(4) If the PB7 pin is high, Increment the variable ent by 1, and output ent Retu
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Question
(4) If the PB7 pin is high, Increment the variable ent by 1, and output ent Return from interrupt (s) If the PB7 pin is low, decrement the variable cnt by 1, and output cnt to Return from interrupt. Solution: to PORTD OUT PORTD OUT 2. Write an instruction sequence to perform the following operations: (a) Place PORTB pins PB7, PB2, and PBo to INT1 group (8 points) (b) Place PORTB INTI group in high priority interrupt (c) Enable high priority interrupt (d) Enable interrupt globally Solution: 3. Modify Example 8.1 (in power-point), and write a subroutine to generate a delay which is exactly 23 ms using timer TCF1 and return assuming that fax PER·32 MHz, (10 points) Solution: Set the timer clock prescaler to 64. The timer clock input frequency is 50o kHz. The timer count to generate the specified delay is 500 x 103 x 23 x 10311500 delay23ms:Explanation / Answer
const int buttonPin = 2; // the number of the pushbutton pin
const int ledPin = 13; // the number of the LED pin
// Variables will change:
int ledState = HIGH; // the current state of the output pin
int buttonState; // the current reading from the input pin
int lastButtonState = LOW; // the previous reading from the input pin
int count=0;
// the following variables are unsigned long's because the time, measured in miliseconds,
// will quickly become a bigger number than can be stored in an int.
unsigned long lastDebounceTime = 0; // the last time the output pin was toggled
unsigned long debounceDelay = 50; // the debounce time; increase if the output flickers
void setup() {
Serial.begin(9600);
pinMode(buttonPin, INPUT);
pinMode(ledPin, OUTPUT);
// set initial LED state
digitalWrite(ledPin, ledState);
}
void loop() {
// read the state of the switch into a local variable:
int reading = digitalRead(buttonPin);
// check to see if you just pressed the button
// (i.e. the input went from LOW to HIGH), and you've waited
// long enough since the last press to ignore any noise:
// If the switch changed, due to noise or pressing:
if (reading != lastButtonState) {
// reset the debouncing timer
lastDebounceTime = millis();
}
if ((millis() - lastDebounceTime) > debounceDelay) {
// whatever the reading is at, it's been there for longer
// than the debounce delay, so take it as the actual current state:
// if the button state has changed:
if (reading != buttonState) {
buttonState = reading;
// only toggle the LED if the new button state is HIGH
if (buttonState == HIGH) {
ledState = !ledState;
count++;
Serial.println(count);
}
}
}
// set the LED:
digitalWrite(ledPin, ledState);
// save the reading. Next time through the loop,
// it'll be the lastButtonState:
lastButtonState = reading;
}??
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