matrix

A toy project to drive Sense Hat's LED matrix by using Go/JS.

Description

This project consists of 2 parts:

• A simple mobile front-end based on P5 that can modify the matrix data for 64 LEDs on Sense Hat.
• Golang based web server with REST APIs that accepts the configuration from the front-end and controls the LEDs via I2C.

An image can make more sense than the description above.

• The simple mobile web front-end has 64 dots that represent the 64 LEDs on Sense Hat.
• Users can choose which LEDs they want to control for the color with the 3 buttons such as All, Partial, and Single.
• The colors can be changed by the 3 sliders as well as the buttons below that can flip and turn the matrix.
• Lastly, there is an Apply button that sends the data to the RPI server (then the Go app takes the data and controls Sense Hat via I2C).

Here is a link to Youtube that shows its actual behavior.
https://youtu.be/xrmaou6DVRc

The readers can try this project with their RPI and Sense Hat.

Materials

Hardware

To properly reproduce this project, readers should have these hardwares:

• A host PC that has software to build this project
• A Raspberry Pi with a micro SD card that has more than 8 GB to store Raspbian stretch
• A Sense Hat
• Cables for power, network, and serial terminal

Software

The PC should have these tools:

• Go SDK (1.12 is the latest official version as of March 2019)
• VSCODE (+ Go and SFTP extensions)
• Web Browser (Chrome/Chromium)
• SSH/SFTP client
• Git client
• Should be connected to your router

The RPI should have these tools:

• OpenSSH server that has port opened as you want (not 22 though...)
• Should be connected to your router (Please note the IP address)

Steps to follow

1. clone this repo

First, clone this repo to the host.
Typically you can use the git command in Linux/Mac.

git clone https://github.com/bus710/matrix

2. open the project cloned

Open this repo with VSCODE.

code $PROJECT-ROOT/server

3. build the Go server for ARM processor

Assumingly the host has Go SDK and ready to build this repo.
If so, press CTRL + SHIFT + B, then VSCODE will show you a dialog to build for x64 or ARM (Please pick matrixARM).

4. Config SFTP extension (liximomo)

To push the matrixARM binary and the web contents files, a file (server/.vscode/sftp.json) should be generated (CTRL+SHIFT+P) and changed to point the RPI's IP address.

{
    "name": "upload to rpi",
    "host": "192.168.1.76",
    "protocol": "sftp",
    "port": 2222,
    "username": "pi",
    "remotePath": "/home/pi/",
    "uploadOnSave": false,
    "privateKeyPath": "~/.ssh/test",
    "passive": false,
    "interactiveAuth": false,
    "syncMode": "update"
}

The host and port should be updated regarding the RPI.

5. Generate a SSH key and push it to RPI

The host and RPI should share a SSH key to use the SFTP extension.

ssh-keygen -t rsa -b 2048 -v
ssh-copy-id -i .ssh/test.pub pi@192.168.1.76 -p 2222
ssh -p 2222 pi@192.168.1.76

If the key was well copied into RPI, the last command makes your terminal to log in to RPI without password.

6. Push the binary and web contents to RPI

From VSCODE,

• righ-click the matrixARM generated from the file explorer and click Upload.
• Repeat the same action for the public directory.

7. Run the Go server from RPI

From RPI's terminal, run below commands:

chmod 744 matrixARM
./matrixARM

8. Access RPI from Web brower of the host

From Web browser, access to http://192.168.1.76:8080.
(Pleae note that the address should be changed as your case).

9. Play with the app!

If you see a screen from your browser as same as the image example in the beginning, you are ready to play with that, enjoy!

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Disclaimer

This is just a toy project that cannot be used for safety/commercial products.   
The developer doesn't take any kind of (phsical, mental, and financial) responsibility.