Freescale Semiconductor MPC5200B - Manual (Page 724)

Functional Description
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 20-45
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Figure 20-18. Receiving An IFR With the BDLC module
20.8.7.2 Receiving IFR Exceptions
This basic IFR receiving flow can be interrupted for the same reasons as a normal message reception. The IFR receiving process can be
adversely affected due to a CRC error, an Invalid or Out of Range Symbol or due to a receiver overrun caused by the CPU failing to service
an RxIFR interrupt in a timely fashion. For a description of how these exceptions can affect the IFR receiving process, refer to
Section
20.8.5.4, Receiving Exceptions .
20.8.8 Special BDLC Module Operations
There are a few special operations which the BDLC module can perform. What follows is a brief description of each of these functions and
when they might be used.
20.8.8.1 Transmitting Or Receiving A Block Mode Message
The BDLC module, because it handles each message on a byte-by-byte basis, has the inherent capability of handling messages any number
of bytes in length. While during normal operation this requires the user to carefully monitor message lengths to ensure compliance with SAE
J1850 message limits, often in a production or diagnostic environment messages which exceed the SAE J1850 limits can be beneficial. This
is especially true when large amounts of configuration data need to be downloaded over the SAE J1850 network.
Enter IFR Receive
Routine
Is DLCBSVR = $1C/$18?
No
Store received IFR byte
(in case of LOA)
Is this IFR
Yes
No
Is DLCBSVR = $04?
No
Yes
(EOF)
of any interest?
Is this an IFR
Yes
No
xmit reflection?
Yes
A
B
Once BDLC module Detects
EOF, IFR
Discard received
IFR bytes
reception is complete
Yes
No
Is DLCBSVR = $08?
Exit IFR Receive
Routine
B
(Error Detected)
(RxIFR)
Read byte in DLCBDR
Filter received IFR byte
Set IMSG bit in DLCBCR1
Store received IFR byte
B
A