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3-4200-D1-2.0-0403
STIr4200
USB/IrDA Bridge Controller
OFFICIAL
PRODUCT
DOCUMENTA TI ON
5. IR FRAMING FORMATS
5.1.
Transmit Frame Format
5.1.1.
SIR Transmit Frame
The SIR rates include 2.4, 9.6, 19.2, 38.4, 57.6, and 115.2 Kbps. For SIR, the frame
presented to the USB bulk transmit interface must be organized in the following
fashion as shown in Figure 4.
0x55
0xAA
LSB size
MSB size
0xC0
0xC0
0xC0
0xC0
0xC0
…
BOF = Beginning of frame characters
The number of beginning of frame
characters is determined during the
negotiation stage.
Header ID
Data
Data
Data
Data
Data
Data
A
CI
Address/Control/Information Fields
Special characters must be escaped
Original Data
Escaped Data
0xC0
0x7D 0xE0
0xC1
0x7D 0xE1
0x7D
0x7D 0x5D
…
LSB CRC
MSB CRC
FCS : 16 bit CRC-CCITT
0xC1
EOF - End of frame
Number of following bytes
Data
Figure 4. SIR Transmit Frame Format