Samsung S3C6400X User Manual page 1112

S3C6400X RISC MICROPROCESSOR
FUNCTION DESCRIPTION
FAST-SPEED INFRARED (FIR) MODE (IRDA 1.1)
In FIR mode, data communicates at the baud rate speed of 4 Mbps. In the data transmission mode, core encodes
the payload data into 4PPM format and attaches the Preamble, Start Flag, CRC-32, and Stop flag on the encoded
payload and shifts them out serially. In data receive mode, the core works in reverse direction. First, when Ir pulse
is detected, the core recovers receiver clock from the incoming data and removes the Preamble and Start Flag.
Then it extracts the payload from the received 4PPM data until it meets the Stop Flag. The core detects three
different kinds of errors which may occur in the middle of transmission. These errors are the Phy-Error, the
Frame-Length Error and the CRC error. The CRC error is checked when the entire payload data is received. The
micro-controller can monitor the error status of the received frame by reading the Line Status Register (LSR) at
the end of the each received frame.
The below diagram shows the frame structure of the fir data frame (The specific information of the each field can
be found in IrDA specification.)
Preamble
Preamble : 1000, 0000, 1010, 1000
Start Flag : 0000, 1100, 0000, 1100, 0110, 0000, 0110,0000
Stop Flag : 0000,1100, 0000, 1100, 0000, 0110, 0000, 0110
By programming the internal registers, the number of preambles can be selected from 4 to 32.
* Note: 4 PPM Coding
Start flag Link layer frame(Payload)
Data Bit Pair(DBP)
00
01
10
11
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
CRC32
4PPM Data Symbol(DD)
1000
0100
0010
0001
IRDA
Stop flag
38-5