Executing Instructions for the Scribbler 2 Robots

The circuitry and firmware for the Scribbler 2 Robots can interpret about 30 basic commands, such as

• start motors, with designated speeds for the left and right wheels
• stop both robot motors
• beep a given pitch for a given duration
• retrieve data from specified sensors
• retrieve an image from the robot's camera
• etc.

Although details of the instructions vary, most utilize a 9-byte format:

• Byte 0: a code designating the operation to be executed
• Bytes 1-??: data needed for the command
• Bytes ??-8: unused

• generate a tone at a given pitch for a given duration:
  • byte 0: 113
  • bytes 1-2: pitch duration in milliseconds
  • bytes 3-4: pitch frequency in cycles/second
  • bytes 5-8: unused
• turn the robot at specified speeds for the left and right wheels
  • byte 0: 109
  • byte 1: left wheel power (0-99: backward; 100 stop; 101-200 forward)
  • byte 2: left wheel power (0-99: backward; 100 stop; 101-200 forward)
  • byte 3: -1
  • bytes 4-8: unused

A full list of Scribbler 2 robot instructions, including instruction formats, may be found at https://walker.cs.grinnell.edu/bluetooth-with-c/scribbler-commands.shtml

created 25 January 2021 last revised 26 January 2021

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