A wireless, open source, ESP32-based fingerprint sensor with optional NFC

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Chhavi is a tiny, wireless, touch-capacitive fingerprint sensor with high-end security capabilities, support for ultra-low-power operation, and optional NFC connectivity. Its open source firmware is fully compatible with Arduino IDE. Powered by ESP32 and equipped with an FPC BM-Lite fingerprint sensor, by Fingerprints, Chhavi gives you and your projects access to the superior biometric hardware found in many smartphones. Unlike optical fingerprint sensors, which are large and power hungry, this capacitive biometric sensor is tiny, accurate, and power efficient.

During our design process, we determined that NFC communication is a powerful feature for many of the same applications that might require a high-quality fingerprint sensor, yet we could not find a major ESP32-powered NFC controller. So we built one into Chhavi as an optional feature. We also added an optional battery to simplify installation and to facilitate mobile deployments. The result is a tiny device with a cutting-edge fingerprint reader, Wi-Fi and Bluetooth capability, and support for NFC and battery power if you need them.

Perfect for Physical Security, Device Authentication, Personnel Management, and More

Whether it’s drawing power from a battery or plugged in through USB, Chhavi is well suited to all kinds of fingerprint-sensor applications: signing in to a desktop computer, unlocking a password manager, implementing door locks and other physical security controls, powering attendance or personnel-management systems, or adding biometric authentication to a DIY hardware project – to name just a few examples.

Wireless, Battery-Powered, Biometric Locking Mechanisms

Personnel Management & Data Retrieval

Chhavi comes with an open source library that makes it easy to program using Arduino IDE. And because it includes a built-in USB-to-UART adapter, you can program the ESP32 module right out of the box. Do you prefer working with Espressif’s ESP-IDF framework? Don’t worry, we’re developing a library for that as well!

Despite its tiny, 26 x 26 x 9 mm size, Chhavi is packed full of quality-of-life features as well. It includes a vibration motor, for example, that provides immediate haptic feedback in the event of a successful or unsuccessful fingerprint scan (or that you can re-purpose for other applications as needed). In addition to an MCU reset button, Chhavi also comes with an intuitive on/off switch that allows you to preserve power when it’s running off a battery. (And if you don’t need this feature—if it’s drawing power through USB, for example—you can use that interface as a GPIO instead.)

Add to the above a modular design, an IP7X sensor panel with remarkable physical durability, robust power-management circuitry, longevity estimated at 10 million scans, a built-in 3D antenna…and the list goes on.

Features & Specifications

Physical Features



Power Management

Fingerprint Sensor


NFC Specifications & RF Protocols

¹ ISO/IEC 18092 (NFCIP-1) edition, 2013-03-15. This is similar to Ecma 340
² ISO/IEC 15693 part 2: 2nd edition (2006-12-15), part 3: 1st edition (2001-04-01)
³ ISO/IEC 14443 parts 2: 2001 COR 1 2007 (2007-11-01), part 3: 2001 COR 1 2006 (2006-09-01) and part 4: 2nd edition 2008 (2008-07-15)
NFC Forum Device Requirements V1.3
ISO/IEC 15693 part 2: 2nd edition (2006-12-15), part 3: 1st edition (2001-04-01)

Click to enlarge


ChhaviGT521F52 Optical SensorR301T Fingerprint ModuleSeeedStudio Grove
Capacitive TouchYes No No Yes
Low PowerYes No No Yes
Wi-FiYes No No No
BLEYes No No No
NFCOptional PN7150 No No No
Battery PoweredOptional No No No
Open-SourceYes No No No
Works With ArduinoYes Can be made to work Can be made to work Yes
Main ControllerESP32 None (needs host) None (needs host) None (needs host)
False-Acceptance Rate1/500000 1 / 10000 1 / 10000 1/20000
Verification Time0.4 seconds 1.5 seconds 0.3 seconds 0.34 seconds

Support & Documentation

Our open source files are available in our public GitHub repository. You can find more information about Chhavi’s biometric sensor on Fingerprint‘s website. You can reach us by way of the Ask a technical question link below. (Please do!)

Additional Resources:

In the Press

Biometric Update

"The new Chhavi device is built on an Espressif ESP32 microcontroller and open source code, and features better biometric performance with lower power requirements than optical sensors..." logo

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Produced by Vicharak in Surat, India.

Sold and shipped by Crowd Supply.

Chhavi - Fingerprint Sensor & Battery

Chhavi with an FPC BM-Lite fingerprint sensor, a 200 MAh battery, and a 3D-printed stand.

$65 $8 US Shipping / $18 Worldwide

Chhavi - Fingerprint Sensor, NFC, and Battery

Chhavi with an FPC BM-Lite fingerprint sensor, a NFC controller, an antenna module, a 200n MAh battery, and a 3D-printed stand.

$75 $8 US Shipping / $18 Worldwide

About the Team


Surat, India  ·   Vicharak_In  ·   vicharak-in  ·

We are pioneering reconfigurable computing in order to address complex challenges more quickly and easily. Our unique hardware seeks to redefine existing architectures and capabilities so we can move beyond century-old notions of computing.

Akshar Vastarpara
Team Lead
Harit Shukla
Hardware Developer
Jagrutkumar Vaghela
Hardware Developer

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