LCD
16×2 LCD (I2C backpack)
16×2 character LCD with a PCF8574 I2C backpack soldered on — turns the classic 16-pin HD44780 parallel interface into 2 wires.
LCD1602 + PCF8574 · Generic (HD44780-compatible glass + PCF8574 backpack)
🍌 Simulates in-browserOverview
A standard HD44780-compatible 16×2 character LCD wired to a PCF8574 I2C GPIO-expander backpack. The PCF8574 IC itself supports 2.5–6V; the assembled LCD, backlight, contrast circuit and I2C pull-up rail vary by backpack vendor. Many modules are intended to run at 5V and pull SDA/SCL up to that rail, which is unsafe for a 3.3V-only MCU unless those pull-ups are level-shifted or moved to 3.3V.
Wiring tip: SDA/SCL, commonly 0x27 or 0x3F — check the backpack supply and pull-up rail before connecting a 3.3V MCU
Pins & wiring
16×2 LCD (I2C backpack)
Module
Logical order only — confirm the physical package drawing.
All pins
Hover · click to selectSelected pin
gnd
- Direction
- Passive
Full pin table
| Name | Role | Direction |
|---|---|---|
| Ground | Passive | |
| Power | Power | |
| I2C | Open-drain | |
| I2C | Open-drain |
Wiring examples
5V host (Arduino Uno) — the natural match
arduino-uno pinout →| 16×2 LCD (I2C backpack) pin | Connects to | Note |
|---|---|---|
| VCC | 5V | — |
| GND | GND | — |
| SDA | A4 | — |
| SCL | A5 | — |
- No level shifting needed — both the Uno and this backpack run 5V logic.
3.3V host (ESP32) — inspect the backpack pull-ups
esp32-devkit-v1 pinout →| 16×2 LCD (I2C backpack) pin | Connects to | Note |
|---|---|---|
| VCC | VIN | Many assembled LCD modules need 5V for the LCD/backlight; confirm yours. |
| GND | GND | — |
| SDA | GPIO21 | Through a level shifter, not direct. |
| SCL | GPIO22 | Through a level shifter, not direct. |
You also need
- Required level-shifter between SDA/SCL and GPIO21/GPIO22 — Required when the backpack's I2C pull-ups rise to 5V. An alternative is removing/isolating those pull-ups and adding suitable pull-ups to 3.3V, after checking PCF8574 VIH at the chosen VCC.
- Measure or trace the SDA/SCL pull-up rail. If it is 5V, do not wire it directly to ESP32 GPIOs.
Specifications
Footprint
No independently verified physical footprint is on file for this part yet.
Alternatives
Upgrades
Strictly better on the headline spec, but expect to touch firmware or wiring to actually use the difference.
Graphics-capable at a similar four-wire I2C connection cost, but it needs a display-driver library swap. Generic SSD1306 breakout supply and pull-up arrangements vary, so verify the exact module before connecting 5V or a 3.3V host.
Compare with 16×2 LCD (I2C backpack)- Technology: lcd → oled
- Operating Voltage: vendor-specific 5V LCD/backpack → varies by SSD1306 breakout
Documents
Datasheets
- HD44780U LCD Controller DatasheetHitachi
- PCF8574 I2C I/O Expander DatasheetTexas Instruments
Frequently asked questions
What voltage does the 16×2 LCD (I2C backpack) run at?
Banana Board does not have a verified operating voltage on file for the 16×2 LCD (I2C backpack) yet — check the datasheet in Documents before wiring it up.
How many pins does the 16×2 LCD (I2C backpack) have?
The 16×2 LCD (I2C backpack) has 4 pins, communicating over I2C. See the full pinout table in Pins & wiring for each pin's role.
Can I simulate the 16×2 LCD (I2C backpack) before ordering hardware?
Yes — the 16×2 LCD (I2C backpack) has a live in-browser simulation model, so you can exercise the circuit before ordering any hardware.
Where is the 16×2 LCD (I2C backpack) datasheet?
Linked in the Documents section on this page, and cited on every spec that came from it.
Related references
Build it, do not just look it up
Describe your circuit in one sentence and Banana Board wires it to these exact pins, validates it, and lays out a fab-ready PCB.