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Rafaquasilvaresmasego , 10-13-2025, 05:44 PM

Hello Everyone,
I designing a new SoM board for Image and Audio processing with STM32MP257F MPU but I have some questions.

This will be board is my first design of MPU so i dont experienced with DDR rams. What I should attention for DDR selection also I used STPMIC25APQR for MPU and DDR power and I compared with STM32MP257F eval board. I used BUCK6 output for DDR power but default voltages doesnt writed on the datasheet. Do you think its give some voltage output default or its wait I2C command for gives DDR power? If have an idea pls share with me. 🙂

Unix_Man , 10-14-2025, 12:17 AM

I'm also new to DDR design. I've spent about 5 months in courses to learn DDR hardware design. DDR selection and schematic will be the most easiest part of the this hardware design journey. The most difficult will be layout and routing it. From my understanding, you would need to see the datasheet and application notes of the SoC/MPU which should provide some insights on selecting proper DDR. Also most cases the MPU software tools also contains a selection of DDR which they recommend. For example many of Xilinx's SoCs uses Vivado software tool, in Vivado, you select your SoC/FPGA and it will provide recommended components, such as flash memory as well as DDR2/3/4 memories. Also try to ask the MPU vendor for DDR selection as well. Hope this gives some insights. DDR is very complex, I've reading about it for years and already spent few months to actually learn how to interoperate, DDR is very complex because meany testing needs to be done in expensive verification software as well as hardware. Watch Philips course in advanced hardware design as well as Roberts, it should give a very clear idea how DDR is routed.

Robert Feranec , 10-14-2025, 10:50 PM

if it's your very first design I would recommend to stay as close as possible to the reference design (including using the same components/chips) so initially you can run your board with the software/firmware from the reference boards. Also, I recommend to buy the reference boards, so if you have any questions you can find answer there.
- Voltage output: Output of some PMIC regulators can be set during initialization process by firmware or the PMIC may need to be programmed during production.

Rafaquasilvaresmasego , 10-16-2025, 07:39 AM

thank you very much for your comment and interest 🙏

Rafaquasilvaresmasego , 10-16-2025, 07:47 AM

Firstly Thank you very much for comment and interest.
As your say , I try stay same components but some components status is obsolete so I replaced with the active components. I hope dont face any problem. 😅