mc68hc08az60 Freescale Semiconductor, Inc, mc68hc08az60 Datasheet - Page 326

• Manufacturer Part Number: mc68hc08az60
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

MSCAN Controller (MSCAN08)
MC68HC08AZ60 — Rev 1.0
326
NOTE:
If the system clock is generated from a PLL, it is recommended to select
the crystal clock source rather than the system clock source due to jitter
considerations, especially at faster CAN bus rates.
A programmable prescaler is used to generate out of the MSCAN08
clock the time quanta (Tq) clock. A time quantum is the atomic unit of
time handled by the MSCAN08.
A bit time is subdivided into three segments
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
page 340 and
1. For further explanation of the underlying concepts please refer to ISO/DIS 11 519-1, Section
10.3.
Freescale Semiconductor, Inc.
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For More Information On This Product,
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.
MSCAN Controller (MSCAN08)
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MSCAN08 Bus Timing Register 1
Bit rate=
f
Tq
=
No. of time quanta
Presc value
MSCAN08 Bus Timing Register 0
f
MSCANCLK
f
Tq
1
(see
Figure
on page 341).
8).
MOTOROLA
22-mscan
on