Samsung S3C2451X User Manual page 316

PWM TIMER
AUTO RELOAD & DOUBLE BUFFERING
S3C2451X PWM Timers have a double buffering function, enabling the reload value changed for the next timer
operation without stopping the current timer operation. So, although the new timer value is set, a current timer
operation is completed successfully.
The timer value can be written into Timer Count Buffer register (TCNTBn) and the current counter value of the
timer can be read from Timer Count Observation register (TCNTOn). If the TCNTBn is read, the read value does
not indicate the current state of the counter but the reload value for the next timer duration.
The auto-reload operation copies the TCNTBn into TCNTn when the TCNTn reaches 0. The value, written into the
TCNTBn, is loaded to the TCNTn only when the TCNTn reaches 0 and auto reload is enabled. If the TCNTn
becomes 0 and the auto reload bit is 0, the TCNTn does not operate any further.
Start Start
TCNTBn = 150 TCNTBn = 150
Auto-reload Auto-reload
Interrupt Interrupt
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
13-4
Specifications and information herein are subject to change without notice.
Write Write
TCNTBn = 100 TCNTBn = 100
150 150
Figure 13-3. Example of Double Buffering Function
Write Write
TCNTBn = 200 TCNTBn = 200
100 100 100 100
S3C2451X RISC MICROPROCESSOR
200 200