SMBP2501BPB datasheet(89/107 Pages) SONIX

89 / 107 page

SN8P2501B

8-Bit Micro-Controller

SONiX TECHNOLOGY CO., LTD

Page 89

Version 2.1

8.4.3 PWM Duty with TC0R Changing

In PWM mode, the system will compare TC0C and TC0R all the time. When TC0C<TC0R, the PWM will output logic

“High”, when TC0C≧ TC0R, the PWM will output logic “Low”. If TC0C is changed in certain period, the PWM duty will

change in next PWM period. If TC0R is fixed all the time, the PWM waveform is also the same.

TC0C overflow

and TC0IRQ set

TC0C = TC0R

0xFF

TC0C Value

0x00

PWM0 Output

Period

Above diagram is shown the waveform with fixed TC0R. In every TC0

C overflow PWM output “High, when TC0C≧

TC0

R PWM output ”Low”. If TC0R is changing in the program processing, the PWM waveform will became as following

diagram.

1st PWM

Update PWM Duty

2nd PWM

Update PWM Duty

0xFF

TC0C Value

0x00

PWM0 Output

Period

3th PWM

TC0C overflow

and TC0IRQ set

Old TC0R

New TC0R

Update New TC0R!

Old TC0R < TC0C < New TC0R

Update New TC0R!

New TC0R < TC0C < Old TC0R

TC0C > = TC0R

PWM High > Low

TC0C < TC0R

PWM Low > High

In period 2 and period 4, new Duty (TC0R) is set. TC0 is double buffer design. The PWM still keeps the same duty in

period 2 and period 4, and the new duty is changed in next period. By the way, system can avoid the PWM not

changing or H/L changing twice in the same cycle and will prevent the unexpected or error operation.

SMBP2501BPB Datasheet(PDF) 89 Page - SONiX Technology Company

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