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LCD1602 (I2C) on a Raspberry Pi 4B: Wiring & Python

Wire an I2C-backpack 16x2 LCD to a Raspberry Pi 4B using just 4 wires, and print text to it with Python — wiring, code, and common fixes.

Note: the LCD1602 (I2C) is a Premium-tier component in the simulator — you’ll need a Premium or VIP plan to use it there.

Try this directly in the free Raspberry Pi 4B simulator — no hardware or signup required. New to the GPIO header? Start with the interactive pinout guide.

What you’ll need

  • Raspberry Pi 4B
  • LCD1602 (I2C) — the I2C-backpack variant, not the parallel one

Step by step

  1. Drag Raspberry Pi 4B onto the Canvas.
  2. Drag LCD1602 (I2C) onto the Canvas.
  3. Hover over its pins to confirm labels: GND, VCC, SDA, SCL.
  4. Wire it up: GND → Pi's GND pin. VCC → Pi's 5V pin. SDA → Pi's SDA pin. SCL → Pi's SCL pin.
from RPLCD.i2c import CharLCD
lcd = CharLCD(i2c_expander='PCF8574', address=x27, port=1, cols=16, rows=2)
lcd.write_string("Hello ZOLB!")
  1. Click Start. The display only works while the simulation is running.

What “working correctly” looks like

  • Text appears on the simulated 16x2 display, matching what your script wrote — same visual result as the Parallel variant.

If something’s wrong

  • Import error, or nothing happens at all → the library path above may need adjusting to match what this component actually expects.
  • Nothing appears and the script runs without an error → this display always answers at I2C address 0x27, and it has no address setting. Use address=0x27 in your script.
  • The display stays blank → check its power. GND must reach a Pi GND pin and VCC must reach a Pi power pin, and the simulation must be running. An unpowered display ignores your script.
  • You left SDA or SCL unwired and the text still appears → the simulator does not check those two wires. Wire them anyway, because a real display needs them.
  • The text is gone after a restart → each Start begins with a clean, blank display. Your script has to write the text again.

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