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Projects General Guidance
21

The Arduino pins are your inputs then, right?

I think the problem is that your switches have a pretty high resistance as you said before (did you measure this already?), so they may not be able to pull the signal sufficiently high when your shift register output is high.

Possible solution: increase the value of those resistors to something like 2-5 times the highest button resistance. Then you can be sure it pulls the signal up enough to be registered as "high" on your pin.

Then there may another problem: signal slowness. You may have to go to 1 M resistors, and your setup will have stray capacitance. Just 1 pF stray capacitance (fair chance you have more) and your pins take about 1 microsecond to change level. So you have to give your pins sufficient time after setting your register - reading instantly after setting your register pin high and another low may cause you to still read the previous button.

Before you also mentioned an LED - how is that wired?

22

wvmarle:
Before you also mentioned an LED - how is that wired?

i was using the Arduino Switch Tutorial to test the keys to see if they were even making connections

23

EdWino:
i was using the Arduino Switch Tutorial to test the keys to see if they were even making connections

most of the keys were not, from what i feel is lack of juice. the led would become more dim as i stepped on the pad further away from the arduino

24

You don't have a meter?

If I give you code to test a switch without one, will you try it?

25

GoForSmoke:
You don't have a meter?

If I give you code to test a switch without one, will you try it?

ya sure!

26

This sketch allows you to test switches wired for pins moded INPUT or INPUT_PULLUP.
I recommend the latter as safer, less current draining and needing less circuit.

Be sure to read the comments and if you have ANY doubts about wiring, get them answered
before powering up! I know my forum name is GoForSmoke but let's not instead!

I did test this with only a jumper and nothing went poof.

Note that the led is not powered through the switch. That messes with circuit, the led drops
about a volt and a half from the circuit. The Uno turns the led on when a switch is 'pressed'.

// switch tester -- test a switch circuit (or two) using different pin modes
// I tested this on an Uno R3 with a jumper, it worked.
// Free for use, by Arduino.cc forum GoForSmoke, Sept 17, 2017

// If not testing using INPUT then jumper inPin to ground so it won't 'float'
// If testing using INPUT then be sure to wire a pulldown to inPin
// You can also comment out the inPin lines if you don't want to test using INPUT

// Arduino INPUT_PULLUP pin mode supplies weak power to the moded pin. All you have
// to do is ground it enough to take it LOW to be detected. It is ground-safe pin mode.

// If your switch is in a matrix then it would be best to add a diode between the sense
// pin and the switch, pointing at the switch. The diode prevents two switches in the
// matrix pressed at once from being seen as four switches. It also drops .7V so for
// electrical purposes, test the switch with the diode.
// However if you only want to test the switch then you don't need the diode.

#include "Arduino.h"

byte inPin = 3; // pin to test switch using INPUT
byte puPin = 7; // pin to test switch using INPUT_PULLUP

byte led13 = 13;
byte lightUp; // default is 0

void setup()
{
  pinMode( led13, OUTPUT );
  pinMode( inPin, INPUT ); // 5V goes to pin on press
  pinMode( puPin, INPUT_PULLUP ); // 5V goes from pin on press
}

void loop()
{
  if ( digitalRead( inPin ) == HIGH )
  {
    lightUp = 1;
  }
  if ( digitalRead( puPin ) == LOW )
  {
    lightUp = 1;
  }
  digitalWrite( led13, lightUp );
  lightUp = 0;
}