[022] ROBOT MAINBOARD

A robot mainboard is where power, motion, intelligence, and system reliability all meet. You can’t treat each block in isolation — they’re all connected, and the design has to reflect that.

LiFePO4 was chosen for its thermal stability, long cycle life, and safety profile. Battery management has to hold up during motor startup and current peaks without destabilizing the rest of the system.

The ESP32-S3-WROOM-1-N16R8 handles control, Wi-Fi, and system supervision. H-bridge drivers run the DC motors in both directions. Beyond the schematic, what makes the board solid is the partitioning between power electronics, control logic, and sensitive digital domains: motor current paths, decoupling, grounding strategy, thermal dissipation. On a board like this, everything is connected to everything else.

[014] PORTABLE BATTERY-POWERED DEVICE WITH DC MOTOR

A portable device with a rechargeable Li-Ion battery, a DC motor, physical buttons for local control, and Bluetooth for wireless interaction. All coordinated by an EFM8BB10F8G, a compact microcontroller that handles both energy management and motion control.

The motor brings its usual set of challenges: startup current, electrical noise, switching behavior. The battery has to sustain current peaks while remaining stable for the rest of the electronics. Bluetooth adds flexibility — the user can operate the device wirelessly without being limited to the physical interface.

The main challenge here is making all of it coexist in a compact enclosure without each block disturbing the others. A solid system integration exercise in a small package.

[013] EMBEDDED 4G TRACKING DEVICE

GPS, 9-axis IMU, 4G modem with 2G fallback, BLE, Li-Ion battery — all on one compact platform built around an STM32L152.

4G is the primary communication path, with 2G taking over if coverage degrades. BLE provides a local interaction layer through a smartphone — configuration and status access without going through the cellular network. The IMU adds motion awareness on top of positioning: not just where the device is, but how it’s moving.

In a product like this, energy management is its own engineering challenge. The cellular modem, GNSS receiver, and IMU all have very different power profiles, and the whole thing has to run on battery in unpredictable field conditions. A real system architecture problem from start to finish.