MC68HC08AZ32A Datasheet, PDF (117/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

MSCAN08
RxBG
RxFG
RXF
Message Storage
CPU08 IBUS
Tx0
TXE
PRIO
Tx1
TXE
PRIO
Tx2
TXE
PRIO
Figure 11-3. User Model for Message Buffer Organization
An overrun condition occurs when both the foreground and the background receive message buffers are
filled with correctly received messages with accepted identifiers and another message is correctly
received from the bus with an accepted identifier. The latter message will be discarded and an error
interrupt with overrun indication will be generated if enabled. The MSCAN08 is still able to transmit
messages with both receive message buffers filled, but all incoming messages are discarded.
11.4.3 Transmit Structures
The MSCAN08 has a triple transmit buffer scheme to allow multiple messages to be set up in
advance and to achieve an optimized real-time performance. The three buffers are arranged as shown in
Figure 11-3.
MC68HC08AZ32A Data Sheet, Rev. 2
Freescale Semiconductor
117