Adding more PSRAM memory chips on T4.1

[Sandro]

Hi all,
in my application (real time audio processing, with many large audio file and complex processing), there is a point where RAM memory is not enough to host audio samples and both SD card and Flash memory chip are unsufficien, haveing "poor" read speed. Two 8MB PSRAM memory chips, that T4.1 can host, are able to guarantee my read performance; but I'd like to provide my Teensy with more than 16MB PSRAM memory.
Hypothesizing to solve electical issues (non-trivial task, I know!) of placing more PSRAM chips (replicating the actual pattern with more chips, parallelizing EMC_24-29 and adding more CS signals), than, I guess: maybe tons of work is still missing to use this additional memory? Has anyone already tried to do something like this?
Thank you

 

[jmarsh]

The idea of adding more chips with additional CS lines won't work; FlexSPI only supports two devices.

The only practical option for more RAM is using the SEMC module (which uses mostly parallel-type memories rather than serial) and for that you'd need to design your own board like this one. You can connect up to four individual SDRAM chips but keeping all the tracks the same length might be a bit of a nightmare.

 

[PaulStoffregen]

4 chips might be possible, but you would need to access 4 additional data pins that aren't available.

 

[BriComp]

I don't know if this helps.

 

[joepasquariello]

Can you say what are your required data rates for both read and write?

 

[Sandro]

Thank all for your replys and your suggestions;
@jmarsh that project is super interesting but (unforunately) far beyond my actual capabilities!
@Paul I hope future Teensy boards will host and drive more powerful PSRAM chips... I'm so hungry of (fast) memory!!
@BriComp it looks Teensy41Memory offers a lot of memory but I cannot find documentation about the code needed, or examples, and access performance;
@joepasquariello: writing is not so critical, I've not a precise requirement, while reading is demanding; I whish to get 16Kbit read in about 100us.

 

[joepasquariello]

@joepasquariello: writing is not so critical, I've not a precise requirement, while reading is demanding; I whish to get 16Kbit read in about 100us.

16Kbit/100 us = 2KB/100 us = 20MB/sec. SD cards can support read at 20 MB/sec, and also write at 20 MB/sec, but if you have to erase, it becomes difficult.

 

[Cviet]

I add a 32m sdram,for machine vision

 

[Sandro]

16Kbit/100 us = 2KB/100 us = 20MB/sec. SD cards can support read at 20 MB/sec, and also write at 20 MB/sec, but if you have to erase, it becomes difficult.

@joepasquariello: sorry for my late replay; In my application, each update() some audio objects open 16 files, read an average of 16KB from each of them, than close all files, using max 1600us of CPU time; this is possible if data is on RAM, not on Flash memory chip, and very far from SD card capabilities.

 

[joepasquariello]

@joepasquariello: sorry for my late replay; In my application, each update() some audio objects open 16 files, read an average of 16KB from each of them, than close all files, using max 1600us of CPU time; this is possible if data is on RAM, not on Flash memory chip, and very far from SD card capabilities.

Is PSRAM fast enough? Doesn’t seem like it would be.

 

[nickleyerm]

Is PSRAM fast enough? Doesn’t seem like it would be.

It's not enough!