Samsung S5PC100, User Manual, Page: 586 / 1863

S5PC100 USER’S MANUAL (REV1.0) PULSE WIDTH MODULATION TIMER
7.1-9
3.5 INITIALIZE TIMER (SETTING MANUAL-UP DATA AND INVERTER)
Because an auto-reload operation of the timer occurs when the down counter reaches to 0, a starting value of the
TCNTn has to be defined by the user at first. In this case, the starting value must be loaded by manual update bit.
The sequence of starting a timer is as follows:
1. Write the initial value into TCNTBn and TCMPBn.
2. Set the manual update bit and clear only manual update bit of the corresponding timer.
Note: We recommend you to set the inverter on/off bit (whether inverter is used or not).
3. Set the start bit of corresponding timer to start the timer
3.6 PWM (PULSE WIDTH MODULATION)
Write TCMPBn=60
Write TCMPBn=50
Write TCMPBn=40
Write TCMPBn=30
Write TCMPBn=30
Write TCMPBn
= next PWM
60 50
40
30
30
Figure 7.1-6 Example of PWM
Use TCMPBn to implement PWM feature. PWM frequency is determined by TCNTBn. A PWM value is
determined by TCMPBn as shown in the Figure 7.1-6.
For higher PWM value, decrease TCMPBn value. For lower PWM value, increase TCMPBn value. If output
inverter is enabled, the increment/ decrement may be opposite.
Because of double buffering feature, TCMPBn, for a next PWM cycle, is written by ISR at any point of current
PWM cycle.