Pushbuttons only work on external circuit w/ gnd & reset pins attached from Ard

Using Arduino General Electronics
1

Hello,

I'm having a strange issue that I can't figure out. I am running a ATMEGA328 standalone and using a Arduino Uno sans chip to program it. Because I've used my all my other digital pins on other things like an LCD and L293D, I'm running 4 push buttons as digital on A0 to A3 (14-17). Everything on the circuit it working fine, LCD works, stepper works. Can upload sketches and get serial data to and from my computer. Weird thing is that my push buttons work fine when ground and reset from the arduino are attached, but do not when they are not. RX and TX can be disconnected and it works. To add to my confusion to get it to work BOTH ground and reset have to be attached, one and not the other, doesn't work. I'm powering the chip externally.

I think that about sums it up, let me know if you need more details.

Thanks
Dan

2

ground should be connected.

if it still doesn't work you're doing it wrong.
post your schematics.

ps. buttons should have 2 pins, say they're normally open, and when you push it it closes the circuit.
connect one end to A0/1/2/3, the other end to the ground, then enable the pull-up resistor.
to be save, put a current limitting resistor (you want something big like 47k or 68k, saves power.)

// Connect like this: A0 -- button -- GND
// or, to be safe: A0 -- resistor -- button -- GND
pinMode(A0, INPUT_PULLUP);
3

Something to add that I thought to try while I was typing.

I measured the voltage between the for the output of the switch. With no arduino connected it's 5v open and closed. with the arduino gnd and reset connected it's 2.14 open and 5 closed. With the gnd/reset/tx/rx connected it's 1.47 open and 5 closed.

Also I do have the button pulled to ground with a 10k resistor.

I admit am quite new at this, I feel like the answer will be obvious.

4

danparker:
Also I do have the button pulled to ground with a 10k resistor.

Try removing that resistor. You don't need it.

5

i think you have a connection problem, else you should read 5v open, 0v close.

6

I think you might be right. Actually, I know you are. I tried what fungus said and it didn't work on that particular button BUT the rest of them started working. So I cut the resistor off completely, soldered in a new one and now it works like a charm!

I wish I could say I knew exactly what the problem was though.

Thanks for your help gentlemen!

Dan