Mbps Fir Frame Format; Figure 17-3. 4Ppm Modulation Example; Figure 17-4. Irda (4.0 Mbps) Transmission Format - Cirrus Logic EP93 Series User Manual

Receive data sample counter frequency = 6x pulse width, each time-slot sampled on third clock.

17.5.1.2 4.0 Mbps FIR Frame Format

When the 4.0 Mbps transmission rate is used, the high-speed serial/parallel (FIR) interface
within the FIR is used along with the 4PPM bit encoding. The high-speed frame format shown
in Figure 17-4, is similar to the SDLC format with several minor modifications: the start/stop
flags and CRC are twice as long and instead of one start flag, a preamble and start flag of
differing length are used.
64
symbols
Preamble
DS785UM1

Figure 17-3. 4PPM Modulation Example

8 4 DDs 4 DDs
symbols (8 bits) (8 bits)
Control
Start Flag Address
(optional)
Start Flag
|0000|1100|0000|1100|0110|0000|0110|0000|
|0000|1100|0000|1100|0000|0110|0000|0110|
Preamble
|1000|0000|1010|1000|... repeated 16 times

Figure 17-4. IrDA (4.0 Mbps) Transmission Format

Copyright 2007 Cirrus Logic
8180 DDs max 16 DDs
(2045 bytes) (32 bits)
Data CRC-32
IrDA
EP93xx User's Guide
8 symbols
Stop Flag
Stop Flag
17-15
17