Why are PC8 and PC9 not connected on the Morpho connector of my NUCLEO-H743ZI2?

[JArwe.1]

As per UM2407, page 42, PC8 and PC9 should be Pins 1 and 2 of the CN12 Morpho connector. On the silk screen on the board the corresponding pins are labeled accordingly as well.

However on my NUCLEO-H743ZI2 board I can not get a signal from the MCU on these pins. PC8 and PC9 on the Zio connector work as they are supposed to.

With the multimeter I measure a high impedance between these Pins on the Morpho connector and their equivalents on the Zio connector, so they do not seem to be connected on the PCB.

I checked if there are any missing solder bridges, but UM2407 does not mention any related to these pins.

Am I missing something? Is my board faulty? Is this an error in the documentation?

[Peter BENSCH · Accepted solution]

If you look at the schematics of the NUCLEO-H743ZI2, you will notice that pins CN12.1 and CN12.2 are not connected, because SB14 and SB15 are marked DNF = Do Not Fit. Maybe it is some mistake in UM2407, as it mentions them in table 14 Default=ON (closed), but according to the schematics it should be read as Default=OFF.

Of course you can close them, they are located at the bottom layer, almost exactly in the middle between CN11.16 and CN12.16 (red shaped, green for orientation):

 

When your question is answered, please close this topic by choosing Select as Best.

/Peter

[JArwe.1]

Besides listing the wrong default value, UM2407 does not even mention in any way that these two solder bridges are related to PC8 and PC9. It just refers to them as SDMMC_D0 and SDMMC_D1, which makes it quite difficult to figure out what is wrong when you are specifically searching for PC8 and PC9.

In any case, your answer cleared things up, thank you!