Post #4250993

2026-07-30 19:29 UTC

MCU wise, I'm looking at STM32H7s and similar high end processors. For now, only STM32 since that's what I have the most experience wise. And only density/package combos that are stocked at distributors and provide the parallel memory controller (FMC) allowing a MMIO link to the FPGA are in scope. FPGA wise, looking at Xilinx 7 series and UltraScale+ and Efinix Trion/Topaz/Titanium to start.

Replies (1)

@azonenberg@ioc.exchange 2026-07-30 19:44

The most attractive MCU option is the STM32H757ZIY6. Digikey doesn't stock it, and has a 5000 piece MOQ for $57521, but if I can source it elsewhere it has exactly the specs I want: * ~5x5mm WLCSP156 package * 2 MB of flash * 1 MB of SRAM (including 64 kB ITCM/128 kB DTCM) * 99 total GPIOs leaving plenty free after the memory bus * 480 MHz M7 + 240 MHz M4 ST does not list *any* distributors though, seems special order only? You can't even get samples that I can see, or order small quantities direct. The same part is also available in a 7x7 ball UFBGA169 which is only 2mm larger and has 112 GPIOs but otherwise mostly the same specs and Digikey has in stock for $21.49 @ 1 or $15.36 @ 50. So tentatively, this seems a good choice one way or another. It has an internal LDO/SMPS for the digital core and can run IOs at either 1.8 or 3.3V, but there's only one IO bank so I'm stuck running everything at 3.3V assuming I need at least *some* 3.3V stuff, and then if I need 1.8 it will have to be via the FPGA. This is generally how I've built my board-level MCU+FPGA systems in the past, nothing unusual here other than using a higher density package. So far, totally doable just will need a higher density PCB than I've used in the past for these parts.

Open ##4251367