;
case (6):
PORTC = 0b000010;
RA4 = 0;
break;
case (7):
PORTC = 0b111000;
RA4 = 1;
break;
case (8):
PORTC = 0b000000;
RA4 = 0;
break;
case (9):
PORTC = 0b010000;
RA4 = 0;
break;
default:
//Defaults to blank
PORTC = 0b111111;
RA4 = 1;
}
}
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Predictably, this did not work... at first. The output ports would not react the way I wanted, resulting in strange characters on the display. As a last resort, i turned to the 16F630 manual. And Eureka! Because of the fact that many of the controller's pins have multiple functions, it is very important to set up the peripherals correctly. Switching off the internal comparator by including the command:
CMCON = 0b00000111;
did the trick! So now i've got a 3-digit counter of sorts, which counts from 0 to 9 across the 3 digits, and resets when a button is pressed. Next step is to implement multiplexing, and make this into a useful counter / stopwatch. Also, the button should activate an interrupt, making it more responsive. The way things are going, this may take another year.. but hey, at least now it works!
Update: Let's watch the result:
