NodeMCU MAX7219

A NodeMCU library to write to MAX7219 8x8 matrix displays and 7-Segment modules using SPI

http://frightanic.com/iot/max7219-library-nodemcu-making/

Hint: The module (not the logic) needs to be powered by 5V otherwise it can lead to undefined behavior.

max7219 = require("max7219")
max7219.setup({debug = true, numberOfModules = 4, slaveSelectPin = 8})
max7219.write({
    { 0x20, 0x74, 0x54, 0x54, 0x3C, 0x78, 0x40, 0x00 },
    { 0x41, 0x7F, 0x3F, 0x48, 0x48, 0x78, 0x30, 0x00 },
    { 0x38, 0x7C, 0x44, 0x44, 0x6C, 0x28, 0x00, 0x00 },
    { 0x30, 0x78, 0x48, 0x49, 0x3F, 0x7F, 0x40, 0x00 }
  }, { rotate = "left" })
  
-- Clear the module:
max7219.clear()
  
-- Turn the module off without loosing the text:
max7219.shutdown(true)

-- Turn the module on:
max7219.shutdown(false)

-- Set minimum brightness:
max7219.setIntensity(0)

-- Set maximum brightness:
max7219.setIntensity(15)

-- Write to a 7-Segment module (these characters are not supported: kmwxKMWX):
max7219.write7segment("HELLO")

-- The decimal point is supported as well:
max7219.write7segment("32.5°C")

-- Write to a 7-Segment module and right-align the text:
max7219.write7segment("HELLO", true)

All missing features are tracked as issues on GitHub.