oyvindmo / bitbot

Microsoft MakeCode package for 4tronix Bit:Bot robot

MakeCode Package for 4tronix BitBot Robot

This library provides a Microsoft Makecode package for 4tronix BitBot and BitBot XL, see https://4tronix.co.uk/bitbot/

Selecting the Model of BitBot

You can now use either a classic BitBot or a BitBot XL. The pins used for motors and sensors are different so it is necessary to select the correct model. You can force the selection using:

bitbot.select_model(BBModel.Auto)  // this will force the BitBot to re-select the correct model
bitbot.select_model(BBModel.Classic)
bitbot.select_model(BBModel.XL)

Or you can leave the BitBot to automatically decide and not use this command at all. It will do this at the start of the program so it requires the BitBot to be switched on to make the correct selection. If you do it automatically then you can use the same hex code for both models. You can check what model is being used by:

bitbot.getModel()

Driving the robot

The simplest way to drive the robot is by using the go(...) or goms(...) blocks. With each of these blocks you specify Forward or Reverse, and a speed from 0 to 100. Both motors will be driven at the selected speed and direction.

// Move forward at speed 60 forever
bitbot.go(BBDirection.Forward, 60)

// Move backward at speed 100 for 2000 ms
bitbot.goms(BBDirection.Reverse, 100, 2000)

You can also spin/rotate the robot with the rotate(...) or rotatems(...) blocks

// Rotate left at speed 70
bitbot.rotate(BBRobotDirection.Left, 70)

// Rotate right at speed 50 for 400ms
bitbot.rotatems(BBRobotDirection.Right, 50, 400)

Stopping

When the motor speed is set to zero then it stops. However, we can also use the motor itself to create a reverse generated current to brake much quicker. This helps when aiming for more accurate manoeuvres. Use the stop(...) command to stop with braking, or coast to a halt.

bitbot.stop(BBStopMode.Coast) # slowly coast to a stop
bitbot.stop(BBStopMode.Brake) # rapidly brake

Driving the motors individually

If you want more fine grain control of individal motors, use bitbot.move(...) to drive each motor either forward or reverse. You can specify the direction (Forward or Reverse) and speed between 0 and 100. If the left motor turns slower than the right motor, the robot will turn to the left

// Drive both motors forward at speed 60. Equivalent to bitbot.go(BBDirection.Forward, 60)
bitbot.move(BBMotor.Both, BBDirection.Forward, 60)

// Drive left motor in reverse at speed 30
bitbot.move(BBMotor.Left, BBDirection.Reverse, 30)

// Drive forward in a leftward curve
bitbot.move(BBMotor.Left, BBDirection.Forward, 40)
bitbot.move(BBMotor.Right, BBDirection.Forward, 70)

Making the Robot Drive Straight

The small DC motors used in the BitBot and many other small robots are not guaranteed to go at the same speed as each other. This can cause the robot to veer off the straight line, either to left or to right, even when both motors are programmed to go at the same speed. We can partially correct for this by adding a direction bias to the motor speed settings. If your robot is veering to the right, then set the bias to the left. Conversely, if your robot is turning to the left, then set the bias to the right. It varies with speed and battery condition etc, but an approximation is that a 10% bias will result in about 15cm (6 inches) change of course over about 2m (6 feet). Note that the bias setting does not affect the old style motor blocks.

// eg. robot leaves straight line to the right by about 10cm over 2m, so bias it to the left by 5%
bitbot.BBBias(BBRobotDirection.Left, 5)

// eg. robot leaves straight line to left by 25cm, so bias it to the right by 15%
bitbot.BBBias(BBRobotDirection.Right, 15)

Buzz sound

To use the buzzer, just use bitbot.buzz(..) function with either 1 (sound) or 0 (no-sound).

// Buzz for 100 ms
bitbot.buzz(1);
basic.pause(100);
bitbot.buzz(0);

Read line sensor

The BitBot has two line-sensors: left and right. To read the value of the sensors, use bitbot.readLine(..) function.

// Read left and right line sensor
let left = bitbot.readLine(BBLineSensor.Left);
let right = bitbot.readLine(BBLineSensor.Right);

Read light sensor

Light sensors can be read using bitbot.readLight(..) function.

// Read left and right light sensor
let left = bitbot.readLight(BBLightSensor.Left);
let right = bitbot.readLight(BBLightSensor.Right);

Read sonar value

If you have mounted the optional sonar sensor for the BitBot you can also use the bitbot.sonar(..) function to read the distance to obstacles.

// Read sonar values
let v1 = bitbot.sonar(BBPingUnit.MicroSeconds);
let v2 = bitbot.sonar(BBPingUnit.Centimeters);
let v3 = bitbot.sonar(BBPingUnit.Inches);

FireLed Functions

The BitBot has 12 FireLeds fitted. By default, the FireLeds are automatically updated after every setting. This makes it easy to understand. However, it can slow down some effects so there is a block provided to switch the update mode to Manual or Automatic:

// Set all FireLeds to Green (hard-coded RGB color)
bitbot.setLedColor(0x00FF00)
// Set all FireLeds to Green (built-in colour selection)
bitbot.setLedColor(BBColors.Green)

// Clear all leds
bitbot.ledClear()

// Set the FireLed at position 0 to 11 to selected colour.
// eg. set Fireled 3 to Red
bitbot.setPixelColor(3, 0xff0000)

// Set all the FireLeds to Rainbow (uses the colour wheel from Red to Purple)
bitbot.ledRainbow()

// Shift FireLeds up one place, blanking the first FireLed
bitbot.ledShift()

// Rotate FireLeds by shifting up one and replace the first with the last
bitbot.ledRotate()

There are some more advanced blocks that allow you to select colours using separate RGB values and select the brightness of the FireLeds. The brightness is set to 40 by default, but can go as high as 255 You should be careful not to look directly at them when they are bright as they can damage eyes.

// Switch FireLeds Update Mode to Manual or Automatic
bitbot.setUpdateMode(BBMode.Manual);
bitbot.setUpdateMode(BBMode.Auto);

// Select colour from separate Red, Green and Blue values
// Each of the Red, Green and Blue values can range from 0 to 255.
// This example produces a pale blue colour
let myColour = bitbot.convertRGB(50, 100, 200);

// Set brightness of FireLeds to 100
bitbot.ledBrightness(100);

Supported targets

• for PXT/microbit

License

MIT