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Lab Week 9: Void Loop (Digitalwrite (Led - Builtin, High) Delay (833) Digitalwrite (Led - Builtin, Low) Delay (167) )

The document discusses blinking an LED at 0.5 Hz and controlling LEDs using UART serial interface. It also covers debouncing a switch using an interrupt attached to the switch pin. The assignment code uses a switch to toggle an LED that blinks a set number of times each time the switch is pressed.

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Kunal Sharma
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96 views1 page

Lab Week 9: Void Loop (Digitalwrite (Led - Builtin, High) Delay (833) Digitalwrite (Led - Builtin, Low) Delay (167) )

The document discusses blinking an LED at 0.5 Hz and controlling LEDs using UART serial interface. It also covers debouncing a switch using an interrupt attached to the switch pin. The assignment code uses a switch to toggle an LED that blinks a set number of times each time the switch is pressed.

Uploaded by

Kunal Sharma
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Lab Week 9

1.3: Blinking frequency = 1 / (ton+toff) = 1/2 = 0.5 Hz.


1.4: ton=0.2toff, ton+toff=1/freq=1, 0.2toff+toff = 1  toff =1/1.2 ≈ 0.833s, ton ≈ 0.167s

void loop() {
digitalWrite(LED_BUILTIN, HIGH);
delay(833);
digitalWrite(LED_BUILTIN, LOW);
delay(167);
}

2.2: Hello World shows up on the serial monitor.


2.4: UART serial interface is used to control the LEDs. The code checks each received
character as follows:
'1' : to turn on LED0.
'2' : to turn off LED0.
'3' : to turn on LED1.
'4' : to turn off LED1.

3.2: Each time the switch is pressed the on-board LED toggles. The existence of switch
bouncing can be expected.

3.3: ASSIGNMENT

#define BLINK_NUM 5
#define SW 2

volatile unsigned int led_state = LOW;


volatile unsigned int sw_flag = 0;
volatile unsigned int cnt = 0;

void setup() {
pinMode(LED_BUILTIN,OUTPUT);
pinMode(SW,INPUT_PULLUP);
attachInterrupt(digitalPinToInterrupt(SW),fToggle,FALLING);
digitalWrite(LED_BUILTIN,led_state);
}

void loop() {
if (sw_flag) {
if (cnt<2*BLINK_NUM) {
digitalWrite(LED_BUILTIN,led_state);
delay(500);
led_state = !led_state;
cnt++;
} else {
sw_flag = 0;
}
}
}

void fToggle() {
sw_flag = 1;
cnt = 0;
}

3.4: Switch debouncing using delay(). The LEDs toggle each time the switch is pressed.
4.2: The on-board LED's brightness can be controlled by the potentiometer.

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