HD404654 Datasheet, PDF (48/111 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404654 Series
Prescalers
The MCU has the following prescaler S.
The prescaler operating conditions are listed in table 21, and the prescaler output supply is shown in figure
32. The timer A–D input clocks except external events and the serial transmit clock except the external
clock are selected from the prescaler outputs, depending on corresponding mode registers.
Prescaler Operation
Prescaler S: 11-bit counter that inputs a system clock signal. After being reset to $000 by MCU reset,
prescaler S divides the system clock. Prescaler S keeps counting, except at MCU reset.
Table 21 Prescaler Operating Conditions
Prescaler
Prescaler S
Input Clock
System clock
Reset Condition
MCU reset
Stop Conditions
MCU reset, stop mode
System
clock
Prescaler S
Figure 32 Prescaler Output Supply
Timer A
Timer C
Timer D
Serial 1
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