Figure 4a—Data packets are sparse and flexible. The ID byte immediately indicates what will follow is data. The payload is self-contained. The packet schedule allows you to assemble the full packet from any number of sensors without having to reinvent the packet structure. The total packet size is 1 + m reports × (1 ID byte + 2 bytes), where m is the number of sensors reporting, and n is the number of bytes of data or bytes of payload. b—We kept the command packet as simple as possible to keep the overhead low for sending a command to the car unit. This packet also accommodates messages to the LCD with a variable-sized field to contain the text string. The total packet size is equal to n bytes of data divided by the settings.