
MSCAN08 Controller (MSCAN08)
Technical Data
MC68HC08AZ32A — Rev 1.0
344
MSCAN08 Controller (MSCAN08)
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MOTOROLA
A bit time is subdivided into three segments
(1)
(see
Figure 20-8
).
SYNC_SEG: This segment has a fixed length of one time
quantum. Signal edges are expected to happen within this section.
Time segment 1: This segment includes the PROP_SEG and the
PHASE_SEG1 of the CAN standard. It can be programmed by
setting the parameter TSEG1 to consist of 4 to 16 time quanta.
Time segment 2: This segment represents PHASE_SEG2 of the
CAN standard. It can be programmed by setting the TSEG2
parameter to be 2 to 8 time quanta long.
The synchronization jump width (SJW) can be programmed in a range
of 1 to 4 time quanta by setting the SJW parameter.
The above parameters can be set by programming the bus timing
registers, CBTR0–CBTR1, see
MSCAN08 Bus Timing Register 0
on
page 358 and
MSCAN08 Bus Timing Register 1
on page 359).
NOTE:
It is the user’s responsibility to make sure that the bit timing settings are
in compliance with the CAN standard,
Table 20-8
gives an overview on the CAN conforming segment settings
and the related parameter values.
1. For further explanation of the underlying concepts please refer to ISO/DIS 11 519-1, Section
10.3.
f
Tq
=
f
MSCANCLK
Presc value
Bit rate=
No. of time quanta
f
Tq
F
Freescale Semiconductor, Inc.
n
.