MC68HC08AZ32A Datasheet, PDF (352/456 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
MSCAN08 Controller (MSCAN08)
20.13.5 Transmit Buffer Priority Registers
Address: $05bD
Bit 7
6
5
4
3
2
1
Bit 0
Read:
PRIO7
Write:
PRIO6
PRIO5
PRIO4
PRIO3
PRIO2
PRIO1
PRIO0
Reset: u
u
u
u
u
u
u
u
Figure 20-13. Transmit Buffer Priority Register (TBPR)
PRIO7–PRIO0 — Local Priority
This field defines the local priority of the associated message buffer.
The local priority is used for the internal prioritisation process of the
MSCAN08 and is defined to be highest for the smallest binary
number. The MSCAN08 implements the following internal
prioritisation mechanism:
• All transmission buffers with a cleared TXE flag participate in the
prioritisation right before the SOF is sent.
• The transmission buffer with the lowest local priority field wins the
prioritisation.
• In case more than one buffer has the same lowest priority, the
message buffer with the lower index number wins.
20.14 Programmer’s Model of Control Registers
The programmer’s model has been laid out for maximum simplicity and
efficiency. Figure 20-14 gives an overview on the control register block
of the MSCAN08.
Technical Data
352
MC68HC08AZ32A — Rev 1.0
MSCAN08 Controller (MSCAN08)
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