Is 36 inputs possible?

Can an Arduino handle 36 inputs?

I want to make a Learning (?) Board for my son that has 36 individual buttons (A-Z and 0-9) which will play unique and specific *.mp3 files (recordings of mom or dad saying each letter/number). Is this possible?

I would imagine that the easy answer is to use several Arduinos, but I'm also looking to use what I already have without the expense of buying more boards.

Thanks for any advice you can give!

We don’t know what Arduino you have.

You can use i/o expansion I.C.s

You can use a Mega.

For an Uno, you can use I2C exanders (MCP23008, MCP23017*, PCF8574) or parallel in-serial out shift registers (74HC165) get over 100 inputs.

*or the SPI MCP23s17.

You can connect the buttons as a matrix, 6 lines by 6 rows. Usual technic for some keyboards.

We don’t know what Arduino you have.

True, thanks... I have the UNO. Circa 2011 (?) It's old.


Easiest and probably cheapest these days is an Arduino Mega which has 48 digital signal pins.

To make it not-as-insane to wire, get a Mega Sensor Shield (LINK)

and use ribbon cables to connect to your many switches. See THIS PAGE

Like these:

Then if needed cut of the ends and solder to you switches..

You can connect the buttons as a matrix, 6 lines by 6 rows. Usual technic for some keyboards.

I thought about this, but (and please forgive the ignorance) wouldn't that matrix result in every line being grounded to itself?

Here is a playground page on the basics of matrix keypads.

Actually, don’t fart around with expansion chips.

Terry offers very reasonable boards.
Mega @ $18.00
Digital I/O Pins 54 (of which 14 provide PWM output)
Analog Input Pins 16


Where in the World are you?

If you promise to write your whole project up and include photos of The Kid using it so I can put it on https://ArduinoInfo.Info I'll send you a Mega and Sensor Shield...

I have 14 grandchildren and am a sucker for KidsFunStuff :slight_smile:

The solution suggested by groundFungus needs 6 output and 6 inputs, a technicaly easy solution.

Multiple buttons with resistor ladders on analogue inputs is another solution.
But a keypad matrix should be easier.