Samsung S5PC100 User Manual page 682

S5PC100 USER'S MANUAL (REV1.0)
4 FUNCTION DESCRIPTION
4.1 FAST-SPEED INFRARED (FIR) MODE (IRDA 1.1)
In this FIR mode, data communicates at the baud rate speed of 4 Mbps. In the data transmission mode, the 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, if
infrared 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 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 are Phy-Error, Frame-Length
Error and CRC error. The last one, CRC error is checked after the entire payload data is received. The micro-
controller monitors the error status of the received frame by reading the Line Status Register (LSR) at the end of
the frame receiving.
The below diagram shows the frame structure of the FIR data frame (The specific information of the each field is
available 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 is selected from 4 to 32.
* NOTE: 4 PPM Coding
Data Bit Pair(DBP)
Start Flag Link Layer Frame(Payload)
00
01
10
11
CRC32
4PPM Data Symbol(DD)
1000
0100
0010
0001
IRDA
Stop Flag
8.4-3