If I may ask, why the interest in the nibble mode? Reconstructing the data loses almost all of the speed gains, and costs more code and pins. IIRC, when I looked at this, if I unrolled all loops I could maybe get a 30% speed boost.
lonesock: As I understand it, the access is considerably faster which is why all the cameras, etc use this mode. Whether this will translate to faster access by the prop I am not sure, but perhaps it is worth investigating. As they say, nothing ventured, nothing gained.
BTW: This interface is also relevant to those that wish to place objects and load them from upper EEPROM, not just SD cards. And its relevant to the various languages such as spin, pasm AND C, Basic, Forth, etc, etc.
If I may ask, why the interest in the nibble mode? Reconstructing the data loses almost all of the speed gains, and costs more code and pins. IIRC, when I looked at this, if I unrolled all loops I could maybe get a 30% speed boost.
Jonathan
30% may be critical. I am playing with wav files play routines now and it seems my SD card speed is on the border. It cannot play faster than about 50 kHz sample rate. And I had to use 2 buffers 1 kB each, 512 bytes was too short to play without glitches.
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Jonathan
30% may be critical. I am playing with wav files play routines now and it seems my SD card speed is on the border. It cannot play faster than about 50 kHz sample rate. And I had to use 2 buffers 1 kB each, 512 bytes was too short to play without glitches.
For video, or similar, I can see the speed bump helping a bit.
Jonathan