TCA9534 I2C GPIO Expander
Add 8 extra digital I/O pins over I2C. Each pin can be independently configured as input or output.
Say it to PAL
“Blink the light on pin 0.”
The code PAL writes
p.write('qwiic-gpio', 'set_mode', { pin: 0, mode: 'output' });
p.write('qwiic-gpio', 'set_pin', { pin: 0, value: 1 });
await p.sleep(1000);
p.write('qwiic-gpio', 'set_pin', { pin: 0, value: 0 });“Switch pin 3 on and off every 2 seconds.”
The code PAL writes
p.write('qwiic-gpio', 'set_mode', { pin: 3, mode: 'output' });
p.every(2000, () => {
p.write('qwiic-gpio', 'toggle_pin', { pin: 3 });
});
await p.waitUntilStopped();When to pick it
Need extra digital I/O pins. Best for LEDs, buttons, or low-speed digital signals.
Good to know
- Max sink/source current is 25mA per pin — cannot drive motors directly.
About it
The TCA9534 is an 8-bit I2C GPIO expander that adds 8 general-purpose digital pins. Each pin is independently configurable as input or output with polarity inversion. Up to 8 expanders can be chained (addresses 0x20-0x27) for up to 64 extra I/O pins. Ideal for expanding GPIO when the Pi's pins are limited.
Where to buy
Facts
Tested
Its driver works. We have not signed it off on a real board yet.
I2C address
0x27, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26
The TCA9534 I2C GPIO Expander answers at I2C address 0x27. A jumper or pin moves it to 0x20 or 0x21 or 0x22 or 0x23 or 0x24 or 0x25 or 0x26.
Current
1 mA
The catalog lists a typical draw of 1 mA for the GPIO Expander, copied from the maker’s description and not measured by Palpable.
Board size
60.96 × 38.1 mm
The GPIO Expander board measures 60.96 × 38.1 mm and stands 14.6 mm tall with its parts. It has 4 mounting holes. These dimensions are from the maker’s mechanical drawing.
Free to reuse
Every fact here is open data under CC BY 4.0. Copy it into your own docs or code, and credit Palpable. Download it
This record was last changed on September 24, 2026.