led_panel_client's Introduction

LED panel client

Introduction

This will be a MicroPython client for the MQTT server. It’s going to run on a ESP8266 microcomputer using MicroPython. The LED panel will be composed of daisy-chained MAX7219 8 × 8 dot matrix LED arrays.

Currently it is just a playground to see, how to operate the LEDs. It displays a Space Invader image. The image switches to another when the on-board FLASH button.

Requirements

First, you need a ESP8266 microcomputer with a MicroPython firmware and a working serial connection from your computer. See documentation for further instructions.

Then, you need Python 3 with PIP. Install using brew install python.

To connect to the MicroPython’s REPL, you need picocom. Install using bres install picocom.

Instructions

General remark: In all further commands replace /dev/tty.wchusbserial1420 with the actual path to your COM device.

Installation

Install this package and its dependencies using setuptools:

$ pip install --process-dependency-links --editable .

Connect the microcomputer to the macrocomputer.

Put all the necessary files onto the PyBoard using this package’s command:

$ led_panel_client_put /dev/tty.wchusbserial1420

8 × 8 matrix connection

Connect the MAX7219 dot matrix to the microcomputer. The pin pairs are in the first two columns of the following table:

MAX7219	NodeMCU	Pin	SPI
VCC	3V
GND	G
DIN	D7	GPIO13	HMOSI (mosi)
CS	D8	GPIO15	GCS (cs)
CLK	D5	GPIO14	HSCLK (sck)

Run

Reset the microcomputer using the RST button on the board. This should load the main.py script.

For debugging, use picocom to connect to the PyBoard’s MicroPython REPL:

picocom -b 115200 /dev/tty.wchusbserial1420

Credit

Adafruit industries for the useful libraries
Nauč se Python! for the MicroPython workshop

Space invaders image found somewhere on the interwebz.

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led_panel_client's Issues

Load script doesn’t remove files

If boot.py is botched, the led_panel_client_put script will not remove it. Files are only overwritten, but they are not removed.

Connect to a WLAN on startup

The device should connect to a WLAN on startup, so it can receive messages. The SSID and password can be hard-coded for now. Let’s not focus on reconnecting now as it would require a ping-pong from the executive code to the WLAN handling module.