Dr Jefyll wrote:
ArnoldLayne wrote:
Unfortunately, the link to the schematics seems to be dead.
If this can't be resolved then I'll upload the schematic myself. I'm out of town right now but have a copy on my machine at home.
Personally I find the VIA-SPI idea very appealing. It`s just a small amount of hardware, judiciously applied, and it solves the only problem not soluble by software -- namely, the bottleneck on transmission of the datastream itself.
-- Jeff
I have to look up where I stored it, but you can use the VIA to actually easily use for SD-Cards with only a small variation: an additional output to XOR the shift out register. Make sure the last BIT shifted out is always 1, and before you shift out the byte, if the first BIT shifted out is zero, invert the output with the XOR, and also XOR the output BYTE, then shift it. This way you can also work with SPI modes that expect the data on the leading clock edge (and not the following as the VIA/CIA shift registers usually do).
André
_________________
Author of the GeckOS multitasking operating system, the usb65 stack, designer of the Micro-PET and many more 6502 content:
http://6502.org/users/andre/
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