I'd like to output the PPS waveform on the STM32MP157D-EV1 board. But it's not outputting.

[kKim.1]

I found the pin of PG8 on the GPIO pin map on the board.

So I connected to PG8 and GND to connect with oscilloscope.

In the picture, the blue line is the oscilloscope's GND port.

I connected the board and the oscilloscope like the picture above. And I entered the command to output the PPS signal, but the waveform is not displayed.

I looked up various answers and followed the answers such as PTP activation command and adding PG8 to AF11.

What am I doing wrong?

For your information, I used the following image when I uploaded the image.

en.FLASH-stm32mp1-openstlinux-5.15-yocto-kirkstone-mp1-v22.11.23\stm32mp1-openstlinux-5.15-yocto-kirkstone-mp1-v22.11.23\images\stm32mp1\flashlayout_st-image-weston\optee 

FlashLayout_emmc_stm32mp157d-ev1-optee.tsv

[kKim.1]

I checked the various documents on the board, and I could find the reason.

I tracked the PPS Out pin PG8 (pin 11) in the circuit diagram document on the board and found that it was disconnected. 

I found 'SB23' in the area where the CPU board is located, and after applying the resistor, I confirmed that the PPS signal is output normally.

 

I don't know why it was released with a cut off.