Hi there. This is a servo code originally from ermicro's blog. I modified it so that the pulse values can be increased and decreased for a max of 25(2.5ms) and min of 5(.5ms). I'm using push buttons to as the two increase/decrease inputs. I can see the interrupt and main loop working as the LEDs got toggled all the time, but when I pressed the buttons the servo didn't run at all. Here's the code:
Code:
//__CONFIG(INTIO & WDTDIS & PWRTEN & MCLREN & UNPROTECT \
// & UNPROTECT & BORDIS & IESODIS & FCMDIS);
// Using Internal Clock of 8 Mhz
#define FOSC 20000000L
#define _XTAL_FREQ 20000000
#define SW1 RB0
#define SW2 RB1
#define SERVO RC2
#define LED1 RB6
#define LED2 RB7
// Servo definition and variables
#define MAX_VALUE 200
#define CCW_ROTATION 180//MAX_VALUE - 23
#define CW_ROTATION 193 //MAX_VALUE - 5
#define STOP_ROTATION 185 //MAX_VALUE - 15
#define THRESHOLD_VALUE 50
unsigned char pulse_max=0;
unsigned char pulse_top=0;
unsigned char top_value = 0;
int VALVE = 25;
static void interrupt isr(void)
{
if(T0IF) { // TIMER0 Interrupt Flag
pulse_max++; // Pulse Max Increment
pulse_top++; // Pulse Top Increment
/* MAX_VALUE=200 turn off the pulse */
if (pulse_max >= MAX_VALUE)
{
pulse_max=0;
pulse_top=0;
SERVO=0; // Turn off RC2
//RB2=0;
LED1^ = 1;
}
/* top_value = MAX_VALUE - n, n=10: 10 x 0.1ms = 1.0ms, n=20: 20 x 0.1ms = 2.0ms */
/* 2ms -> CCW Rotation, 1ms -> CW Rotation */
if (pulse_top == VALVE)//top_value)
{
SERVO=1; // Turn On RC2
//RB2=1;
}
//TMR0 = 131; // Initial Value for 0.1ms Interrupt
TMR0 = 6;
T0IF = 0; // Clear TIMER0 interrupt flag
}
}
void main(void)
{
// OSCCON=0x70; // Select 8 Mhz internal clock
TRISB = 0b00000011; //configure PORTB I/O direction
TRISD = 0b00000000; //configure PORTD I/O direction
TRISA = 0b00000111; //configure PORTA I/O direction
PORTB = 0b00000000;
/* Initial Port Used */
TRISC = 0x00; // Set RC0 and RC1 as input others as Output
PORTC = 0x00; // Turn Off all PORTC
/* Init Servo Pulse */
pulse_max=0;
pulse_top=0;
top_value = MAX_VALUE; // top_value = MAX_VALUE: Servo Motor Stop
PEIE=1;
T0CS=0;
PSA = 0; // bit 3 Prescaler Assignment bit...0 = Prescaler is assigned to the Timer0
PS2 = 0; // bits 2-0 PS2:PS0: Prescaler Rate Select bits
PS1 = 0;
PS0 = 0;
TMR0 = 6; // preset for timer register
// OPTION = 0b00000000; // 1:2 Prescaller
//TMR0=156; // Interupt every 0.1 ms
T0IE = 1; // Enable interrupt on TMR0 overflow
GIE = 1; // Global interrupt enable
while(1) //Infinite loop
{
if(!SW1) //check if SW1 is pressed
{
VALVE++;
if(VALVE>=26)
{ VALVE=25;
}
}
if(!SW2) //check if SW2 is pressed
{
VALVE--;
if(VALVE<=4)
{ VALVE=5;
}
}
LED2^ = 1;
__delay_ms(250);
}
}
