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Known good/bad uSD card types? - Page 3 — Parallax Forums

Known good/bad uSD card types?

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  • evanhevanh Posts: 15,854

    @RossH said:
    "Riddle me this, Batman ..."
    The only difference is the setting of the FLASH DIP switch. I have looked at the schematics of the P2 EDGE, and I can see that the SD Card and FLASH share pins, but I cannot see why this should cause problems with only one SD Card, and not with any other cards.

    Also, with the FLASH switch off the EEPROM's CS pin is disconnected. It can't be accessed so it won't conflict.

  • RossHRossH Posts: 5,458

    @evanh said:

    Also, with the FLASH switch off the EEPROM's CS pin is disconnected. It can't be accessed so it won't conflict.

    I assume you mean FLASH, not EEPROM? I agree it looks as if it should not conflict. And yet it apparently does! But only with one card . I have ordered another card of the same type to see if it behaves the same way, but after that I think I am done - this is taking way too much time, so I will just recommend always booting from FLASH if you need to use the SD card.

    Ross.

  • evanhevanh Posts: 15,854
    edited 2024-01-04 00:24

    Flash is a type of EEPROM. So, yep, I interchange the names as equals when Flash is used as a boot ROM.

    If you do confirm a second Sandisk Ultra misbehaves then I'll order a couple as well. I'll be testing Flexspin SD support with them, to compare. And if they play up there as well then I'll hopefully investigate as to why.

  • RossHRossH Posts: 5,458

    Just another small data point ....

    It occurred to me that it could be the P2 EDGE board that was faulty - perhaps a problem with the FLASH switch, or some leakage between tracks. But I tried another P2 EDGE with exactly the same results. Everything works fine when booted from FLASH, fails every time when the same software is booted from SD.

    Ross.

  • GenetixGenetix Posts: 1,754

    RossH,

    Stupid question but what voltage are you using?

  • RaymanRayman Posts: 14,572

    Ordered some industrial uSD from Mouser today. $16 for 16GB, so not that expensive...

  • RossHRossH Posts: 5,458
    edited 2024-01-04 22:28

    @Genetix said:
    RossH,

    Stupid question but what voltage are you using?

    I power the board (which is on a P2 EDGE Breakout board) from a second USB 3.0 port, so 5v, 1.5A.

  • RossHRossH Posts: 5,458

    My second Sandisk Ultra SD Card arrived. I had expected it would either work, or fail in the same odd way the first one does. But this one is different again - it fails randomly whether the FLASH switch is on or off. I think these cards are just flaky - it may have been just pure luck that the first one seemed to work at all. However, I have neither the time nor the inclination to dig any deeper.

    Catalina's new SD Card plugin (posted on the main Catalina thread) works with every other SD card type I have tried, so in the next release I'm just going to add a recommendation not to use Sandisk Ultras.

    Ross.

  • evanhevanh Posts: 15,854
    edited 2024-01-11 05:31

    Thanks for update. And yeah, I'll prolly not put a lot of effort in myself. All the Sandisk's do seem to be unique controllers.

    EDIT: Ross, I note there is two top speeds listed for Ultra 32GB from different shops: 120 MB/s and 98 MB/s. That suggests the card's controller changed over its production lifetime. Chances are you've now got both variants.

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