Atmel's ASF support SD card in 4-bit mode.
If you are using ATSAM3 devices it is easy because they have HSMCI
controllers that support 4-bit SD in hardware and there are ready-made
sample applications.

I don't know any Microchip MCU with support for 4-bit SD card in
hardware. The PIC32MZ series has the SQI (Serial Quad Interface) but I
have read the datasheet and could not determine if it is compatible with
SD-Cards.

You could use Atmel's source code for the FAT File System and high-level
SD-Card routines, and implement the low-level hardware functions with
your own bit-banged routines.

Atmel's ASF uses the FAT-FS by Chan, which has an awkward API (f_open,
f_close, f_write, f_read, etc., all of them with arguments and return
values very different from the standard C library). I wrote an
adaptation layer to allow for me to use portable code (open, close,
read, write, lseek, etc.). As a bonus, the buffered functions (fopen,
fclose, fread, etc.) work also, because NewLib is implemented in a way
that if you supply open_r, close_r, read_r, etc, all the other file
functions work seamlessly.
If you use Atmel's code and want to use my routines, just send me and
e-mail.


Cheers,

Isaac



Em 09/11/2015 21:38, James Burkart escreveu:
> I would love some suggestions on either a good SD library (using X16) tha=
t
> allows me to communicate 4-bit, or a resource for flash memory.
>
> I have searched through DigiKey with no luck on flash memory. What I can
> find is crazy expensive and they stock almost nothing.
>
> --
> Sincerely,
>
> James Burkart
> *Filmmaker & Documentarian*
>
> *Burkart Studios*
> 415.738.2071 | Phone
> 925.226.4910 | Fax
>
> *Web:* burkartstudios.com
> *Facebook:* facebook.com/burkartstudios



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