Rev. 1.60
116
August 20, 2019
Rev. 1.60
117
August 20, 2019
BS66F340/BS66F350/BS66F360/BS66F370
Touch A/D Flash MCU with LED Driver
BS66F340/BS66F350/BS66F360/BS66F370
Touch A/D Flash MCU with LED Driver
Timer/Counter Mode
To select this mode, bits CTnM1 and CTnM0 in the CTMnC1 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
CTMn 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 CTMn 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 CTnM1 and CTnM0 in the CTMnC1 register should be set to 10
respectively. The PWM function within the CTMn 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 CTMn 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 mode, the CTnCCLR 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. Which register is used to control either frequency
or duty cycle is determined using the CTnDPX bit in the CTMnC1 register. 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 CTnOC bit in the CTMnC1 register is used
to select the required polarity of the PWM waveform while the two CTnIO1 and CTnIO0 bits are
used to enable the PWM output or to force the TM output pin to a fixed high or low level. The
CTnPOL bit is used to reverse the polarity of the PWM output waveform.
• 10-bit CTMn, PWM Mode, Edge-aligned Mode, CTnDPX=0
CCRP
001b
010b
011b
100b
101b
110b
111b
000b
Period
128
256
384
512
640
768
896
1024
Duty
CCRA
If f
SYS
=16MHz, CTMn clock source is f
SYS
/4, CCRP=2 and CCRA=128,
The CTMn PWM output frequency=(f
SYS
/4)/256=f
SYS
/1024=15.625kHz,
duty=128/256=50%.
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%.
• 10-bit CTMn, PWM Mode, Edge-aligned Mode, CTnDPX=1
CCRP
001b
010b
011b
100b
101b
110b
111b
000b
Period
CCRA
Duty
128
256
384
512
640
768
896
1024
The PWM output period is determined by the CCRA register value together with the CTMn clock
while the PWM duty cycle is defined by the CCRP register value.