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SD Card quad bit object — Parallax Forums

SD Card quad bit object

richaj45richaj45 Posts: 179
edited 2012-09-11 10:22 in Propeller 1
Hello:

I am looking for a SD card driver that uses all 4 bits of the SD interface. I do not need FAT since i plane to only read and write blocks. I.e. 512 byte sectors.

Thanks for any help.
cheers,
rich

Comments

  • RaymanRayman Posts: 14,826
    edited 2012-09-11 09:27
    I don't think one exists because the 4-bit interface is proprietary and they want lots of $$ to let you use it...
  • ericballericball Posts: 774
    edited 2012-09-11 10:00
    I believe this contains the info needed to create a 4 bit interface: https://www.sdcard.org/downloads/pls/simplified_specs
  • lonesocklonesock Posts: 917
    edited 2012-09-11 10:18
    The real issue is the "diminishing returns". Packing 4 bits at a time into longs takes time too. IIRC, I can only get about a 33% speed boost over SPI mode in the prop 1, and that's *if* we force the data pins to take up P0..P3, with the added cost of ~50% larger code size too. Right now I can get ~2MB/s raw data rates from the fsrw block driver, hopefully that is good enough for most purposes.

    Jonathan
  • RaymanRayman Posts: 14,826
    edited 2012-09-11 10:22
    Really, so the 4-bit mode is OK to use now? Definitely going to need that for Prop2 then...
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