The IPC-Lite drivers include basic functions to manipulate 16 or 32-bit words. These include read and write command functions, functions for setting and clearing bits, and for calling functions on the other processor. All write functions also have “protected” counterparts, allowing IPC commands to be used to write to write-protected registers. The Message Direction is indicated in the function name. For instance, function calls for the M3 to execute a command on the C28 would begin with “IPCLiteMtoC”, and function calls for the C28 to execute a command on the M3 would begin with “IPCLiteCtoM”. Two flags, which are passed in as parameters to these functions, facilitate communications. The IPC interrupt flag informs the requesting processors that a command is pending. The IPC status flag reports back to the sending processor if a command was invalid. Additionally, the M3 can use the IPC lite drivers to communicate with the C28x boot ROM before the C28 application code starts running. During C28x boot time, IPCMTOCINT1 and FLAG32 are reserved for C28x boot ROM communications. After boot time, the application can use these flags for normal IPC communications. The IPC-Lite drivers can also be used in parallel with the main IPC software drivers. 1 IPC channel can be dedicated for IPC-Lite usage while all other ISR’s can be utilized by the main IPC drivers.