SLAA202B February 2005 – December 2018 MSP430F149 , MSP430F149 , MSP430F2252-Q1 , MSP430F2252-Q1 , MSP430F2272-Q1 , MSP430F2272-Q1 , MSP430F2274 , MSP430F2274 , MSP430FG4619 , MSP430FG4619
The physical (IrPHY) layer is responsible for the sending and receiving of frames, some framing as beginning- and end-of-frame flags, and cyclic redundancy checks (CRC) or check sums. The latter are used as means of error detection mechanisms. Even though there is no means by which to repair the data (if the data is known to be corrupted), it could be requested again.
A frame at the IrPHY level is identified by 10 extra beginning-of-frame (XBOF) flags, 1 byte each as specified by the IrDA Lite documentation. After the XBOF flags are sent, a single beginning- of-frame (BOF) flag, 1 byte, is sent followed by data (payload). At the end of each frame, there are 2 bytes which compose the frame check sum (FCS) followed by a single end-of-frame (EOF) flag marking the end of the frame. Figure 16 shows the frame structure.