unable to read 32kHz oscillator signal on ETR pin

[santulaz]

Hi all,

i'm working with a STM32F469i-discovery board trying to read the  external signal at 32kHz coming from an RTC module. The oscillating signal voltage is a CMOS type. I'm using TIM2_ETR input located on pin PA15 configured as follow. I'm not able to read any pulse on the pin and every time that I run the system the oscillator voltage fall to 0.3V instead of the 2.5V that I can measure when the system is not running.

I test the oscillator signal on Arduino board and I can read the right frequency just connectin the oscillator output to Arduino pin8.  Thanks for the support.

[AScha.3]

Ok, what you see on pin with scope ? clk signal ok ?

+

set counter period to some lower value for test, maybe 2000 .

[waclawek.jan]

In particular CCER=1 means, that CH1 is enabled; and as in CCMR1 it is set to Output compare, given pin turns to output (TIM2_CH1 is shared with TIM2_ETR on PA15).

I don't use Cube/CubeMX so can't tell how can you avoid this using Cube/CubeMX. It may be a bug in Cube/CubeMX.

I generally recommend you to use register-based programming instead, but some here find that an extereme approach.

JW

PS. Maybe similar https://community.st.com/t5/stm32-mcus-boards-and-hardware/tim2-tim3-tim4-ert-mode-on-nucleo-h743zi2/td-p/676201