Sunday, September 9, 2012

Blazing Saddles!

Sometimes the simplest things are the best.

By doing a few simple changes to the SD card library, I've managed to squeeze out a whopping 3x performance out of the SD card reading! I learned that once the card has been initialized into SPI mode it's possible to raise the clock speed A LOT.

Currently I'm setting the clock speed after init to ten times the speed before init. This means a full frame loading in just 2.5 ms and by doing this, I've increased the overall refresh rate by 15 Hz! The card is now reading approximately 614KB/sec!

The card functions with higher speeds, but data gets corrupted along the way. This is probably because the rise/fall times of the resistors in the SD card circuit needs time to switch. With a faster circuit I'm pretty sure I could squeeze out more!



  1. wow, thats pretty awesome stuff.

  2. Yeah, one of the easiest speed improvements I've ever coded! :D

    With 0.6MB/s I'm close to the theoretical max transfer at 1bit, since 4bit has a maximum of 1.7MB/s on this card.
    So I'm very pleased with the results! :)

  3. Just wanted to say that I have been following your blog for awhile. Keep up the good work :)


  4. Glad you like it! :)

    It gets a bit technical and (sort of) away from the topics of pinball sometimes, but I'm documenting all aspects of the build...
    However - will be posting a video soon of the current menu system and gameflow, so stay tuned! :)