Skim through the iRobot Roomba Open Interface Specification document $($posted with the lab$).$ Notice the information about commands that can be sent to the iRobot and the sensor packets it returns to the TM$4$C microcontroller. A commands quick reference table is shown on page $33.$ A sensors quick reference starts on page $37.$

a$)$ Name one of the OI commands used in this lab and give its opcode.

b$)$ Name one of the sensors used in this lab and give the number of data bytes used for the sensor value.