MC68HC812A4 Datasheet, PDF (155/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Clock Module
Block Diagram
10.3.1 Clock Generators
The clock module generates four types of internal clock signals derived
from the oscillator:
1. T-clocks — Drives the CPU
2. E-clock — Drives the bus interfaces, BDM, SPI, and ATD
3. P-clock — Drives the bus interfaces, BDM, SPI, and ATD
4. M-clock — Drives on-chip modules such as the timer, SCI, RTI,
COP, and restart-from-stop delay time
Figure 10-2 shows clock timing relationships. Four bits in the CLKCTL
register control the base clock and M-clock divide selection (÷1, ÷2, ÷4,
and ÷8 are selectable).
T1CLK
T2CLK
T3CLK
T4CLK
INTERNAL ECLK
PCLK
MCLK
1
MCLK
2
MCLK
4
MCLK
8
Note: The MCLK depends on the chosen divider settings in the CLKCTL register.
Figure 10-2. Internal Clock Relationships
Advance Information
MOTOROLA
Clock Module
MC68HC812A4 — Rev. 3.0
155