PSRAM on Teensy 4.1

gevietor

New member
Today I tried to solder PSRAM chips (APS6404L) onto a Teensy 4.1 board. Both chips did not work, but seem to be defect. The following error messages were reported while testing the memory:

First Chip error Message:
15:17:05.580 -> EXTMEM Memory Test, 8 Mbyte
15:17:05.580 -> CCM_CBCMR=B5AE8304 (88.0 MHz)
15:17:05.580 -> testing with fixed pattern 5A698421
15:17:05.907 -> Error at 70000000, read 18098001 but expected 5A698421

De-soldering the first one and soldering the second one onto the same (small) pad on the Teensy.

Second Chip error message:
17:39:11.481 -> EXTMEM Memory Test, 0 Mbyte

I tested the Teensy 4.1 before soldering anything. It showed no defect and error.

I recently soldered PSRAM Chips from a different manufacturer onto another Teeny 4.1 board. This work without any problem.

Any idea or similar experience?

Thanks

Georg
 
I have a working Teensy with a recently soldered PSRAM. I have not used it in an application.
How do you run the test?

Regards,
Greg
 
Any idea or similar experience?
Some recurring issue is Flux or other residue/issue needing to be fully cleaned as appropriate to Flux in use, with good solder connects in right orientation.

Usually high % Isopropyl cleaning and then dried well before powering.
 
Use this sketch :
Loaded and running. It does not complete, but it does appear to successfully run many of the tests:
Start:
EXTMEM Memory Test, 8 Mbyte
CCM_CBCMR=B5AE8304 ( MHz)
޼Utesting with fixed pattern 5A698421
testing with pseudo-random sequence, seed=2976674124
testing with pseudo-random sequence, seed=1438200953
testing with pseudo-random sequence, seed=3413783263

testing with fixed pattern F0F0F0F0
testing with fixed pattern FF00FF00
testing with fixed pattern FFFF0000
testing with fixed pattern FFFFFFFF
testing with fixed pattern 00000000

And it stops as above. There should be a serial print after the last fixed pattern test, but it never happens.

Regards,
Greg
 
Loaded and running. It does not complete, but it does appear to successfully run many of the tests:
Start:
EXTMEM Memory Test, 8 Mbyte
CCM_CBCMR=B5AE8304 ( MHz)
޼Utesting with fixed pattern 5A698421
testing with pseudo-random sequence, seed=2976674124
testing with pseudo-random sequence, seed=1438200953
testing with pseudo-random sequence, seed=3413783263

testing with fixed pattern F0F0F0F0
testing with fixed pattern FF00FF00
testing with fixed pattern FFFF0000
testing with fixed pattern FFFFFFFF
testing with fixed pattern 00000000

And it stops as above. There should be a serial print after the last fixed pattern test, but it never happens.

Regards,
Greg
Ooopps, I had the IDE set for "Smallest Code". I redid with "Faster". Now it works perfectly:
EXTMEM Memory Test, 8 Mbyte
CCM_CBCMR=B5AE8304 (88.0 MHz)
testing with fixed pattern 5A698421
testing with pseudo-random sequence, seed=2976674124
testing with pseudo-random sequence, seed=1438200953
testing with pseudo-random sequence, seed=3413783263
testing with pseudo-random sequence, seed=1900517911
testing with pseudo-random sequence, seed=1227909400
testing with pseudo-random sequence, seed=276562754
testing with pseudo-random sequence, seed=146878114

testing with pseudo-random sequence, seed=85016565
testing with pseudo-random sequence, seed=1427530695
testing with pseudo-random sequence, seed=1100533073
testing with fixed pattern 55555555
testing with fixed pattern 33333333
testing with fixed pattern 0F0F0F0F
testing with fixed pattern 00FF00FF
testing with fixed pattern 0000FFFF
testing with fixed pattern AAAAAAAA
testing with fixed pattern CCCCCCCC
testing with fixed pattern F0F0F0F0
testing with fixed pattern FF00FF00
testing with fixed pattern FFFF0000
testing with fixed pattern FFFFFFFF
testing with fixed pattern 00000000
test ran for 37.15 seconds
All memory tests passed :)

Regards,
Greg
 
I have a working Teensy with a recently soldered PSRAM. I have not used it in an application.
How do you run the test?

Regards,
Greg
Thanks. I have tested the Teensy with the sketch from Paul Stoffregen.

Also thank you all for the suggestions and hints. I re-soldered all pins (in particular D1 and D2) and carefully cleaned the board. To no avail. The only explanation I have is that the PSRAM chip has a defect, as my other Teensy does work without any problems.
 
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