Presence Detection
LD2410C mmWave radar wakes the device when a user sits at the desk and enables smart sleep behavior.
Overview
The device senses presence, reacts to ambient conditions, and provides feedback using display, RGB, audio, and haptics.
Visual Feedback
WS2812B LEDs and a TFT display communicate states like focus mode, music visualizer, alerts, and low battery.
Phone Notifications
BLE link with a Flutter companion app delivers notifications and mode changes to the device in real time.
Parts & What They Do
Every component explained — what it is, what it does in this project, and its approximate cost in Indian rupees.
Microcontroller
XIAO ESP32-S3
The brain. Runs all code, handles Wi-Fi/BLE, I2C, SPI, UART, I2S, ADC, and deep sleep. Has 8MB PSRAM — must be enabled.
₹680
Core
Display
ST7789 1.69" TFT
240×280 color screen connected via SPI. Shows faces, clock, music visualizer, and notification text.
₹350
Output
RGB LEDs
WS2812B (8 LEDs)
Individually addressable color LEDs. React to sound, mode, and notifications. Needs a 5V level shifter to drive reliably.
₹100
Output
Presence Radar
LD2410C (UART)
mmWave radar detects if a person is sitting at the desk — even when still. Sends UART data at 256000 baud.
₹400
Sensor
Motion Sensor
MPU6050 (GY-521)
Accelerometer + gyroscope over I2C. Detects taps, tilts, and motion. Can trigger events or detect desk knocks.
₹120
Sensor
Light Sensor
BH1750 (GY-302)
Measures ambient light in lux over I2C. Automatically dims LEDs and display in dark rooms, brightens in daylight.
₹140
Sensor
Touch Sensor
TTP223 Capacitive
Single-touch capacitive pad. Tap to cycle modes, dismiss notifications, or toggle display — no moving parts.
₹20
Input
Microphone
INMP441 I2S
Digital I2S mic. Picks up claps, ambient volume, and sound patterns. Used for music visualizer and clap-to-wake.
₹200
Sensor
Audio Amplifier
PAM8403 Class-D
Drives the speaker via PWM signal from GPIO6. Plays alert tones, melodies, and beeps. Clean Class-D output.
₹60
Output
Speaker
8Ω 2W
Small speaker connected to PAM8403. Salvageable from old toys/earphones or bought new for ₹100.
₹100
Output
Vibration Motor
3V Coin Type
Haptic feedback for alerts and notifications. Driven by a 2N2222 NPN transistor switch from GPIO14.
₹40
Output
LiPo Battery
3.7V 1000mAh (502030)
Main power source. Rechargeable lithium polymer cell. Size 502030 fits in a compact enclosure.
₹150
Power
Charger
TP4056 USB-C
Charges the LiPo via USB-C safely. Get the version with protection circuit built in (overcharge / overdischarge guard).
₹25
Power
Boost Converter
MT3608 Adjustable
Steps up 3.7V battery to stable 5.0V for the ESP32, LEDs, and display. Set with trim pot + multimeter.
₹45
Power
Level Shifter
74AHCT125 (4-ch)
Converts 3.3V data signal to 5V for WS2812B LEDs. Without this, LEDs glitch and flicker. NOT optional.
₹100
Logic
Passives Kit
Resistors, Caps, Transistor, Diode
330Ω for LED data, 1kΩ for transistor base, 100k/100k divider for battery ADC, 1N5819 diode, 2N2222 NPN transistor.
₹140
Electronics
Breadboard + Wires
830pt + Jumper Set
For prototyping each phase before soldering. Essential for testing and debugging without permanent connections.
₹450
Build
Perfboard
5×7 cm
For the final soldered build. Replace the breadboard with this once all phases test correctly.
₹50
Build
Illustrated content pages
Explore dedicated pages with better structure for features, stages, and complete build instructions.
Features
Detailed capability breakdown and functional blocks.
Stages
Build flow split into clear project stages from setup to integration.
Guide & Steps
Actionable, sequential steps for wiring, firmware, validation, and finishing.