AVR-Chat

On Thu, Sep 18, 2008 at 1:36 PM, David Kelly <dkelly@hiwaay.net> wrote:
> Anyone have an idea as to how fast an AVR can read an SD card or CF
> card? Am in need of sustaining 10E6 bits/sec. At first glance this gives
> me 16 clock cycles per byte at 20 MHz. This could work if the timing on
> the memory card is deterministic without periodic pauses, that I don't
> have to buffer in AVR memory, and have interrupts disabled.


Well... Define "read"..  :)

In that video project, I had to stream 30 fps to a color LCD display.
I only actually looked at 16 words of the data from the nandflash, for
the rest of it, I set up the hardware so that the low edge of the read
pin was a read pulse to the nandflash and the high edge of the same
pulse was the write to the display.  So, to do a frame, all I had to
do was cbi and sbi 20,000 times.  While that's tedious to write in
straightline code, it's blisteringly fast.