Matrix keypad with pins 0 and 1

Using Arduino Programming Questions
1

I've got a project I'm building using an older Arduino Uno.
Every pin is used so I can't just switch around to solve my problem.

I have a 4x4 matrix keypad connected. The row assignments are working fine. The columns are not, though.

I'm using pins 0,1,2,6 for the columns. I get proper values from the pin 2 and pin 6 columns but the 0 and 1 columns are not working at all. I've confirmed continuity end to end and have switched from my own sketch to a barebones matrix keypad sketch. If I switch from {0,1,2,6} to {6,2,1,0} I get the same failure of pins 1 and 0.

I understand that pins 0 and 1 are different in that they are serial port pins. Is there some special way to handle these pins for the keypad?

Thanks!

2

Is there some special way to handle these pins for the keypad?

No, just don't use them.

Have you used all/any of the analogue pins in your project ?

3

Yep - the only pin not used is 10 because I need it for hardware SPI.

Are you saying there's no modification I can make to get this to work?

4

Oh I just had an epiphany.

It's my troubleshooting that's causing the problem. I used Serial.print to see if the keypad is working right. But by doing so I caused it to fail. As soon as I used the Serial.begin(9600); it turned pins 0 and 1 into Tx/Rx and they no longer worked for digital i/o.

Sheesh.

Thanks for your time - looks like I have to find a better way to troubleshoot!

5

I am glad that the penny has dropped.

As a matter of interest what are you using the pins for ?

Are all of the analogue pins used for analogue input or are some digital ?

Are any of the pins used for switch/button inputs ? I ask because it is possible to differentiate between multiple different switch inputs using just one analogue input

6

I'm building this Hardware h1.3 | Pulsar124 Wikia | Fandom

It's a focus stacking rail for macro photography. It uses 8 pins for the keypad, 4 pins for a Nokia 5110 display, a pin for shutter release, 3 pins for a big easy motor driver, a pin for limiting switches, and a pin for autofocus. All told that's 18 pins on an Uno that has 14 digital and 6 analog. It leaves me with pin 10 and I think one analog free.

Thanks!

7

Which of those requires analogue pins ?

Could you manage with a 3 by 4 keypad to save another pin ?

8

I could probably switch things around but there's no need. I was just verifying that it worked right by using the SerialPrint function. As it turns out that caused me problems that weren't there lol.

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