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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Timer/Counter Mode
To select this mode, bits PTnM1 and PTnM0 in the PTMnC1 register should be set to 11
respectively. The Timer/Counter Mode operates in an identical way to the Compare Match Output
Mode generating the same interrupt flags. The exception is that in the Timer/Counter Mode the
PTMn
output pin is not used. Therefore the above description and Timing Diagrams for the Compare
Match Output Mode can be used to understand its function. As the TM output pin is not used in this
mode, the pin can be used as a normal I/O pin or other pin-shared function.
PWM Output Mode
To select this mode, bits PTnM1 and PTnM0 in the PTMnC1 register should be set to 10
respectively. The PWM function within the PTMn is useful for applications which require functions
such as motor control, heating control, illumination control etc. By providing a signal of fixed
frequency but of varying duty cycle on the PTMn output pin, a square wave AC waveform can be
generated with varying equivalent DC RMS values.
As both the period and duty cycle of the PWM waveform can be controlled, the choice of generated
waveform is extremely flexible. In the PWM Output Mode, the PTnCCLR bit has no effect on the
PWM operation. Both of the CCRA and CCRP registers are used to generate the PWM waveform,
one register is used to clear the internal counter and thus control the PWM waveform frequency,
while the other one is used to control the duty cycle. The PWM waveform frequency and duty cycle
can therefore be controlled by the values in the CCRA and CCRP registers.
An interrupt flag, one for each of the CCRA and CCRP, will be generated when a compare match
occurs from either Comparator A or Comparator P. The PTnOC bit in the PTMnC1 register is used
to select the required polarity of the PWM waveform while the two PTnIO1 and PTnIO0 bits are
used to enable the PWM output or to force the PTMn output pin to a fixed high or low level. The
PTnPOL bit is used to reverse the polarity of the PWM output waveform.
• 16-bit PTMn, PWM Output Mode, Edge-aligned Mode
CCRP
1~65535
0
Period
1~65535
10�4
D�ty
CCRA
• 10-bit PTMn, PWM Output Mode, Edge-aligned Mode
CCRP
1~1023
0
Period
1~10�3
10�4
D�ty
CCRA
If f
SYS
=4MHz, PTMn clock source select f
SYS
/4, CCRP=512 and CCRA=128,
The PTMn PWM output frequency=(f
SYS
/4)/512=f
SYS
/2048=1.9531kHz, duty=128/512=25%.
If the Duty value defined by the CCRA register is equal to or greater than the Period value, then the
PWM output duty is 100%.