Unable to use PSRAM on Teensy 4.1

[Jamewi]

Using the test program from https://github.com/PaulStoffregen/teensy41_psram_memtest/blob/master/teensy41_psram_memtest.ino

Running the program on a bare T4.1 (no other connections, and it's new out of the box), I just see

EXTMEM Memory Test, 0 Mbyte

The RAM chip I have is an ISSI
IS62WVS5128FBLL-20NLI-TR (https://www.mouser.be/ProductDetail/870-62WS5128FBLL2NIT)

Any ideas? I am confident about the soldering, and I've repeated the test with a 2nd memory chip. Maybe the chip is not compatible? In that case, which chips *are* compatible (especially in the 8mb size)? At least here in Europe, I haven't had any luck finding the ones mentioned on the official page https://www.pjrc.com/store/psram.html



thanks!

 

[mjs513]

Not 100% sure that chip will be compatible. A red flag for me from the data sheet shows the maximum clock on that chip is only 20 Mhz. You might want to check this post out: https://forum.pjrc.com/threads/61399-Teensy-4-1-flash-psram-usage?p=243765&viewfull=1#post243765.

You might check this link out: https://github.com/TeensyUser/doc/wiki/Flash-Memory#teensy-41-qspi-flash-and-psram-pads. It shows a vendor in Germany as well as other vendors.

 

[PaulStoffregen]

At least here in Europe, I haven't had any luck finding the ones mentioned on the official page

EXP Tech in Germany has the correct chip in stock.

https://www.exp-tech.de/en/platforms/teensy/9947/psram-chip-for-teensy-4.1

And FWIW, your soldering looks excellent. But that ISSI chip just won't work.

 

[Jamewi]

Excellent, I think it's case closed here. Thanks for pointing to the Wiki and Exp-tech; order on the way already!