Node.js Script and Circuit for NXTP7X962M LED Signs

Control an LED sign with Node.js thru the serial port.

Requirements

• Node.js
• Yarn or npm
• A 3.3V TTL serial port. Tested with CP2102 module.

Instructions

1. Edit serial port in index.js if not ttyUSB0.
2. Run yarn or npm install to install dependencies.
3. Run yarn start or npm start to run. Puts "HELLO WORLD!!!" on the sign.

Circuit

• Connects a TTL 3.3v serial port to the LED sign's J1708 port, e.g.:
  • Raspberry Pis
  • 3.3v Arduinos
  • USB to 3.3V TTL serial adapters. Tested with CP2102 module.
• If you just want to write to the sign, i.e. you don't care about receiving from the sign, the circuit is very simple: one 680 ohm resistor from TXD to A, and one 680 ohm resistor from +3.3V to B.
• Drives one LED sign. To daisy chain you need to modify the resistor divider, i.e. the ones with asterisks.
• circuitjs.txt can be imported at https://www.falstad.com/circuit/