Add SPIRAM to WROOM32

[rdagger]

I've built a small handheld project using an older Wemos Lolin32 (no SPIRAM). Unfortunately, after beta testing I realized the urequests class is running out of memory. I tested the code on a newer Lolin32 Pro (4 MB of SPIRAM) and it works much better.

Everything is 3D printed and soldered together. Switching boards would require extensive redesign. I found a post on the ESP32 forum indicating that you can add 4MB of SPIRAM to the ESP WROOM32 chip on my Lolin32.

Does anyone know if MicroPython is compatible with this mod?
Does anyone know of a source to get the IPS6404L-SQ-SPN in the US or if there is an alternative chip available from Mouser or Digikey?

[tve]

I want to do the same and ordered 10x LY68L6400 chips via aliexpress: https://www.aliexpress.com/item/4000700754968.html, but they haven't arrived yet. LCSC is a good alternative source. I figure that if you wire them up just like they're wired on WROVER modules it should work just fine. We shall see
You do need gpio 16 & 17 for that, IIRC, check the schematics. Warning: you do have to make sure that your psram has the same voltage as the flash on your WROOM. There are a couple of variants (e.g. WROOM-32 vs WROOM-32D) and some have 1.8V flash others 3.3V flash. I believe the chip you mentioned is 1.8V and less likely to work with your module... Note also that the gpio are hard-coded into esp-idf, so if you must use different pins you have to edit the source.

[rdagger]

Thanks for your response. Please let me know if it works.
Here's my board. Is it possible to check the flash voltage without removing the shield?

[rdagger]

I found a better implementation of urequests that supports response.iter_lines(). Everything is working great now!

[Roberthh]

Just for interest I upgraded a Wemos Lolin Lite with that PSRAM chip, following the cited instructions. It worked instantly. If you want to do that, better remove the shield cap from the Wroom module and place the RAM on top of the flash chip. They share 6 of the 8 required connection. Removing the cap is not difficult. You just need a sufficient powerful soldering iron. Start at a corner. Solderding the RAM is the opposite. You need a fine tip, good eyes and a steady hand. Even if the latter two a degrading with me, I finally succeeded. But, as said, there is no commercial need to do so, given that ESP32 boards with PSRAM are easily available.

B.T.W.: Compared to that, replacing flash with a larger sized Version is easy.

[tve]

Just for interest I upgraded a Wemos Lolin Lite with that PSRAM chip, following the cited instructions.

Which PSRAM chip? There are two different ones mentioned in this thread.

[Roberthh]

IPS6404LSQ, as far as I can read the numbers. That's the one I could get. Picture attached. I also changed the flash chip. The Wemos lite is not the best candidate due to it's CH340 USB/Serial bridge, which is pretty slow. But it had the flash directly accessible.

wemos lite.jpg (129.11 KiB) Viewed 4419 times

[tve]

Nice mod!