DocID024409 Rev 2

17/23

AN4277

Using the break function with other MCU resources

22

Comparators output can be optionally enabled as alternate function on the related GPIO

pin, in push-pull or open-drain mode, for signaling to other devices or for debugging

purposes.

Table 5. Comparator output connected externally to break inputs,

with low break polarity

Description

Register

Bit

Configuration

TIM1/8/20 BRK polarity

TIMx_BDTR

BKP

0 (active low), it means that the external signal

goes low during the fault

Comparator output polarity

COMPx_CSR COMPxPOL

0 (not inverted), comparators input connected

as shown in previous sections

TIM1/8/20 BKIN AF

GPIOxAFRL

or

GPIOxAFRH

-

AF enabled on BKIN pin selected among

available

TIM1/8/20 BRK enable

TIMX_BDTR

BKE

1

COMPx out selection

COMPx_CSR COMPxOUTSEL

0001: TIM1 BRK

0011: TIM8 BRK

1100: TIM20 BRK

Table 6. Comparator output connected externally to break inputs,

with high break polarity

Description

Register

Bit

Configuration

TIM1/8/20 BRK/BRK2 polarity TIMx_BDTR

BKP or BK2P

1 (active high), it means that the external signal

goes high during the fault

Comparator output polarity

COMPx_CSR COMPxPOL

0 (not inverted), comparators input connected

as shown in previous sections

TIM1/8/20 BKIN/BKIN2 AF

GPIOxAFRL

or

GPIOxAFRH

-

AF enabled on BKIN/BKIN2 pin selected among

available

TIM1/8/20 BRK/BRK2 enable

TIMX_BDTR

BKE or BK2E

1

COMPx out selection

COMPx_CSR COMPxOUTSEL

0001: TIM1 BRK

0010: TIM1 BRK2

0011: TIM8 BRK

0100: TIM8 BRK2

0101: TIM1 BRK2 + TIM8 BRK2

1100: TIM20 BRK

1101: TIM20 BRK2

1110: TIM1 BRK2 + TIM8 BRK2 + TIM20 BRK2