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Theta
This library provides a Microsoft Makecode package for 4tronix / Robotixlab Theta robot
The simplest way to drive the robot is by using the robotGo(...) or robotGoms(...) 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:
theta.robotGo(RXDirection.Forward, 60)Move backward at speed 100 for 2000 ms:
theta.robotGoms(RXDirection.Reverse, 100, 2000)You can also spin/rotate the robot with the rotate(...) or rotatems(...) blocks
Rotate left at speed 70:
theta.robotRotate(RXRobotDirection.Left, 70)Rotate right at speed 50 for 400ms:
theta.robotRotatems(RXRobotDirection.Right, 50, 400)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.
Slowly coast to a stop:
theta.robotStop(RXStopMode.Coast)Stop rapidly with braking:
theta.robotStop(RXStopMode.Brake)If you want more fine grain control of individal motors, use the motorMove(...) block to drive each motor separately, 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 theta.motorGo(RXDirection.Forward, 60):
theta.motorMove(RXMotor.Both, RXDirection.Forward, 60)Drive left motor in reverse at speed 30:
theta.motorMove(RXMotor.Left, RXDirection.Reverse, 30)Drive forward in a leftward curve:
theta.motorMove(RXMotor.Left, RXDirection.Forward, 40)
theta.motorMove(RXMotor.Right, RXDirection.Forward, 70)The small DC motors used in the theta 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).
If robot leaves straight line to the right by about 10cm over 2m, bias it to the left by 5%:
theta.motorBias(RXRobotDirection.Left, 5)If robot leaves straight line to left by 25cm, bias it to the right by 15%:
theta.motorBias(RXRobotDirection.Right, 15)If you have mounted the optional sonar sensor for the theta you can
also use the readSonar(..) function to read the distance to obstacles.
let distance_us = theta.readSonar(RXPingUnit.MicroSeconds)
let distance_cm = theta.readSonar(RXPingUnit.Centimeters)
let distance_in = theta.readSonar(RXPingUnit.Inches)The Theta has 14 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 or built-in colour selection - look at Javascript to see the difference):
theta.ledsColor(0x00FF00)
theta.ledsColor(RXColors.Green)Clear all Fireleds:
theta.ledClear()Set the FireLed at position 0 to 13 to selected colour. eg. set Fireled 3 to Red:
theta.setPixel(3, 0xff0000)Set all the FireLeds to Rainbow (uses the colour wheel from Red to Purple). Choose true or false to start at the beginning or the end:
theta.ledRainbow(true)Shift FireLeds up/down one place, blanking the first/last FireLed:
theta.ledShift(false)Rotate FireLeds by shifting up/down one and replace the first/last with the last/first:
theta.ledRotate(true)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:
theta.setUpdateMode(RXMode.Manual)
theta.setUpdateMode(RXMode.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 = theta.convertRGB(50, 100, 200)Set brightness of FireLeds to 100
theta.ledBrightness(100);MIT
Theta=github:4tronix/Theta#v1.0.5