mc68hc08qa24 Freescale Semiconductor, Inc, mc68hc08qa24 Datasheet - Page 357

• Manufacturer Part Number: mc68hc08qa24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

22.12 Memory Map
MC68HC08QA24
Freescale Semiconductor
NOTE:
The clock source flag (CLKSRC) in the MSCAN08 module control
register (CMCR1) (see
defines whether the MSCAN08 is connected to the output of the crystal
oscillator or to the PLL output.
The MSCAN08 clock is used to generate the atomic unit of time handled
by the MSCAN08: the time quantum. A bit time is subdivided into three
segments defined here. For further explanation of the underlying
concepts, refer to ISO/DIS 11519-1, Section 10.3.
The synchronization jump width (SJW) can be programmed in a range
of 1 to 4 time quanta by setting the SJW parameter.
These parameters can be set by programming the bus timing registers,
CBTR0–CBTR1, see
22.14.4 MSCAN08 Bus Timing Register
The user is responsible for making sure that the bit time settings comply
with the CAN standard.
conforming segment settings and the related parameter values.
The MSCAN08 occupies 128 bytes in the CPU08 memory space. The
absolute mapping is implementation dependent with the base address
being a multiple of 128. The background receive buffer can be read in
test mode only.
Due to design requirements, the absolute addresses and bit locations
may change with later revisions of this specification.
•
•
•
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.
CAN Controller
22.14.3 MSCAN08 Bus Timing Register 0
22.14.1 MSCAN08 Module Control
Table 22-2
gives an overview on the CAN
1).
CAN Controller
Technical Data
Register)
and
355