MC68HC908GZ8 Datasheet, PDF (183/344 Pages) Motorola, Inc – Microcontrollers

MSCAN08 Controller (MSCAN08)
Programmer’s Model of Control Registers
16.12.5 Transmit Buffer Priority Registers
Address:
Read:
Write:
Reset:
$05bD
Bit 7
6
5
4
3
2
1
PRIO7 PRIO6 PRIO5 PRIO4 PRIO3 PRIO2 PRIO1
Unaffected by reset
Figure 16-13. Transmit Buffer Priority Register (TBPR)
Bit 0
PRIO0
PRIO7–PRIO0 — Local Priority
This field defines the local priority of the associated message buffer. The local
priority is used for the internal prioritization process of the MSCAN08 and is
defined to be highest for the smallest binary number. The MSCAN08
implements the following internal prioritization mechanism:
• All transmission buffers with a cleared TXE flag participate in the
prioritization right before the SOF is sent.
• The transmission buffer with the lowest local priority field wins the
prioritization.
• In case more than one buffer has the same lowest priority, the message
buffer with the lower index number wins.
16.13 Programmer’s Model of Control Registers
The programmer’s model has been laid out for maximum simplicity and efficiency.
Figure 16-14 gives an overview on the control register block of the MSCAN08.
Addr.
$0500
$0501
$0502
$0503
Register
Bit 7
6
CMCR0
Read:
Write:
0
0
5
4
3
2
1
Bit 0
0
SYNCH
TLNKEN
SLPAK
SLPRQ SFTRES
CMCR1 ^Read:
0
0
0
0
0
LOOPB WUPM CLKSRC
Write:
Read:
CBTR0 _Write:
SJW1
SJW0
BRP5
BRP4
BRP3
BRP2
BRP1
BRP0
CBTR1
Read:
Write:
SAMP
TSEG22 TSEG21 TSEG20 TSEG13 TSEG12 TSEG11 TSEG10
= Unimplemented
R
= Reserved
Figure 16-14. MSCAN08 Control Register Structure (Sheet 1 of 3)
MC68HC908GZ8
Freescale Semiconductor
MSCAN08 Controller (MSCAN08)
Data Sheet
183