What RAM types can i use in STM32F4 100-pin packages?

pmarques · ‎2013-04-30

Posted on April 30, 2013 at 11:37

Hello,

after reading and reviewing 1 dozen times the RM and app notes, i could not come to a clear conclusion on what type of RAM i can use in STM32F4 100-pin packages. The more clear and detailed info was for NOR flash and NAND flash but no certains about PSRAM or SRAM, even being stated in the RM as being possible to use them in multiplexed mode.

Can i really use PSRAM or SRAM chips with 100-pin packages? If so, the PSRAM/SRAM chip should be specific (i'm asking this because i looked the specs of a bunch of them and i never found any kind of NADV line, i suppose, needed for multiplexing)? Is there any example i can check?

#stm32f4

waclawek.jan · ‎2013-04-30

Posted on April 30, 2013 at 12:54

I doubt you will find a SRAM/NOR memory which interfaces directly to a multiplexed address-data bus. Waferscale (WSI) used to make FLASH(EPROM)/RAM/PLD combos which provided such interface (to couple seamlessly to '51), but they're discontinued for maybe a decade now (incidentally, it was ST who bought them, but that's another story).

Normally, you are supposed to add a simple '573-style latch to capture the lowermost addresses.

JW

jj2 · ‎2013-04-30

Posted on April 30, 2013 at 18:24

Believe that which Jan's shared here will be of great benefit - you/others. Acquiring WSI data will aid your understanding - getting a part (if possible) or an eval board - even better. (e-bay or ST - if still carried)

As he states - we used WSI w/Zilog & 8051 - iirc there were also some security features. Simpler designs back then will better detail proper/appropriate signal management than that done in newer (better?) MCU manuals.

Another approach is via low-cost CPLD - which can mimic latch approach described - and provide added functions which may assist/enhance. And - w/in CPLD and FPGA fields you may find RAM already mounted/far more ready for your ''harness'' to MCU. I'm not suggesting this for production - instead targeting your experimenting/development - so that you ease & speed that effort...

Almost always best to ''crash/burn'' via demo boards - than to ''scrap'' custom pcb... (do not ask - how I know...)

BTW - think its great that you made time/effort to really study manual. Too often - that aspect of the job is neglected - little good results. Believe you're on good path...