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for the h753 custom board- how to have additional gpios for extra sensors

Associate III

Since we have decided to create the prototype, the first requirement is ensuring that the chosen H753-EVL board is functioning properly. However, its GPIOs are already occupied with essential peripherals such as LTDC, FMC-SDRAM, SRAM, NOR flash, USB_FS, USB_HS, and Ethernet. Therefore, we need an additional 25 GPIOs for the thermal printer and its motor. Should we share the SRAM and NOR flash buses with SDRAM for any specific reason? Additionally, is it possible to use a 1024x600 display with the normal DWIN GUI and later switch to TouchGFX?

where,we dont' need stlink,audio,expansion and Arduino connector removing sram,norflash and using only qspi and sdram alone can give us gpios?? is that not affect any working of custom board after assembly.

Uwe Bonnes
Principal II

Consider I2C Portextenders or logic shift registers.

The LTDC and the frame buffer behave the same at a functional level irrespective of your windowing software choice.

These Kitchen-Sink board are not really suitable for prototyping additional functionality.

You can use SDRAM on a smaller subset of FMC pins than are needed for external SRAM/NOR/NAND. You can remove parts and recover pins that aren't used for any other purpose. Although an expensive board to hack up, and awkward high density connectors. Perhaps cheaper ArtPi, WeAct and FANKE boards that might be better proxies.

On your own solution you could use DSI, QSPI and SDRAM with fewer pins.

Expansion, perhaps make an IO Expander off the I2C. NXP has some parts, and ST has used slave STM32 parts for ancillary functions. You could hang a CPLD / FPGA off the FMC too

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Are you suggesting that an I2C port extender can be used to add up to 20 extra GPIOs on the H753-EVL board? I see that it has an MFX, which stands for Multi-Function Extension ports. Is this what you were referring to?


Pavel A.
Evangelist III

These extenders often have less than 20 pins. Take two of them. Or three. or four.

>it has an MFX, which stands for Multi-Function Extension ports.

This is ST own kludge, not a commercial part. But yes it is similar.


I was not referring especialy for the extension connector for the evalboard, as you asked about a custom board. Fot the eval boards, probably "External I2C connector " needs less wiring.


>we dont' need stlink,audio,expansion and Arduino connector too

No, st-link -> swd connector for debug you need .

If most other things on this board not needed, you want other hardware connect, then it would be better idea ,

to take a nucleo board and connect the things you want, for a first proto-test:


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The pin count and complexity of the Display & SDRAM tend to have me discount the NUCLEO's as proxy

WaveShare ? They have board and panels

Not specific recommendations, but starting points to their offerings

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  • Based on expert advice, for our first revision board, we've been editing the Altium files of the H753-EVL board. We replaced all BGA packages with QFN, especially the 208 MCU where footprint creation doesn't matter, and ensured that all I/O ports match. We also included the necessary decoupling capacitors according to VDD. Are these changes sufficient for the hardware to work properly? Mainly, we changed the BGA to LQFP in the memory section for SRAM, NOR flash, and the equivalent of the 256MB SDRAM because the EVL's SDRAM doesn't have a QFN option. That's all for now. I need to gain confidence that this approach will yield good results after laying out the board to work like the EVL or Disco board.

Additional Note: I used the same memory structure as the EVL (in QFN package) and utilized the DWIN display for initial purposes, which can also be used for commercial purposes. Later, if we need LVDS, we'll need to include RGB lines. This is why I'm concerned about the lack of pins. Should we use the extension port, or would an additional MCU be a better solution?

Right, or a cheaper "nucleo like" board (as i have also) , just need buy an st-link (if you dont have):


or with camera...




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