I want to interface a Nucleo-H743ZI2 board (MB1364E) with a memory chip using STM32's FMC.

In order to do this I need to free up the following 4 pins, to be used by the morpho connector:

PE1, currently yellow user LED, needed for FMC_NBL1.
PD8, currently ST_LINK_RX , needed for FMC_D13.
PD9, currently ST_LINK_TX, needed for FMC_D14.
PD10, currently USB_OTG_FS_PWR_EN, needed for FMC_D15.

(Current use verified through STM32CubeIDE)

I am following the schematics below (MB1364):


And the user manual for MB1364 found here:



So, pin PE1, according to the schematics can be disconnected by removing R71. I have verified that PE1 connects to R71 using a multimeter, and the schematics/manual show no solder bridge to disconnect the LED, so the first one I consider solved by removing the resistor R71.


I do not know the purpose of USB_OTG_FS_PWR_EN, however I believe it is related to CN13 USB, which I do not need. Page 28 of the manual shows PD10 connected to SB77, with SB77 on by default, and flipping it to off should enable morpho connector use. I have verified there is continuity with SB77 and SB77 is on by default, so the solution here would be to remove SB77.

PD8 and PD9:

PD8 and PD9 are used for USART3 communication which I do not need. Pins PD8 and PD9 default's configuration, according to page 27 of the manual, is SB5 and SB6 ON, and SB7 and SB4 off. To use PD8 and PD9 with the morpho connector, I should flip these solder bridges (from ON to OFF and vice-versa). However, my board from factory comes with SB4, SB5 and SB7 off, and only SB6 on. Furthermore, I've checked with a multimeter and I can't find continuity between PD8/PD9 and any of these solder bridges.

On the same page (page 27 of the manual), in the text description, it says "Flying wires have to be connected between PD8/PD9 (USART3 available on SB19/SB12)". I've checked and found that PD8/PD9 have continuity with SB19/SB12.

Finally, the schematics document shows PD8/PD9 connected to SB82/SB81, which I have confirmed also with the multimeter.

I am at a loss for what solder bridges to set on/off in order to free up PD8/PD9.


1 Answer 1


As per the answer given to me on ST's forum, this is a mistake in the board's manual:


SB19 and SB12 should be turned off, in order to free PD8 and PD9 for FMC use.


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