STM32H7x3I-EVAL2 board: free pins on the I/O extender (MFX)?

[Pavel A.]

I need to hook few external signals to STM32H7x3I-EVAL rev. E, if possible without soldering or losing access to FMC, QSPI memories.

This board is much busier than Nucleo, I can find only few free pins on the default pinout.

The user manual (UM2198 rev.4, table 50) shows that MFX has three unused pins: 10,11,12.

How to connect to these pins? I cannot find a connector on the schema in UM2198.

On the schema, Fig. 59 all these MFX pins are connected to something. Are they really free to use?

[Paul1]

A. Consider getting a Nucleo, low cost and many many free pins. Paired with a breadboard you can use breadboard jumper wires to plug from the female headers on Nucleo to the breadboard.

NUCLEO-H743ZI - STM32 Nucleo-144 development board with STM32H743ZI MCU, supports Arduino, ST Zio and morpho connectivity - STMicroelectronic

(*You can get the Nucleo with many different STM32xxxx processors, by Package size: 100pin, 144pin, etc)

(Suggest finding a supply of STM32's, and designing your board to accept several different part numbers, given Covid shortages and all.

B.

Evaluate schematic and see if there are accessories you can disable to free pins. i.e. SPI: In code set the SS- pin to high, then the other pins can be used for other functions (SCK/MOSI/MISO)

Paul

[Pavel A.]

Thank you @Community member​ . I have several Nucleos already, and have to deal with EVAL.

Does your answer mean that there's no obvious way to connect to the MFX?

[Paul1]

Do (B), print out the schematics and go over them with highlighters marking what you can disable or disconnect.

Maybe with minor mods you can bring out useful signals on an existing connector.

Sorry but with the style of ST schematics I just don't have the time to dig as deeply as you are asking, my own work keeps me buried.

If you pick out pieces then we may be able to help, but that's all got time for.

You could also try contacting ST Support directly.

Paul

[Pavel A.]

Well it looks like all pins going to the LCD connector become available when the LCD is removed. Nothing to solder/unsolder.

This would free up a lot of pins, if the app won't require the LCD...