PCF8574 I/O Expander
Simple 8-bit I2C expander used in LCD backpacks and button panels.
AI Ready Overview
Quick Summary
PCF8574 is a i/o expander commonly used in FYP and embedded projects. It is best for lcd backpack and button input panel, with wiring and testing planned around Arduino, ESP32, LCD 16x2.
Difficulty
Beginner
Time Required
1-3 days for basic wiring and sample code; 1 week if used inside a complete FYP prototype
Cost
RM4-RM12 module range in Malaysia; full project cost depends on scope.
Components
PCF8574, Arduino, ESP32, LCD 16x2
Overview
What is PCF8574?
PCF8574 provides simple I/O expansion over I2C. It is widely used in 16x2 LCD I2C backpacks and can also read buttons or drive small logic signals.
Engineering Reference
Quick Specs
| Operating Voltage | 3.3V / 5V |
|---|---|
| Interface | I2C, GPIO |
| Difficulty | Beginner |
| Typical Malaysia Price | RM4-RM12 |
| Best For | LCD backpack, Button input panel |
Real Usage Notes
Suitable / Not Suitable
Suitable for
- ✓ LCD backpack
- ✓ Button input panel
- ✓ Simple GPIO expansion
Not suitable for
- ✕ High-current output
- ✕ Precise PWM
- ✕ High-speed signal control
Build Planning
Difficulty
PCF8574 is rated Beginner. Plan around 1-3 days for basic wiring and sample code; 1 week if used inside a complete fyp prototypedepending on wiring, libraries, calibration, dashboard/app integration and testing evidence.
Build Planning
Time Required
1-3 days for basic wiring and sample code; 1 week if used inside a complete FYP prototype
Malaysia Price Guidance
Cost
Typical module price range: RM4-RM12. This is component guidance only; a complete FYP cost depends on controller, sensors, casing, display, app/dashboard, documentation and timeline.
Connections
Connection overview
Power
Use only a supply supported by the exact board or module variant. Common listings for this part mention 3.3V or 5V.
Ground
Connect a common ground between the controller, module and any external supply.
Primary interface
Plan for I2C / GPIO; confirm the exact terminal names in the manufacturer documentation.
Variant-specific connections
Connector names and optional pins can differ between breakout-board revisions.
Platform Notes
Wiring Guides
PCF8574 with Arduino / ESP32
This is a planning overview, not a board-specific pin map. Confirm the exact module revision, supply limits and I2C / GPIO terminals in its datasheet before wiring. Use suitable level shifting when logic voltages differ.
| Power | Confirm against the exact board; listed variants commonly use 3.3V / 5V |
|---|---|
| Ground | Common ground with the controller |
| Interface | I2C, GPIO (exact pins vary by module) |
Fix Common Problems
Troubleshooting
Troubleshooting
Common Mistakes
FYP Ideas Using PCF8574
Related Projects
Compare Options
Alternative Components
Student Questions
FAQ
Is PCF8574 good for FYP projects?
Yes, PCF8574 is suitable for FYP work when the project matches its limits: LCD backpack and Button input panel.
What is the most common PCF8574 mistake?
Wrong I2C address