3 button and 3 LED for Tricorder

I'm doing something close to Picorder - Squared Wave

Getting wires from the SBC to screen enclosure is not going to be easy. Old school way would be 7 wires, that means 6 pins (pulse common)

What's the right way of doing this? Has to be something with less than 7 wires

Read the pinned post re 'How to get the most from the forum'. Right now, we have nothing to work with (I don't chase unknown links)

You don't need the link to answer the question, it just add context.

3 LED and 3 buttons means 7 wires... is there a way to do it with fewer wires?
A keyboard does it with 4 wires... I don't know how... would that idea work?
If yes, can someone tell what to google, I don't know the words?
If not, what would?

Yes, it is possible.
There are several ways to do it.
I will list at least 2 ways.
For example, several (6 or more) buttons can be "interconnected" with a controller with only 2 wires. Using analog ports.
You can also interconnect buttons, LEDs, etc. with only 2 wires, using 1-Wire technology.

Make a drawing (or sketch) of your project, even freehand, so that we can better understand your needs and help you better.

Been quite a few years sense I did drafting.

BTW, this is running off an 18650 with a 5v 2a board. SBC is eating up 1a, and screen needs some too


This is the whole (original) project.
I'm not using the SenseHAT, and I didn't get the same screen (discontinued)

Read four keys with three I/O - PCB with IR and 4 Buttons - #37 by Claudio_FF (post #38). You could just omit one of the keys.

Read up on charlieplexing for the LEDs.

A B C Function
L - - Read B1
- L - Read B2
- - L Read B3
H L - ON-LD1
- H L ON-LD2
L - H ON-LD3

"-" are Hi-Z outputs

You could use a PFC8574 chip. This will require 4 wires.

But for the best advice, you are going to have to give us more details of the rest of your circuit. How does the screen connect to the SBC for example? Many use SPI interface. In that case you could use a MCP23S08 chip which will require only 1 more wire because it can share other wires with the display.

J2 is the SPI for screen and touch. Don't need the card reader, not sure why it's on there.

I'll be using all 14 pins for the display, other than the 3 buttons there's no input ...so, sort of need the touch screen

An improvement in the level of detail. But still not great.

Have you read the forum guide in the sticky post at the top of most forum categories?

What we need is a schematic (not a wiring diagram) showing how this display and the other components are wired to the Arduino/ESP.

Assumably it's going to be the standard pin out

LCD - RPi
SDO(MISO) - MISO/GPIO9, pin21 (common)
LED - 5V through 1k resistor, pin 2 (common)
SCK - CLK/GPIO11, pin23 (common)
SDI(MOSI) - MOSI/GPIO10, pin19 (common)
D/C - GPIO24, pin18
RESET - GPIO25, pin22
CS - CE0/GPIO8, pin24
GND - GND, pin 6 (common)
VCC - 3.3V, pin 1 (common)

I'm having problems find how to get the touch pinout. Got a month to figure it out


Not good with Fritzing, but this might help?
Color is random, so is not be standard