3 Count Up on LEDs Using Interrupts as Delay
This example uses the same device and Port A LEDs as the previous example. This example is a modification of the previous code. Although the delay loop in the previous example was useful in slowing down loop execution, it created dead time in the program. To avoid this, a timer interrupt can be used.
// PIC18F47Q10 Configuration Bit Settings
// 'C' source line config statements
// CONFIG1L
#pragma config FEXTOSC = OFF // External Oscillator mode Selection bits (Oscillator not enabled)
#pragma config RSTOSC = HFINTOSC_1MHZ// Power-up default value for COSC bits (HFINTOSC with HFFRQ = 4 MHz and CDIV = 4:1)
// CONFIG1H
#pragma config CLKOUTEN = OFF // Clock Out Enable bit (CLKOUT function is disabled)
#pragma config CSWEN = ON // Clock Switch Enable bit (Writing to NOSC and NDIV is allowed)
#pragma config FCMEN = ON // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor enabled)
// CONFIG2L
#pragma config MCLRE = EXTMCLR // Master Clear Enable bit (MCLR pin (RE3) is MCLR)
#pragma config PWRTE = OFF // Power-up Timer Enable bit (Power up timer disabled)
#pragma config LPBOREN = OFF // Low-power BOR enable bit (Low power BOR is disabled)
#pragma config BOREN = SBORDIS // Brown-out Reset Enable bits (Brown-out Reset enabled , SBOREN bit is ignored)
// CONFIG2H
#pragma config BORV = VBOR_190 // Brown Out Reset Voltage selection bits (Brown-out Reset Voltage (VBOR) set to 1.90V)
#pragma config ZCD = OFF // ZCD Disable bit (ZCD disabled. ZCD can be enabled by setting the ZCDSEN bit of ZCDCON)
#pragma config PPS1WAY = ON // PPSLOCK bit One-Way Set Enable bit (PPSLOCK bit can be cleared and set only once; PPS registers remain locked after one clear/set cycle)
#pragma config STVREN = ON // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config XINST = OFF // Extended Instruction Set Enable bit (Extended Instruction Set and Indexed Addressing Mode disabled)
// CONFIG3L
#pragma config WDTCPS = WDTCPS_31// WDT Period Select bits (Divider ratio 1:65536; software control of WDTPS)
#pragma config WDTE = OFF // WDT operating mode (WDT Disabled)
// CONFIG3H
#pragma config WDTCWS = WDTCWS_7// WDT Window Select bits (window always open (100%); software control; keyed access not required)
#pragma config WDTCCS = SC // WDT input clock selector (Software Control)
// CONFIG4L
#pragma config WRT0 = OFF // Write Protection Block 0 (Block 0 (000800-003FFFh) not write-protected)
#pragma config WRT1 = OFF // Write Protection Block 1 (Block 1 (004000-007FFFh) not write-protected)
#pragma config WRT2 = OFF // Write Protection Block 2 (Block 2 (008000-00BFFFh) not write-protected)
#pragma config WRT3 = OFF // Write Protection Block 3 (Block 3 (00C000-00FFFFh) not write-protected)
#pragma config WRT4 = OFF // Write Protection Block 4 (Block 4 (010000-013FFFh) not write-protected)
#pragma config WRT5 = OFF // Write Protection Block 5 (Block 5 (014000-017FFFh) not write-protected)
#pragma config WRT6 = OFF // Write Protection Block 6 (Block 6 (018000-01BFFFh) not write-protected)
#pragma config WRT7 = OFF // Write Protection Block 7 (Block 7 (01C000-01FFFFh) not write-protected)
// CONFIG4H
#pragma config WRTC = OFF // Configuration Register Write Protection bit (Configuration registers (300000-30000Bh) not write-protected)
#pragma config WRTB = OFF // Boot Block Write Protection bit (Boot Block (000000-0007FFh) not write-protected)
#pragma config WRTD = OFF // Data EEPROM Write Protection bit (Data EEPROM not write-protected)
#pragma config SCANE = ON // Scanner Enable bit (Scanner module is available for use, SCANMD bit can control the module)
#pragma config LVP = ON // Low Voltage Programming Enable bit (Low voltage programming enabled. MCLR/VPP pin function is MCLR. MCLRE configuration bit is ignored)
// CONFIG5L
#pragma config CP = OFF // UserNVM Program Memory Code Protection bit (UserNVM code protection disabled)
#pragma config CPD = OFF // DataNVM Memory Code Protection bit (DataNVM code protection disabled)
// CONFIG5H
// CONFIG6L
#pragma config EBTR0 = OFF // Table Read Protection Block 0 (Block 0 (000800-003FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF // Table Read Protection Block 1 (Block 1 (004000-007FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF // Table Read Protection Block 2 (Block 2 (008000-00BFFFh) not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF // Table Read Protection Block 3 (Block 3 (00C000-00FFFFh) not protected from table reads executed in other blocks)
#pragma config EBTR4 = OFF // Table Read Protection Block 4 (Block 4 (010000-013FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR5 = OFF // Table Read Protection Block 5 (Block 5 (014000-017FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR6 = OFF // Table Read Protection Block 6 (Block 6 (018000-01BFFFh) not protected from table reads executed in other blocks)
#pragma config EBTR7 = OFF // Table Read Protection Block 7 (Block 7 (01C000-01FFFFh) not protected from table reads executed in other blocks)
// CONFIG6H
#pragma config EBTRB = OFF // Boot Block Table Read Protection bit (Boot Block (000000-0007FFh) not protected from table reads executed in other blocks)
// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.
#include <xc.h>
// Interrupt function (see 3.1 The Interrupt Function)
void __interrupt() tcInt(void){
// only process timer0-triggered interrupts
if(PIE0bits.TMR0IE && PIR0bits.TMR0IF) {
static uint8_t portValue;
LATA = (portValue++); // write to port latch RA[4:7] = LED[2:5]
PIR0bits.TMR0IF = 0; // clear this interrupt condition
}
}
void main(void) {
// Port A access
ANSELA = 0x0; // set to digital I/O (not analog)
TRISA = 0x0; // set all port bits to be output
// Timer0 setup (see 3.2 Timer0 Setup)
T0CON0 = 0x10; // timer 0 16-bit
T0CON1 = 0x70; // internal timer, asynch
T0CON0bits.T0EN = 1; // enable timer 0
PIE0bits.TMR0IE = 1; // enable interrupts for timer 0
ei(); // enable all interrupts
while(1);
return;
}