h8s-2138 Renesas Electronics Corporation., h8s-2138 Datasheet - Page 733

• Manufacturer Part Number: h8s-2138
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2100 Series
• Manufacturer: Renesas Electronics Corporation.

Section 23 Clock Pulse Generator
23.9
Clock Selection Circuit
This circuit selects the system clock used in the MCU.
The clock signal generated in the EXTAL/XTAL pin oscillator is selected as the system clock
when MCU is returned from high-speed mode, medium-speed mode, sleep mode, reset state, or
standby mode.
In sub-active mode, sub-sleep mode, and watch mode, the sub-clock signal input from EXCL pin
is selected as the system clock. In these modes, modules such as CPU, TMR0, TMR1, WDT0,
WDT1, and I/O ports operate on the SUB clock. The count clock for each timer is a clock
obtained by dividing the SUB clock.
Rev. 4.00 Jun 06, 2006 page 679 of 1004
REJ09B0301-0400