Digital Read

Projects Programming
1

HI

I am trying to read 24 digital inputs as part of a project I am working on. Also to teach me more about coding.

The problem is that for some reason my Arduino Mega does not latch the reading when it is high.

I have started small, only 2 channels with the hopes of making them work and then add more channels as I go, and also learn better ways to do the code.

At the moment, when I remove the jumper from the 5V of the Arduino to PIN22 it displays the Channel number in the right line on the LCD.

But when I put it back in 5V pin it simply bounces between HIGH and LOW on the LCD display, as if it reads it HIGH and LOW at the same time.

I have tried many combinations of code and simply cannot get a stable HIGH reading...

PLEASE can anyone assist in showing me my mistake?

As you can see from PHOTO, the 22 is dimm as it is jumping HIGH and LOW

20180915_210341.jpg
20180915_210341.jpg1885×1060 213 KB

RippleReader2.ino (1.28 KB)

2

Please post code in your post (using code tags) instead of attaching it (if size allows; 9000 byte limit).

OP's code

#include <Wire.h>
#include <LiquidCrystal_I2C.h>


LiquidCrystal_I2C lcd(0x27, 20, 4);

const int RippleChannel[] = {22, 23};
int channelstate = 0;


void setup() {

  pinMode (RippleChannel[0], INPUT);
  pinMode (RippleChannel[1], INPUT);
  digitalWrite(RippleChannel[0], HIGH);
  digitalWrite(RippleChannel[1], HIGH);


  lcd.init();
  lcd.backlight();
  Serial.begin(9600);


  lcd.setCursor(0, 0);
  lcd.print("Channels ON");
  lcd.setCursor(0, 2);
  lcd.print("Channels OFF");



}



void loop() {

  channelstate = digitalRead(RippleChannel[0]);

  if (digitalRead(RippleChannel[0]) == HIGH )
  {


    lcd.setCursor(0, 1);
    lcd.print(RippleChannel[0]);
    lcd.setCursor(0, 3);
    lcd.print("  ");
    delay(100);

  }

  else (digitalRead(RippleChannel[0]) == LOW);

  {

    lcd.setCursor(0, 1);
    lcd.print("  ");
    lcd.setCursor(0, 3);
    lcd.print(RippleChannel[0]);
    delay(100);


  }

  channelstate = digitalRead(RippleChannel[1]);

  if (channelstate == HIGH)
  {

    lcd.setCursor(3, 1);
    lcd.print(RippleChannel[1]);
    lcd.setCursor(3, 3);
    lcd.print("  ");
    delay(100);

  }

  else if (channelstate == LOW);

  {

    lcd.setCursor(3, 1);
    lcd.print("  ");
    lcd.setCursor(3, 3);
    lcd.print(RippleChannel[1]);
    delay(100);


  }
  return (0);
}

You have configured your inputs to use the internal pullup resistor; in which case the jumper / switch must be wired between pin and GND. So I do not understand what you mean by At the moment, when I remove the jumper from the 5V of the Arduino

The below should just be a else; else does not take a condition.

  else (digitalRead(RippleChannel[0]) == LOW);

And why is there a semicolon at the end?

3 
channelstate = digitalRead(RippleChannel[0]);

  if (digitalRead(RippleChannel[0]) == HIGH )
  {

Why read a value into channelstate and then ignore that and repeat the digitalRead()s?

else (digitalRead(RippleChannel[0])== LOW);

I'm not sure exactly what you intended here. Did you just leave the if out? And the ; almost certainly shouldn't be there.

Steve