MPR121 Capacitive Touch Sensor Module – 12-Key I2C Controller
MPR121 Capacitive Touch Sensor Controller Module
The MPR121 is a dedicated capacitive touch controller with 12 electrode channels, communicating over I2C. It enables touch and proximity detection for building custom keypads, interactive surfaces, and wearable interfaces. No external components are required for basic touch sensing.
Key Specifications
| Specification | Value |
|---|---|
| Operating Voltage | 2.5V – 3.6V (3.3V typical) |
| Touch Inputs | 12 capacitive electrodes |
| Communication | I2C, up to 400kHz, 4 selectable addresses |
| Operating Current | ~8 µA idle, ~20 µA scanning all channels |
| Proximity Detection | Up to ~30 mm range, adjustable sensitivity |
What You Can Build With This
- Custom 12-key capacitive touch keyboard or numpad
- Touch-sensitive musical instrument (MIDI controller)
- Interactive wall panel or light switch
- Proximity-activated lamp or alarm
Compatibility
Works with any microcontroller that supports 3.3V I2C, including ESP32, ESP8266, Raspberry Pi, STM32, and Arduino boards with logic level conversion. The module’s VCC and logic levels are 3.3V; when using 5V systems like Arduino Uno, add a bidirectional level shifter on SDA and SCL lines.
Wiring Notes
Connect VCC to 3.3V, GND to ground, SDA and SCL to your microcontroller’s I2C pins. The ADDR pin sets the I2C address; leave unconnected for default 0x5A. Touch electrodes can be copper tape, conductive thread, or PCB traces. Keep electrode leads short to minimize noise pickup.
Why Buy from Compoden
Every component is sourced from verified suppliers and tested for compatibility before listing. We've spent 10 years building projects for makers, schools, and institutions across India. Ships from Bengaluru in 3-5 days. If defective on arrival, replace within 7 days.
Is this compatible with Arduino Uno?
Yes, but the MPR121 module operates at 3.3V logic while Arduino Uno uses 5V I2C. You must insert a bidirectional level shifter on the SDA and SCL lines, or choose a 3.3V Arduino like the Pro Mini 3.3V.
How many touch electrodes can I use?
The MPR121 supports up to 12 capacitive touch electrodes. You can use fewer if your project needs only a few; unused channels are automatically disabled to save power.
Does it need external components?
No external resistors or capacitors are required for basic touch sensing. The module includes onboard I2C pull-up resistors and decoupling; simply connect electrodes and power.
📦 Free Setup Handoff Document Included
Every Compoden order includes a free setup handoff document — step-by-step instructions to get your component working within minutes. Download it via QR code on your package. The handoff document is also trained to help you troubleshoot the majority of problems.
Ask Soldr above what you can build with this — it knows every Compoden kit this part appears in.
Shipping Information
- Prepaid Orders: ₹75 for orders up to ₹999, FREE shipping above ₹999
- COD Orders: ₹125 shipping + ₹50 COD fee = ₹175 total
- Delivery Timeline: Dispatch in 1-2 days, delivery in 2-7 days depending on location
Returns & Warranty
- 7-Day Return: Manufacturing defects only (approval required)
- Warranty: 7 days from delivery
- Non-Returnable: Batteries, consumables, cut wires, clearance items