Uif Bit Remapping; Clock Source - STMicroelectronics RM0365 Reference Manual

Basic timers (TIM6)
Figure 277. Counter timing diagram, update event when ARPE=1 (TIMx_ARR
23.3.3

UIF bit remapping

The IUFREMAP bit in the TIMx_CR1 register forces a continuous copy of the Update
Interrupt Flag UIF into the timer counter register's bit 31 (TIMxCNT[31]). This allows to
atomically read both the counter value and a potential roll-over condition signaled by the
UIFCPY flag. In particular cases, it can ease the calculations by avoiding race conditions
caused for instance by a processing shared between a background task (counter reading)
and an interrupt (Update Interrupt).
There is no latency between the assertions of the UIF and UIFCPY flags.
23.3.4

Clock source

The counter clock is provided by the Internal clock (CK_INT) source.
The CEN (in the TIMx_CR1 register) and UG bits (in the TIMx_EGR register) are actual
control bits and can be changed only by software (except for UG that remains cleared
automatically). As soon as the CEN bit is written to 1, the prescaler is clocked by the internal
clock CK_INT.
Figure 278
without prescaler.
699/1080
shows the behavior of the control circuit and the upcounter in normal mode,
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preloaded)
RM0365