Chapter 5 Clock Generator; Clock Generator Functions; Clock Generator Configuration - NEC mPD780344 Series User Manual

8-bit single-chip microcontrollers
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5.1 Clock Generator Functions

The clock generator generates the clock to be supplied to the CPU and peripheral hardware. The following two types
of system clock oscillators are available.
(1) Main system clock oscillator
This circuit oscillates at frequencies of 2 to 10 MHz. Oscillation can be stopped by executing the STOP instruction
or setting the processor clock control register (PCC).
(2) Subsystem clock oscillator
The circuit oscillates at a frequency of 32.768 kHz. Oscillation cannot be stopped. If the subsystem clock oscillator
is not used, the internal feedback resistor can be disabled by the processor clock control register (PCC). This enables
to reduce the power consumption in the STOP mode.
The ×4 subclock circuit can also be selected by the subclock select register (SSCK).

5.2 Clock Generator Configuration

The clock generator consists of the following hardware.

CHAPTER 5 CLOCK GENERATOR

Table 5-1. Clock Generator Configuration
Item
Control registers
Processor clock control register (PCC)
Subclock select register (SSCK)
Oscillators
Main system clock oscillator
Subsystem clock oscillator
User's Manual U15798EJ2V0UD
Configuration
113

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