Datasheet

510
32133D–11/2011
UC3D
25.6.7 Synchronization
Both the timebase counter and the spread spectrum counter can be reset and the duty cycle
registers can be written through the user interface of the module. This requires a synchroniza-
tion between the PB and GCLK clock domains, which takes a few clock cycles of each clock
domain. The BUSY bit in SR indicates when the synchronization is ongoing. Writing to the mod-
ule while the BUSY bit is set will result in discarding the new value.
Note that the duty cycle registers will not be updated with the new values until the timebase
counter reaches its top value, in order to avoid glitches. The BUSY bit in SR will always be set
during this updating and synchronization period.
25.6.8 Interrupts
When the timebase counter overflows, the Timebase Overflow bit in the Status Register
(SR.TOFL) is set. If the corresponding bit in the Interrupt Mask Register (IMR) is set, an interrupt
request will be generated.
Since the user needs to wait until the user interface is available between each write due to syn-
chronization, a READY bit is provided in SR, which can be used to generate an interrupt
request.
The interrupt request will be generated if the corresponding bit in IMR is set. Bits in IMR are set
by writing a one to the corresponding bit in the Interrupt Enable Register (IER), and cleared by
writing a one to the corresponding bit in the Interrupt Disable Register (IDR). The interrupt
request remains active until the corresponding bit in SR is cleared by writing a one to the corre-
sponding bit in the Status Clear Register (SCR).