{"product_id":"mpr121-capacitive-touch-sensor-module-12-key-i2c-controller","title":"MPR121 Capacitive Touch Sensor Module – 12-Key I2C Controller","description":"\u003ch1\u003eMPR121 Capacitive Touch Sensor Controller Module\u003c\/h1\u003e\n\u003cp\u003eThe 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.\u003c\/p\u003e\n\n\u003ch2\u003eKey Specifications\u003c\/h2\u003e\n\u003ctable\u003e\n  \u003cthead\u003e\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003eValue\u003c\/th\u003e\n\u003c\/tr\u003e\u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n\u003ctd\u003eOperating Voltage\u003c\/td\u003e\n\u003ctd\u003e2.5V – 3.6V (3.3V typical)\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eTouch Inputs\u003c\/td\u003e\n\u003ctd\u003e12 capacitive electrodes\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eCommunication\u003c\/td\u003e\n\u003ctd\u003eI2C, up to 400kHz, 4 selectable addresses\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eOperating Current\u003c\/td\u003e\n\u003ctd\u003e~8 µA idle, ~20 µA scanning all channels\u003c\/td\u003e\n\u003c\/tr\u003e\n    \u003ctr\u003e\n\u003ctd\u003eProximity Detection\u003c\/td\u003e\n\u003ctd\u003eUp to ~30 mm range, adjustable sensitivity\u003c\/td\u003e\n\u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003ch2\u003eWhat You Can Build With This\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\u003ca href=\"\/products\/capacitive-touch-keyboard-kit\"\u003eCustom 12-key capacitive touch keyboard or numpad\u003c\/a\u003e\u003c\/li\u003e\n  \u003cli\u003eTouch-sensitive musical instrument (MIDI controller)\u003c\/li\u003e\n  \u003cli\u003eInteractive wall panel or light switch\u003c\/li\u003e\n  \u003cli\u003eProximity-activated lamp or alarm\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eCompatibility\u003c\/h2\u003e\n\u003cp\u003eWorks 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.\u003c\/p\u003e\n\n\u003ch2\u003eWiring Notes\u003c\/h2\u003e\n\u003cp\u003eConnect 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.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Buy from Compoden\u003c\/h2\u003e\n\u003cp\u003eEvery 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.\u003c\/p\u003e\n\n\u003cdetails\u003e\u003csummary\u003eIs this compatible with Arduino Uno?\u003c\/summary\u003e\u003cp\u003eYes, 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.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eHow many touch electrodes can I use?\u003c\/summary\u003e\u003cp\u003eThe 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.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdetails\u003e\u003csummary\u003eDoes it need external components?\u003c\/summary\u003e\u003cp\u003eNo 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.\u003c\/p\u003e\u003c\/details\u003e\n\u003cdiv class=\"compoden-handoff\" style=\"margin-top:24px;padding:16px;background:#f0f4ff;border-left:4px solid #2B4D8F;border-radius:4px;\"\u003e\n  \u003cp style=\"margin:0 0 6px 0;font-weight:600;color:#1A3560;\"\u003e📦 Free Setup Handoff Document Included\u003c\/p\u003e\n  \u003cp style=\"margin:0;font-size:0.95em;color:#333;\"\u003eEvery 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.\u003c\/p\u003e\n\u003c\/div\u003e\n","brand":"Compoden","offers":[{"title":"Default Title","offer_id":53445125833069,"sku":"CDN-0688","price":120.0,"currency_code":"INR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0999\/3997\/5533\/files\/image_1_721c8fbb-104e-4250-ba1b-71a7f451ee42.jpg?v=1781513443","url":"https:\/\/compoden.com\/products\/mpr121-capacitive-touch-sensor-module-12-key-i2c-controller","provider":"Compoden","version":"1.0","type":"link"}