Tethered Terminal Control Script

This is a simple tethered application where you type in left and right wheel speeds, and run time in milliseconds, into a terminal.  When you press Enter, your text gets parsed and executed by the micro:bit, which then makes the cyber:bot execute the maneuver.

Example Script: terminal_controlled_bot_tethered_intro

  • Make sure the cyber:bot’s batteries are connected, and its 3-position switch is set to 2.
  • Add the cyber:bot module to your project.
  • Enter this script and save it as terminal_controlled_bot_tethered_intro.  
  • Flash the script into the micro:bit.

Example Script: terminal_controlled_bot_tethered_intro

# terminal_controlled_bot_tethered_intro

from cyberbot import *

sleep(1000)

print("\nSpeeds are -100 to 100\n")

while(True):
    text = input("Enter left speed: ")
    vL = int(text)

    text = input("Enter right speed: ")
    vR = int(text)

    text = input("Enter ms to run: ")
    ms = int(text)

    bot(18).servo_speed(vL)
    bot(19).servo_speed(-vR)
    sleep(ms)
    bot(18).servo_speed(None)
    bot(19).servo_speed(None)

    print()

Since your cyber:bot is currently tethered, it’s best to use low speeds and short run times.  Otherwise, your cyber:bot might try to roll beyond the tether length.  In other words, it’ll try to unplug itself from the USB cable, or maybe roll off the table.

  • Use the Open Serial button to start the terminal.  
  • Click in the terminal and type 25 in response to the Enter right speed: prompt, then press Enter.
  • Type 25 in response to the Enter left speed: prompt, then press Enter.
  • Type 750 in response to the Enter ms to run: prompt, and press Enter.
  • Verify that your cyber:bot rolled forward for about ¾ of a second.
  • Next, try -25, -25, and 750.  Did it roll backwards?
  • Now, try 25, -25, 750.  Did it pivot to the right?
  • Try 25, 10, 750 for a curving motion.
  • Can you make it turn in place left and right?
  • Try causing an exception by typing non-digits in response to one of the prompts. 

For example, what happens if you type abc and press enter?  For now, you can press/release the reset button to restart the app.  You will add some exception handling in the your turn section to prevent this from happening.