ST STM32F301 6 Series Reference Manual page 371

RM0366
Note: An asynchronous (clockless) operation is only guaranteed when the programmable filter is
disabled. If it is enabled, a fail safe clock mode (for example by using the internal PLL and/or
the CSS) must be used to guarantee that break events are handled.
When one of the breaks occurs (selected level on one of the break inputs):
•
The MOE bit is cleared asynchronously, putting the outputs in inactive state, idle state
or even releasing the control to the GPIO controller (selected by the OSSI bit). This
feature is enabled even if the MCU oscillator is off.
•
Each output channel is driven with the level programmed in the OISx bit in the
TIMx_CR2 register as soon as MOE=0. If OSSI=0, the timer releases the output control
(taken over by the GPIO controller), otherwise the enable output remains high.
• When complementary outputs are used:
–
–
–
•
The break status flag (BIF and B2IF bits in the TIMx_SR register) is set. An interrupt is
generated if the BIE bit in the TIMx_DIER register is set.
• If the AOE bit in the TIMx_BDTR register is set, the MOE bit is automatically set again
at the next update event (UEV). As an example, this can be used to perform a
regulation. Otherwise, MOE remains low until the application sets it to '1' again. In this
case, it can be used for security and the break input can be connected to an alarm from
power drivers, thermal sensors or any security components.
Note: If the MOE is reset by the CPU while the AOE bit is set, the outputs are in idle state and
forced to inactive level or Hi-Z depending on OSSI value.
If both the MOE and AOE bits are reset by the CPU, the outputs are in disabled state and
driven with the level programmed in the OISx bit in the TIMx_CR2 register.
Note: The break inputs are active on level. Thus, the MOE cannot be set while the break input is
active (neither automatically nor by software). In the meantime, the status flag BIF and B2IF
cannot be cleared.
In addition to the break input and the output management, a write protection has been
implemented inside the break circuit to safeguard the application. It allows the configuration
of several parameters to be freezed (dead-time duration, OCx/OCxN polarities and state
when disabled, OCxM configurations, break enable and polarity). The application can
choose from 3 levels of protection selected by the LOCK bits in the TIMx_BDTR register.
Refer to
can be written only once after an MCU reset.
Figure 134
The outputs are first put in inactive state (depending on the polarity). This is done
asynchronously so that it works even if no clock is provided to the timer.
If the timer clock is still present, then the dead-time generator is reactivated in
order to drive the outputs with the level programmed in the OISx and OISxN bits
after a dead-time. Even in this case, OCx and OCxN cannot be driven to their
active level together. Note that because of the resynchronization on MOE, the
dead-time duration is slightly longer than usual (around 2 ck_tim clock cycles).
If OSSI=0, the timer releases the output control (taken over by the GPIO controller
which forces a Hi-Z state), otherwise the enable outputs remain or become high as
soon as one of the CCxE or CCxNE bits is high.
Section 17.4.20: TIM1 break and dead-time register
shows an example of behavior of the outputs in response to a break.
RM0366 Rev 5
Advanced-control timer (TIM1)
(TIM1_BDTR). The LOCK bits
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