MOD5234-100IR NetBurner Inc, MOD5234-100IR Datasheet - Page 477

• Manufacturer Part Number: MOD5234-100IR
• Description: MOD5234 10/100 ETHERNET MODULE
• Manufacturer: NetBurner Inc
• Type: Controllers & Processorsr

Specifications of MOD5234-100IR

• Interface: I²C, SPI, UART
• Voltage - Supply: 2.5V
• Mounting Type: Surface Mount
• Package / Case: Module
• Product: Modules
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Format: -
• Baud Rates: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant
• Other names: Q4483564

21.4 Functional Overview
The FlexCAN module is flexible in that each one of its 16 message buffers (MBs) can be assigned
either as a transmit buffer or a receive buffer. Each MB, which is up to 8 bytes long, is also
assigned an interrupt flag bit that indicates successful completion of either transmission or
reception.
An arbitration algorithm decides the prioritization of MBs to be transmitted based on either the
message ID or the MB ordering. A matching algorithm makes it possible to store received frames
only into MBs that have the same ID programmed on its ID field. A masking scheme makes it
possible to match the ID programmed on the MB with a range of IDs on received CAN frames.
Data coherency mechanisms are implemented to guarantee data integrity during MB manipulation
by the CPU.
Before proceeding with the functional description, an important concept must be explained. A
message buffer is said to be “active” at a given time if it can participate in the matching and
arbitration algorithms that are happening at that time. An Rx MB with a 0000 code is inactive
(refer to
MB not programmed with either 0000 or 1000 will be temporarily deactivated (will not participate
in the current arbitration/matching run) when the CPU writes to the C/S field of that MB.
21.4.1 Transmit Process
The CPU prepares or changes an MB for transmission by executing the following steps:
Freescale Semiconductor
1. Writing the control/status word to hold Tx MB inactive (CODE = 1000).
2. Writing the ID word.
MBn[RTR
0
0
]
Table
21-13). Similarly, a Tx MB with a 1000 code is inactive (refer to
Table 21-14. Message Buffer Code for Tx Buffers (Continued)
Initial Tx
Code
1010
1110
Transmission
Successful
Code After
1010
1010
MCF5235 Reference Manual, Rev. 2
Transmit a data frame whenever a remote request frame with
the same ID is received. This message buffer participates
simultaneously in both the matching and arbitration processes.
The matching process compares the ID of the incoming remote
request frame with the ID of the MB. If a match occurs, this
message buffer is allowed to participate in the current arbitration
process and the CODE field is automatically updated to 1110 to
allow the MB to participate in future arbitration runs. When the
frame is eventually transmitted successfully, the code
automatically returns to 1010 to restart the process again.
This is an intermediate code that is automatically written to the
message buffer as a result of match to a remote request frame.
The data frame will be transmitted unconditionally once, and
then the code will automatically return to 1010. The CPU can
also write this code with the same effect.
Description
Table
Functional Overview
21-14). An
21-23