node-red-contrib-raspi5-lcd-16x2

Node-RED node for Raspberry Pi 5 to write text to a 16x2 I²C LCD at address 0x38 (7-bit), using pure JavaScript via i2c-bus.

This targets I²C-controlled LCD modules (often ST7032/AIP31068-like), not PCF8574 backpacks (typically 0x27 / 0x3F).

Install

From the Node-RED user directory:

npm i node-red-contrib-raspi5-lcd-16x2

Restart Node-RED.

Prerequisites (Raspberry Pi)

1. Enable I²C in the OS.
2. Ensure your user can access /dev/i2c-1 (group i2c).

Check device address:

sudo i2cdetect -y 1
# you should see "38"

Node usage

Input

Send either:

• msg.payload as string → written to line 1 (line 2 stays empty)

or

• msg.payload as object:

{ "line1": "Hello", "line2": "Addr 0x38" }

Config

• I²C Bus (default 1)
• Address (default 0x38)
• Contrast (0-15) (default 8) — if the LCD is blank, try changing this.

Troubleshooting

If i2cdetect shows 38 but nothing appears:

• Try contrast values 0–15.
• Verify wiring (SDA/SCL + 3.3V/GND) and pull-ups.
• Some LCD modules need a slightly different init sequence.

License

MIT