IRCC2.0 SMSC Corporation, IRCC2.0 Datasheet - Page 64

• Manufacturer Part Number: IRCC2.0
• Description: Infrared Communications Controller
• Manufacturer: SMSC Corporation

CRC Select Timing
During transmit if the CRC Select control is low
the FCS is assumed to be part of the message
payload data sent from the host and the
hardware CRC generator is not engaged (Figure
During transmit if the CRC Select control is high
the FCS is assumed not to be part of the
message data sent from the host, the hardware
CRC generator is engaged, and the FCS result is
appended to the host payload data (Figure 29).
During receive, if the CRC Select control is high,
the output from the hardware CRC generator is
FIFO Empty
CRC Select
Data Done
TC
FIFO Empty
CRC Select
Data Done
FIGURE 29 - IrDA FIR FRAME WITH HARDWARE CRC
FIGURE 28 - IrDA FIR FRAME WITH SOFTWARE CRC
TC
BOF
BOF
A
A
64
28). During receive if the CRC Select control is
low the hardware CRC generator is not engaged,
no comparison with the received FCS is made,
and the state of the configuration register CRC
Error flag is undefined (see CRC Select, bit 6, on
page 40).
compared to the CRC from the received
message and the result recorded in the
configuration register CRC Error flag. Note: for
all IrDA FIR received messages, the FCS is sent
to the host through the FIFO regardless of the
state of the CRC Select control.
C
C
I
I
CRC
(HW)
FCS
FCS
EOF
EOF