Understanding CodeCell Circuitry

CodeCell is a family of compact ESP32-based modules designed to pack sensors, power management, and connectivity into an incredibly small footprint, just 1.85 cm wide. 

Schematics, 3D models, and drawings for all four modules are available here.

Available Versions

ESP32 Microcontroller

Each CodeCell is built around a high-performance ESP32 module from Espressif:

• C3 / C3 Light: ESP32-C3-MINI-1-N4 - Single-core RISC-V CPU at 160 MHz, 4 MB Flash, Wi-Fi 4 + BLE 5.
• C6 / C6 Drive: ESP32-C6-MINI-1-H8 - RISC-V CPU + 802.11ax Wi-Fi 6 and BLE 5 + Zigbee, 8 MB Flash.

All models include a USB Serial/JTAG controller, allowing direct flashing and debugging via USB-C. The antenna is carefully positioned at the board’s edge to minimize noise and preserve strong wireless performance.

Power Management

Every CodeCell supports multiple power inputs for flexibility during prototyping and final integration:

• LiPo Battery Connector – for portable use and rechargeable operation.
• USB-C Port – for power, charging, serial and firmware upload.

Power management is handled by the BQ24232 chip with Dynamic Power-Path Management (DPPM), allowing the device to operate while charging. It supports up to 1500 mA output on battery and 450 mA via USB.

Charging follows three stages:

1. Pre-charge conditioning
2. Constant current
3. Constant voltage

By default, the LiPo charge current is set to 90 mA for the included 170 mAh battery. Users who wish to modify the charge current can do so by replacing 0402 resistor R12. However, this modification requires precise soldering skills, as 0402 components are extremely small. For further details, refer to the BQ24232 datasheet.

Voltage Regulation & Protection

A 3.3 V LDO (NCP177) provides up to 500 mA output with low dropout. 100 µF bulk capacitors and TVS diodes ensure smooth supply and ESD protection. This layout keeps CodeCell stable even when switching between battery and USB power.

GPIO & Pin Layout

Despite its small size, CodeCell has several GPIO and power pins for expansion:

• Power Pins: 5 V (USB input), 3.3 V output, and Ground (GND).
• I²C Pins: SDA and SCL (for sensors or as general GPIOs).
• GPIO Pins: 6 Input/Output pins with PWM support and ADC inputs (IO1–IO3).

Sensors and Motion Detection

• VCNL4040 Light + Proximity Sensor:
  • Measures ambient light and proximity up to 20 cm.
  • 16-bit resolution and integrated IRED for stable readings.
  • Fully supported by the CodeCell library for automatic setup and calibration.
• BNO085 9-Axis IMU (included on C3/C6/C6 Drive):
  • Accelerometer, gyroscope, and magnetometer fusion for motion tracking.
  • Provides orientation (roll, pitch, yaw), step counting, and tap detection, etc.

Motor Control (C6 Drive only)

The CodeCell C6 Drive adds a dual H-bridge motor driver, allowing direct control of two DC motors for robotics applications. Each driver channel is fully integrated on-board and controlled by dedicated GPIOs from the ESP32-C6.

For deeper insights, you can review the schematics and hardware files here.