Carl Bugeja Introduces Microbot's CodeCell: Tiny MCU Board to Power Creative (Tiny) Robots

In his latest video, Carl Bugeja introduces Microbot's newest creation: the CodeCell, a compact yet powerful brain for small robots. This ESP32-powered board, equipped with a range of sensors, is not just for serious tasks — it can also entertain with its ability to tell jokes!

Microbots chose the Espressif ESP32-C3 Mini system-on-chip (SoC) to power CodeCell. This SoC has a single RISC-V core with built-in memories and a radio that supports 2.4 GHz Wi-Fi, Bluetooth, and Bluetooth Low Energy (LE). Users program the board via USB.

The highly optimized 18 x 18 millimeter printed circuit board (PCB) includes several other components. Microbots included a LiPo charge controller, a 3.3 volt regular, addressable RGB LED (like a NeoPixel), an IR Light Sensor, and an optional nine-axis Inertial Measurement Unit.

Using the onboard LiPo controller, CodeCell can drive small DC motors, actuators, and loads appropriate for a small robot. Bugeja demonstrated its capability by controlling and driving the LEDs from the Mini-Sphere project.

The Vishay VCNL4040 IR Light/Proximity Sensor gives CodeCell several capabilities. It can detect depth gestures and the proximity of an object up to 20 centimeters away. A small robot could use these features to detect objects and avoid collisions.

CodeCell can ship with an optional CEVA BNO085 9-axis motion sensor. This internal measurement unit (IMU) has an accelerometer, gyroscope, and magnetometer — each with three axes. This sensor is useful for detecting angular rotation and tap detections. On the upside, it is an incredibly accurate IMU; on the downside, it is the most expensive component in the tiny robot brain. Microbots offers CodeCell with and without the IMU.

Bugeja states the primary goal for CodeCell was to make it as compact as possible. This goal led to a few trade-offs. For example, there are components on both sides of the PCB. So, while the through-hole and castellated GPIO pins provide flexibility for custom PCB attachment, doing so may require a cut-out in the PCB for surface mount soldering. Another trade-off is the absence of a "Boot" button, a common feature in ESP32 projects. However, the two pins needed to activate the bootloader are conveniently located next to each other, making them easy to short with a small wire.

While CodeCell's PCB measures 18 by 18 millimeters, these measurements exclude the ESP32's antenna. The SoC extends one dimension by an additional 5 millimeters. Another trade-off is the placement of the USB-C connector. It is directly underneath the ESP32. This decision means there could be interference with the ESP32's antenna when a USB cable connects to the CodeCell. However, Bugeja feels the interference is minimal and is really only an issue during development.

You can purchase CodeCell from the Microbots online store. The base unit costs €14,99, and the price for CodeCell with the nine-axis IMU is €29,99.