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I am really new to this Arduino stuff. I can't figure out one of my problems on my own.

I am using this 2.4 TFT display shield on an Arduino Uno. It works fine so far: I have coded a little sketch for it that displays a start button and after tapping that it shows random colors.

Now I would like to connect a circuit with jumper cables that are used as sensors. When I touch one of the jumper cables the light connected will turn on.

The problem I have now is that this specific circuit is using an other Arduino because my first Arduino is already 'full' because the TFT shield is taking up all pins.

How can I resolve my problem? Is it possible to Stack Arduinos? Is it possible to connect those Arduinos somehow? Thanks in advance!

  • Have you tried googling "communication between two arduinos"? what did you learn? – Delta_G Jun 10 '18 at 0:17
  • I suggest adding your circuit and program. – sa_leinad Jun 10 '18 at 7:47
  • As I mentioned my problem is mainly that my arduino is fully used, I guess, by my tft shield. – Gijsberts Jun 10 '18 at 11:56
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As I can read your link, the shield is using D2-D8 and A0-A3, leaving some pins unused. So some Arduino pins are still free to use, just the shield is in the way to get connected there.

So there are some possible ways:

  • brutally solder some wires to the shield unused pins from front side and use that wires to connect where you want (sensors, breadboard, universal PCB, ...)
  • brutally solder some wires to arduino bottom on unused pins, then continue as mentioned
  • create intermediate shield (there are many, which allow you connect to arduinou on bottom and stack antother shield on top, draw your wires from there (and maybe even put some circuities on the middle shield, if you want (something like this https://www.aliexpress.com/item/UNO-Prototype-DIY-shield-kit-for-Arduino-UNO-Universal-Extend-Board-UM-UNO/32555004112.html or any "arduino universal shield"

https://www.indiegogo.com/projects/ardushield-most-universal-shield-for-arduino-ever#/ works excelently across arduinos and other shields/breadboards ...

or anything along this lines ... http://shieldlist.org/sunhayato/universal


As for other part of question - It is possible to connect more arduinos, there are so much different ways, that it is hard to write here all - choose one, that would suit you best. (anyway you would need some access to some pins anyway )

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Ok, your problem seems to be that you have run out of pins. Currently you are using an Arduino Uno. I would go out and buy an Arduino Mega.

Alternatively you could use the analog inputs as digital inputs.

Arduino Uno
Digital I/O Pins 14 (of which 6 provide PWM output)
Flash Memory 32 KB (ATmega328P) of which 0.5 KB used by bootloader

Arduino Mega
Digital I/O Pins 54 (of which 15 provide PWM output)
Flash Memory 256 KB of which 8 KB used by bootloader

  • Alright. Is the arduino mega working the same way as the arduino uno except it has more power and pins? – Gijsberts Jun 10 '18 at 11:58
  • Pretty much! - I'll add links to my answer. – sa_leinad Jun 11 '18 at 0:52

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