Add an interrupt the Left to Right direction sequence when RD6 is pressed on Explorer 16

Question

Add an interrupt the Left to Right direction sequence when RD6 is pressed on Explorer 16

unsigned int count1 = 500;
unsigned int count2 = 500;
unsigned int timerValue = 0;

int main(void){
TRISA = 0x00; // Set PORTA as output
TRISDbits.TRISD6 = 1; // Set SW3 input

int i;
int j;

while(1) {
// Toggle RUN LED (D10) every 3.5 seconds using Timer1
LATDbits.LATD0 = !LATDbits.LATD0;
delayFunc();

// Knight Rider pattern from Left to Right direction
for(i = 0; i <= 6; i++) {
LATA = (1 << i);
delayFunc();
}

// Knight Rider pattern: Left to Right or Right to Left depending on SW3 state
if (PORTDbits.RD6 == 0) {
for(j = 6; j >= 0; j--) {
LATA = (1 << j);
delayFunc();
}
} else {
for( j = 0; j <= 7; j++) {
LATA = (1 << j);
delayFunc();
}
}
}

return -1;

}

void delayFunc(void)
{
int j,k;
int a;

for(j = 0; j < count1; j++)
{
for(k=0; k < count2; k++)
{
a = 0;
}
}
}

Answer 1

To add an interrupt to the Left to Right direction sequence when RD6 is pressed on the Explorer 16 board, follow these steps:

1. Declare an interrupt function at the beginning of the code:
```c
void __attribute__((interrupt, no_auto_psv)) _INT0Interrupt(void)
{
// Set the interrupt flag back to 0
IFS0bits.INT0IF = 0;

// Knight Rider pattern from Left to Right direction
for(int i = 0; i <= 6; i++) {
LATA = (1 << i);
delayFunc();
}
}
```

2. Enable the external interrupt and set its priority in the `main` function:
```c
int main(void)
{
// ...

// Enable external interrupt on RD6/INT0 and set its priority
INTCON2bits.INT0EP = 1; // Detect falling edge
IPC0bits.INT0IP = 4; // Set priority to 4
IEC0bits.INT0IE = 1; // Enable the interrupt

while(1) {
// ...
}

// ...
}
```

3. In the `while(1)` loop, add a check for the interrupt flag to toggle the Knight Rider pattern direction based on the state of RD6:
```c
while(1) {
// ...

// Knight Rider pattern: Left to Right or Right to Left depending on SW3 (RD6) state
if (PORTDbits.RD6 == 0) {
for(j = 6; j >= 0; j--) {
LATA = (1 << j);
delayFunc();
}
} else {
for( j = 0; j <= 7; j++) {
LATA = (1 << j);
delayFunc();
}
}
}
```

4. Implement a delay function to provide a delay between LED changes in the Knight Rider pattern. You can use the existing `delayFunc` function in the code.