Motor Driver and Power Distribution Board for Romi Chassis

Overview

This motor driver and power distribution board is designed specifically for the Romi chassis as a convenient way to drive the chassis’s motors and power the rest of the electronics that make up your robot. It features two DRV8838 motor drivers, one for each of the chassis’s motors, and a powerful switching step-down regulator that can supply a continuous 2.5 A at 5 V or 3.3 V. The board has slots for soldering in the Romi chassis battery contact tabs, and it incorporates the power switching and distribution functionality from the Power Distribution Board for Romi Chassis, so it offers all of the same features: reverse voltage protection, several power switching options, and easy access to the various power busses.

Like the smaller Power Distribution Board, this board has a small pushbutton already installed and offers convenient points for connecting external pushbutton or tactile switches in parallel. It also offers several alternate pushbutton connection options that result in push-on-only or push-off-only operation, and additional inputs enable further power control options like allowing your robot to turn off its own power. Alternatively, the board can be reconfigured to disable the pushbutton circuit and give control to the small installed slide switch.

The board’s power buses are accessible through a set of 0.1″-spaced pins that are compatible with standard 0.1″ male and 0.1″ female headers, and also through a larger set of holes that are compatible with 3.5mm-pitch terminal blocks (you can combine a 2-pin block and a 3-pin block into a single 5-pin block that spans the three power holes and two ground holes).

Two 1/4″ #2-56 screws and two #2-56 nuts are included for mounting the board to the Romi chassis, and two low-profile female headers are included for connecting the motors to the board. If you have Romi encoders installed on your motors with the header pins down, they will plug directly into the board via these female headers.

More documentation is coming soon, but for now, see the simplified schematic diagram (276k pdf).

Dimensions

General specifications

Identifying markings

Notes:

1

Board only; no screws or nuts.

2

Of VSW.

3

This is also the peak output current of the motor driver; over-current protection can trigger as low as 1.9 A.