HD404328US View Datasheet(PDF) - Hitachi -> Renesas Electronics

Part Name

Description

Manufacturer

HD404328US

4-Bit Microcontroller

Hitachi -> Renesas Electronics 

HD404328 Series

Internal Oscillator Circuit

A block diagram of the internal oscillator circuit is shown in figure 22. As shown in table 21, crystal and

ceramic oscillators can be connected to OSC1 and OSC2, and a 32.768-kHz oscillator can be connected to

X1 and X2. The system oscillator can also be operated by an external clock. Bit 3 of the miscellaneous

register (MIS: $00C) must be set according to the frequency of the oscillator connected to OSC1 and OSC2.

Note: If the MIS register setting does not match the oscillator frequency, subsystems using 32-kHz

oscillation will malfunction. Set the system oscillator frequency to anything outside the range of

1.0 MHz to 1.6 MHz when using 32-kHz oscillation.

Miscellaneous register (MIS): $00C

3

2

1

0

Initial value: 0000,

R/W: W

tRC selection

R12/SO PMOS off

Setting for switching

the system oscillator’s

frequency

MIS

Bit 3

0

1

Figure 21 Miscellaneous Register

System Oscillator’s

Frequency

1.6 MHz to 4.5 MHz

0.4 MHz to 1.0 MHz

OSC2

OSC1

X1

X2

System

oscillator

Divide-by-8

circuit

Sub-system

oscillator

Divide-by-8

circuit

Timing

generator

circuit

Synch.

(tcyc)

Timing

generator

circuit

Synch.

(tsubcyc )

Mode

control

circuit

Figure 22 Internal Oscillator Circuit

System

clock

(øCPU)

System

clock

(øPER)

Time-base

clock

(ø CLK)

37

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