Let’s first make sure the sender micro:bit and receiver micro:bit in the cyber:bot work as expected with normal packets.  Since we are going to leave the cyber:bot tethered with USB, we’ll use some short distance maneuvers with low speeds and short run times.   

• Plug the battery pack’s plug into the cyber:bot board’s battery jack.
• Set the cyber:bot board’s PWR switch to 2.
• Click the Show serial buttons in both python.microbit.org editors.
• If the left speed prompt does not appear in the sender Serial terminal connected to the sender micro:bit, try clicking Hide serial, and then Show serial again.
• Type these responses to the prompts, and remember to press Enter after typing each value:
  • Enter left speed: 25
  • Enter right speed: 25
  • Enter ms to run: 500
• Verify that the cyber:bot moved forward slowly for a half a second.
• Decide on another maneuver, type in the prompts, and verify that the cyber:bot maneuvers as expected.

Now it is time to see the effect that a malformed packet can have.  

• Type these responses to the prompts, and remember to press Enter after typing each value:
  • Enter left speed: 25
  • Enter right speed: 25
  • Enter ms to run: -1
• Did the cyber:bot robot’s micro:bit display an error?  
• Did an exception appear in the terminal connected to the cyber:bot robot’s receiver micro:bit?

If your micro:bit was not tethered, it would be stuck until a human came and restarted it by pressing and releasing the micro:bit module’s reset button! That is not always possible in a competition, but you can do it now.

• On the cyber:bot, locate the micro:bit module’s reset button; it’s on the bottom side between the USB and battery sockets.
• Press and release it to restart the receiver micro:bit script execution.
• Type a maneuver into the Serial terminal connected to the sender micro:bit, and verify that you can control the cyber:bot robot’s motion again.