Samsung 8-Bit CMOS Microcontroller, S3C9228/P9228 user manual Oscillator Control Register Osccon

S3C9228/P9228 CLOCK CIRCUITS

OSCILLATOR CONTROL REGISTER (OSCCON)

The oscillator control register, OSCCON, is located in address D3H. It is read/write addressable and has the following functions:

—System clock selection

—Main oscillator control

—Sub oscillator control

OSCCON.0 register settings select Main clock or Sub clock as system clock.

After a reset, Main clock is selected for system clock because the reset value of OSCCON.0 is "0".

The main oscillator can be stopped or run by setting OSCCON.3.

The sub oscillator can be stopped or run by setting OSCCON.2.

Oscillator Control Register (OSCCON)

D3H, R/W

MSB

.7

.6

.5

.4

.3

.2

.1

.0

LSB

Not used for S3C9228

System clock selection bit: 0 = Main oscillator select 1 = Sub oscillator select

Not used for S3C9228

Sub oscillator control bit: 0 = Sub oscillator RUN

1 = Sub oscillator STOP

Main oscillator control bit: 0 = Main oscillator RUN

1 = Main oscillator STOP

Figure 7-8. Oscillator Control Register (OSCCON)

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