Samsung S3C9454B, User Manual

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S3C9454B/F9454B 8-BIT PWM
11-1
11
8-BIT PWM (PULSE WIDTH MODULATION
)
OVERVIEW
This microcontroller has the 8-bit PWM circuit. The operation of all PWM circuit is controlled by a single control
register, PWMCON.
The PWM counter is a 8-bit incrementing counter. It is used by the 8-bit PWM circuits. To start the counter and
enable the PWM circuits, you set PWMCON.2 to "1". If the counter is stopped, it retains its current count value;
when re-started, it resumes counting from the retained count value. When there is a need to clear the counter you
set PWMCON.3 to "1".
You can select a clock for the PWM counter by set PWMCON.6–.7. Clocks which you can select are f
OSC
/64,
f
OSC
/8, f
OSC
/2, f
OSC
/1.
FUNCTION DESCRIPTION
PWM
The 8-bit PWM circuits have the following components:
— 6-bit comparator and extension cycle circuit
— 6-bit reference data register (PWMDATA.7–.2)
— 2-bit extension data register (PWMDATA.1–.0)
— PWM output pins (P0.6/PWM)
PWM Counter
To determine the PWM module's base operating frequency, the upper 6-bits of counter is compared to the PWM
data (PWMDATA.7–.2). In order to achieve higher resolutions, the lower 2-bits of the counter can be used to
modulate the "stretch" cycle. To control the "stretching" of the PWM output duty cycle at specific intervals, the
lower 2-bits of counter value is compared with the PWMDATA.1–.0.