Arduino with 8 LEDs and a switch

Question

I have an assignment wherein we have 8 LEDs connected to an Arduino Uno which has a switch. These LEDs light up according to the johnson counter but every time I turn the switch off it should reset back to the start. An example is if I turned the switch off while the pin is at 8 going back to 1 , then when i turn it on it should be back to 1 again. I got the 1 to 8 reset part right but the 8 to 1, I'm having trouble solving.

Here is my code:

int pin;
int sw3 = 10;
void setup() {
 // put your setup code here, to run once:
 for (pin = 2; pin <= 9; pin++) {
 pinMode(pin, OUTPUT);
 }
 pinMode(sw3, INPUT);
}
void loop() {
 pin == 2;
 if (digitalRead(sw3) == HIGH) {
 for (pin = 2; pin <= 9; pin++) {
 digitalWrite(pin, HIGH);
 delay(200);
 }
 }
 else {
 digitalWrite(pin, LOW);
 }
 delay(200);
 for (pin = 2; pin <= 9; pin++)
 {
 digitalWrite(pin, LOW);
 }
 delay(200);
 if (digitalRead(sw3) == HIGH) {
 for (pin = 9; pin >= 2; pin--) {
 digitalWrite(pin, HIGH);
 delay(200);
 }
 }
 else {
 digitalWrite(pin, LOW);
 }
 delay(200);
 for (pin = 9; pin >= 2; pin--) {
 digitalWrite(pin, LOW);
 }
 delay(200);
 {
 if (digitalRead(sw3) == LOW) {
 digitalWrite(pin, LOW);
 }
 else {
 digitalWrite(pin, LOW);
 }
 }
}

• Gerben: I'm not able to comprehend what your problem is. The code also doesn't seem to do a johnson counter. Could you rephase your question, and maybe mark in your code where your problem is?

Answer 1

Some fixes:

pin==2; should only be 1 = here. == is a comparison.

pinMode(sw3,INPUT); make this INPUT_PULLUP, to turn on the internal pullup resistor

if(digitalRead(sw3)==HIGH){ change this to LOW, and wire your switch/button to connect the pin to GND when pressed. The internal pullup will unsure the pin is HIGH when not pressed, and the button/switch makes it LOW when pressed. The pin is thus not allowed to 'float' and return a random HIGH or LOW.

• Gerben: I think they are using an external pull-down.
• CrossRoads: the pin == 2 is probably the problem.