Technical notes and images
Controller and power features
- Controller: ESP32-S3-WROOM-1U-N16R8, with sensor inputs and six actuator channels.
- Battery system: 5S lithium-ion, with a 21 V full-charge setting and a separate adapter input.
- Power conversion: six TPSM63610 buck-converter power modules, providing 12 V, 6.8 V, 5 V and 3.3 V rails. The power stages use high-current inductors.
- Charge control: BQ24650 charging at approximately 3 A nominal, with precharge, constant-current/constant-voltage control, automatic termination and recharge.
- Cell protection and balancing: BQ7791508 protection against cell overvoltage, undervoltage and overcurrent, with autonomous passive balancing enabled.
- Servo channels: three DS3225MG channels, with up to 4 A available per channel.
- DC motor interfaces: three 12 V brushed-DC driver channels using DRV8874PWPR ICs.
- Communication: THVD1450 RS-485 interface with Modbus.
Hands-on checks
During a test with three servos held at stall, no noticeable heating was observed on the controller board. One charging check showed similar individual-cell readings of approximately 3.7 V.
Servo specifications
The DS3225 specifications list 21 kgf·cm stall torque at 5 V and 24.5 kgf·cm at 6.8 V, with stall currents of 1.9 A and 2.3 A respectively.
PCB layouts and bottom-side view
