/*
* Project: Blinking LED
* File: main.c
* Author: Spork Schivago
*
* Notice: Licensed under Creative Commons
* Attribution 4.0 International (CC BY 4.0)
* http://creativecommons.org/licenses/by/4.0/
*
* Version: 0.1
*
* Notes: Simple C program to control a PIC16F628A. The PIC
* will make 4 LEDs blink for a certain amount of time.
* The first LED blinks for a certain amount of time, then
* the second LED, the third, the fourth and it repeats.
*
* Created on December 18, 2015, 6:59 PM
*/
/* Set the clock frequency of the microcontroller
* to 4MHz so we can use the various delay() functions.
*/
#define _XTAL_FREQ 4000000
/* #pragma config statements should precede project file includes.
* Use project enums instead of #define for ON and OFF.
*/
/* Configuration Bits. */
#pragma config FOSC = INTOSCIO /* Oscillator Selection bits (INTOSC oscillator: I/O function on RA6/OSC2/CLKOUT pin, I/O function on RA7/OSC1/CLKIN). */
#pragma config WDTE = OFF /* Watchdog Timer Enable bit (WDT disabled). */
#pragma config PWRTE = ON /* Power-up Timer Enable bit (PWRT enabled). */
#pragma config MCLRE = OFF /* RA5/MCLR/VPP Pin Function Select bit (RA5/MCLR/VPP pin function is digital input, MCLR internally tied to VDD). */
#pragma config BOREN = ON /* Brown-out Detect Enable bit (BOD enabled). */
#pragma config LVP = ON /* Low-Voltage Programming Enable bit (RB4/PGM pin has digital I/O function, HV on MCLR must be used for programming). */
#pragma config CPD = OFF /* Data EE Memory Code Protection bit (Data memory code protection off). */
#pragma config CP = OFF /* Flash Program Memory Code Protection bit (Code protection off). */
#include <xc.h>
#include <stdint.h>
/* Setup some preprocessor definitions so we can
* keep track of the various pins a bit easier.
* RA0 is LED1, RA1 is LED2, RA2 is LED3 and
* RA3 is LED4.
*/
#define LED1 0b00000001 /* bitmask for pin RA0. */
#define LED2 0b00000010 /* bitmask for pin RA1. */
#define LED3 0b00000100 /* bitmask for pin RA2. */
#define LED4 0b00001000 /* bitmask for pin RA3. */
#define BTN_UP 0b00000001 /* bitmask for pin RB0. */
#define BTN_DWN 0b00000010 /* bitmask for pin RB1. */
volatile uint8_t sPORTA=0; /* Shadow register to hold the state of pin
* to prevent RMW problem.
*/
void init (void);
void blink_led (unsigned char led_bit, unsigned long time_ms);
void toggle_led (unsigned char led_bit);
void delay_ms(unsigned long milliseconds);
void main(void) {
uint8_t temp;
uint8_t count = 0;
init();
/* Blink all four LEDs once to show the user they're working. */
blink_led (LED1, 200);
blink_led (LED2, 200);
blink_led (LED3, 200);
blink_led (LED4, 200);
while(1) {
if(~PORTB & BTN_UP) {
count++; /* Increment counter. */
if(count==16) count = 0; /* We only have 4 LEDs so when we reach 16, reset. */
sPORTA = count; /* Store count value in memory. */
PORTA = sPORTA; /* Update PORTA with the shadow register contents. */
delay_ms(200); /* Delay to give switch a chance to stop bouncing. */
if(~PORTB & BTN_UP) {
while(~PORTB & BTN_UP); /* Loop until it's depressed. */
}
}
else if(~PORTB & BTN_DWN) { /* The user pressed the second button. */
count--; /* Decrement counter. */
if(count==255) count = 0; /* Since we're unsigned, negative will be 255. */
sPORTA = count; /* Store count value in memory. */
PORTA = sPORTA; /* Update PORTA with the shadow register contents. */
delay_ms(200); /* Delay to give switch a chance to stop bouncing. */
if(~PORTB & BTN_DWN) { /* If button is still pressed... */
while(~PORTB & BTN_DWN); /* Loop until it's depressed. */
}
}
}
}
/* Function to turn the LEDs on and off every second. */
void blink_led (unsigned char led_bit, unsigned long time_ms) {
sPORTA |= led_bit; /* Modify the shadow register (to prevent RMW). */
PORTA = sPORTA; /* Update PORTA with the shadow register to turn ON the LED. */
delay_ms(time_ms); /* Wait 1s. */
sPORTA &= ~led_bit; /* Modify the shadow register. */
PORTA = sPORTA; /* Update PORTA with the shadow register to turn OFF the LED. */
}
void toggle_led (unsigned char led_bit) {
sPORTA ^= led_bit; /* Toggle the bit stored in led_bit. */
PORTA = sPORTA; /* Update PORTA with the shadow register contents. */
}
void delay_ms(unsigned long milliseconds) {
while(milliseconds > 0) {
__delay_ms(1);
milliseconds--;
}
}
/* Function to setup the various control registers
* and set the direction of the various I/O pins
*/
void init(void) {
CMCON = 0x07; /* Turn comparators off and enable pins
* for I/O functions CM<2:0> = 0b111
*/
OPTION_REGbits.nRBPU = 0; /* Enable the weak pull-up resistors on PORTB. */
/* Set the directions of the various pins
* by manipulating the tri-state registers
*/
/* pin number
* 76543210
*/
TRISA = 0b00000000; /* Set all PORTA pins to output. */
TRISB = 0b00000011; /* Set ports RB0:1 to inputs. */
PORTA = 0; /* Set all PORTA bits to low by default. */
PORTB = 1; /* Set all PORTB bits to high by default. */
}
Comment