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9-5
PULSE-WIDTH MODULATOR
Figure 9-3. PWM Output Waveforms
9.4 PROGRAMMING THE FREQUENCY AND PERIOD
The PWM module provides two selectable, fixed PWM output frequencies for a specified
internal operating frequency (f). Table 9-3 shows the PWM output frequencies for common
operating frequencies on the 8XC196NP. The value of CON_REG0.0 determines the output fre-
quency by enabling or disabling the clock prescaler. Use the following formulas to calculate the
output frequency (F
PWM
) or output period (T
PWM
).
Clock Prescaler
Disabled
÷2 Clock Prescaler
Enabled
÷4 Clock Prescaler
†
Enabled
F
PWM
(in MHz) =
T
PWM
(in µs) =
†
80C196NU only.
Duty
Cycle
0
0
0
0
0
PWM Control
Register Value
0% 00H
10% 19H
50% 80H
90% E6H
99.6% FFH
Output Waveform
A0119-02
f
512
----------
f
1024
---- ---- --- --
f
2048
-------------
512
f
----------
1024
f
---- ---- --- --
2048
f
-------------