Documentation

Power Board

A photo of a power board The Power Board distributes power to the SR kit from the battery. It provides six individual general-purpose power outputs along with a separate power connector for the Brain Board.

It also holds the internal On|Off switch for the whole robot as well as the Start button which is used to start your robot code running.

Board Diagram

A diagram of a power board

Connectors

There are six power output connectors on the board, labelled L0–L3, H0, and H1. These are enabled when your robot code is started, and supply around 11.1V (±15%). They should be used to connect to the motor and servo board power inputs. The “H” connectors will supply more current than the “L” connectors.

The 5V connectors can be used to connect low-current devices that take 5V inputs, such as the Brain Board.

There is also a Micro USB B connector which should be used to connect the Brain Board for control of the power board.

Finally, there are connectors for external Start and On|Off switches. You may connect any push-to-make latching switch for the On|Off button, or a push-to-make button for the start button.

If you intend to use only the internal On|Off switch, you must connect a CamCon to the On|Off connector with a wire connecting one pin to the other pin on the same connector.

Indicators

LED Meaning Initial power-up state
PWR|FLAT Green when powered
Flashing red and green when the battery is low
Green
5V Green when 5V is being supplied Green
H0-1, L0-3 Green when the output is on 1
Red when the output’s current limit is reached
Off
RUN|ERROR Orange on power-up, or USB reset
Flashing green when ready to run
Solid green when running or booting
Orange

On power-up, the Power Board will emit some beeps, which are related to the version of the firmware it has installed.

If the Power Board starts beeping (and all the outputs turn off) then this means that the whole board’s current limit has been triggered.

Controls

Control Use
ON|OFF Turns the power board on, when used in conjunction with an external switch
START Starts your program (can be used instead of the robot WiFi interface)

Case Dimensions

The case measures 83x99x24mm. Don’t forget that the cables will stick out.

Specification

Parameter Value
Main battery fuse current 40A
Overall current limit2 30A
High current outputs (H0-1) 20A
Low current outputs (L0-3) 10A
Motor rail output voltage (nominal) 11.1V ± 15%
Maximum output current per 5V channel 1A

Designs

You can access the schematics and source code of the firmware for the power board in the following places. You do not need this information to use the board but it may be of interest to some people.

  1. The outputs only turn on when your program runs (specifically, when the Robot object is created). 

  2. If overall current limit is exceeded, the Power Board will turn off and start beeping.