Motorola MPC823e - Page 742

Communication Processor Module
16-288 MPC823e REFERENCE MANUAL MOTOROLA
COMMUNICATION
16
PROCESSOR MODULE
SCCs
16.9.20.1 LOW-SPEED IRDA PROTOCOL. The low-speed IrDA protocol consists of a
data link layer and a physical layer.
• The data link layer is based on a preexisting ASYNC HDLC protocol standard. See
Section 16.9.19 The SCCx in Asynchronous HDLC Mode for more details. 0xC0 is
used as a start flag and 0xC1 is used as an end flag. Each character is compromised
out of a start bit, 8 data bits, no parity bit and ending with a stop bit, as shown in
Figure 16-94.
• The physical layer defines the electrical parameters of the signals between the
encoder/decoder module and the infrared transducer module. The signal waveform is
shown in Figure 16-94. For all signaling rates up to and including 115.2Kb/s, the
minimum pulse duration is the same—
3
/
16
of the bit duration for the 115.2Kb/s signal
(minus a protocol-defined tolerance). The maximum pulse duration is
3
/
16
of the bit
duration (plus a protocol-defined tolerance).
Figure 16-94. Low-Speed IrDA Data Format
0 101 00 11 0 1
START
BIT
DATA BITS
STOP
BIT
UART FRAME
INFRA
-
RED FRAME
3/16 BIT TIME
(A)
(B)