SR API Quick Reference

This page contains a quick guide to the sr.robot3 API.

For more information, make sure you check the rest of the documentation.

Import the API

In order to use the sr.robot3 API you first need to import it into your code:

from sr.robot3 import *

Initialising your robot

Standard Initialisation

R = Robot()

Initialisation without waiting for the start button

R = Robot(auto_start=True)

# Code here runs before the start button is pressed


Initialisation with extra logging

You can also tell the robot to print extra logging information, although this is quite noisy.

R = Robot(verbose=True)

Selecting which board to control

If you only have one board of a given type plugged into your robot, then you can use its singular name:


If you have multiple boards of a given type plugged into your robot, you must index them by serial number:


Power Board

The outputs on the power board will turn on when you initialise your robot.

Turn on and off the power outputs

# Turn all of the outputs on

# Turn all of the outputs off

# Turn a single output on
R.power_board.outputs[OUT_H0].is_enabled = True

# Turn a single output off
R.power_board.outputs[OUT_H0].is_enabled = False

Reading voltage and current

# Read the current of an individual output
current = R.power_board.outputs[OUT_H0].current

# Read the current and voltage from the LiPo battery
voltage = R.power_board.battery_sensor.voltage
current = R.power_board.battery_sensor.current


The power board has an on-board piezoelectric buzzer.

# Play a standard note C6 -> C8 included for 0.5s, Note.C6)

# Play a tone at 1047Hz for 1 second, 1047)


Powering Motors

You can set the power of each motor on the board between -1 and 1.

If you change the power of your motor too rapidly, the overcurrent protection may be triggered.

R.motor_board.motors[0].power = 1
R.motor_board.motors[1].power = -1

Setting a motor to COAST is equivalent to power level 0.

# This is the same operation
R.motor_board.motors[0].power = COAST
R.motor_board.motors[0].power = 0

Braking Motors

You can also brake a motor, which will quickly slow the motor.

R.motor_board.motors[0].power = BRAKE
R.motor_board.motors[1].power = -1


You can set the position of each servo output on the board between -1 and 1.

R.servo_board.servos[0].position = -1
R.servo_board.servos[1].position = 1

You can also set the position to 0, which is the approximate centre.


Taking a photo

It can sometimes be useful to save a photo of what markers the robot can see:"my-photo.png")  # Save my-photo.png to the USB drive

Looking for markers

You can take a photo with the camera and search for markers:

markers =

There are various bits of information available about visible markers:

for marker in markers:  # The ID of the marker
    marker.size  # Physical size of the marker in mm.

    marker.distance  # Distance away from the camera in mm

    # Cartesian coords of the marker

    # Spherical coords of the marker

    # Orientation of the marker


Setting the mode of a pin

R.ruggeduino.pins[4].mode = OUTPUT
R.ruggeduino.pins[4].mode = INPUT
R.ruggeduino.pins[4].mode = INPUT_PULLUP

Digital Write

You can set the output for a pin of the Ruggeduino:

R.ruggeduino.pins[4].mode = OUTPUT


Digital Read

You can read a digital value from the pins of the Ruggeduino:

R.ruggeduino.pins[3].mode = INPUT

value = R.ruggeduino.pins[3].digital_read()

Analogue Read

You can read an analogue value from the analogue pins of the Ruggeduino:

value = R.ruggeduino.pins[A0].analogue_read()


The API also makes some information about where your code is running

Starting Zone for a match

zone =  # -> 0, 1, 2, or 3

Arena Information

arena = R.arena # -> 'A'

Robot Mode

This is set to COMP when your robot is in a match.

robot_mode = R.mode # -> DEV or COMP

USB Key Path

This is the path to where your USB key is mounted.

You can use this to save files and information to the drive.

usb_key_path = R.usbkey # -> pathlib.Path