Hey everybody. I am going through the lessons for Pickit 3's Debug Express and I am a little stuck on Lesson 5, which introduces the use of Timer0. I have Pickit3 connected to the Development Board, and I am using USB to power the target. I took the lesson code directly from the install, built it, no errors, program the chip, no errors. The problem is that the output does not work as expected. It's supposed to shift through the LED's, incrementing or decrementing when Timer0 expires and resets, and shift direction when the input button is pressed. Unfortunately, it doesn't do anything. This is the first issue I have had with it and all other lessons have worked great!
Here's the Lesson 5 C code. Can anyone see a glaring error that's causing it to hiccup? I'm a decent C coder but admittedly, I don't know the hardware that well yet.
Thanks in advance for any help provided.
-Eric
Here's the Lesson 5 C code. Can anyone see a glaring error that's causing it to hiccup? I'm a decent C coder but admittedly, I don't know the hardware that well yet.
Thanks in advance for any help provided.
-Eric
Rich (BB code):
/** C O N F I G U R A T I O N B I T S ******************************/
#pragma config FOSC = INTIO67, FCMEN = OFF, IESO = OFF // CONFIG1H
#pragma config PWRT = OFF, BOREN = OFF, BORV = 30 // CONFIG2L
#pragma config WDTEN = OFF, WDTPS = 32768 // CONFIG2H
#pragma config MCLRE = ON, LPT1OSC = OFF, PBADEN = ON, CCP2MX = PORTC // CONFIG3H
#pragma config STVREN = ON, LVP = OFF, XINST = OFF // CONFIG4L
#pragma config CP0 = OFF, CP1 = OFF, CP2 = OFF, CP3 = OFF // CONFIG5L
#pragma config CPB = OFF, CPD = OFF // CONFIG5H
#pragma config WRT0 = OFF, WRT1 = OFF, WRT2 = OFF, WRT3 = OFF // CONFIG6L
#pragma config WRTB = OFF, WRTC = OFF, WRTD = OFF // CONFIG6H
#pragma config EBTR0 = OFF, EBTR1 = OFF, EBTR2 = OFF, EBTR3 = OFF // CONFIG7L
#pragma config EBTRB = OFF // CONFIG7H
/** I N C L U D E S **************************************************/
#include "p18f45k20.h"
//#include "delays.h" // no longer being used.
#include "05 Timer.h" // header file
/** V A R I A B L E S *************************************************/
#pragma udata // declare statically allocated uinitialized variables
unsigned char LED_Display; // 8-bit variable
/** D E C L A R A T I O N S *******************************************/
#pragma code // declare executable instructions
void main (void)
{
LEDDirections Direction = LEFT2RIGHT;
BOOL SwitchPressed = FALSE;
LED_Display = 1; // initialize
// Init I/O
TRISD = 0b00000000; // PORTD bits 7:0 are all outputs (0)
INTCON2bits.RBPU = 0; // enable PORTB internal pullups
WPUBbits.WPUB0 = 1; // enable pull up on RB0
ANSELH = 0x00; // AN8-12 are digital inputs (AN12 on RB0)
TRISBbits.TRISB0 = 1; // PORTB bit 0 (connected to switch) is input (1)
// Init Timer
INTCONbits.TMR0IF = 0; // clear roll-over interrupt flag
T0CON = 0b00001000; // no prescale - increments every instruction clock
//T0CON = 0b00000001; // prescale 1:4 - four times the delay.
TMR0H = 0; // clear timer - always write upper byte first
TMR0L = 0;
T0CONbits.TMR0ON = 1; // start timer
while (1)
{
if (Direction == LEFT2RIGHT)
{
LED_Display <<= 1; // rotate display by 1 from 0 to 7
if (LED_Display == 0)
LED_Display = 1; // rotated bit out, so set bit 0
}
if (Direction == RIGHT2LEFT)
{
LED_Display >>= 1; // rotate display by 1 from 7 to 0
if (LED_Display == 0)
LED_Display = 0x80; // rotated bit out, so set bit 7
}
LATD = LED_Display; // output LED_Display value to PORTD LEDs
do
{ // poll the switch while waiting for the timer to roll over.
if (Switch_Pin == 1)
{ // look for switch released.
SwitchPressed = FALSE;
}
else if (SwitchPressed == FALSE) // && (Switch_Pin == 0) due to if-else
{ // switch was just pressed
SwitchPressed = TRUE;
// change direction
if (Direction == LEFT2RIGHT)
Direction = RIGHT2LEFT;
else
Direction = LEFT2RIGHT;
}
} while (INTCONbits.TMR0IF == 0);
// Timer expired
INTCONbits.TMR0IF = 0; // Reset Timer flag
}
}
)
