Oliver, hi, and sorry for my english in advance.
Just bought a 12864B (st7920) lcd from dx.com, and wired it to my arduino (compatible) nano v3.0. When connecting it thru SPI and using your 1.09 library I can use all the demos you provide, but (as you explain) it's a little slow (fps wise). So I tried to wire it thru 8bit parallel, but I get a corrupted screen (some or most of the image it's supposed to show is there, but the rest is... random.). I've checked and rechecked the wiring and just can't find the error.
The two are connected like this:
Arduino --> LCD function --> LCD naming
d5, d6, d7, d8, d9, d10, d11, d12 --> d0, d1, d2, d3, d4, d5, d6, d7 --> db0, db1, db2, db3, db4, db5, db6, db7
d4 --> clock --> E
d3 --> RW --> R/W
d2 --> CS --> RS
GND --> Ground logic, PSB, ground backlight --> GND, PSB, BLK
5v --> vcc logic, vcc backlight --> VCC, BLA
and the constructor used for parallel is
U8GLIB_ST7920_128X64 u8g(5, 6, 7, 8, 9, 10, 11, 12, 4, U8G_PIN_NONE, U8G_PIN_NONE, 2, 3);
in SPI is
U8GLIB_ST7920_128X64 u8g(4, 3, 2, U8G_PIN_NONE);
The only wire I change when testing from SPI (working) to 8bit parallel (garbage) is the PSB from gnd to 5v, and reupload the sketch with the other constructor
And here is a video of what it looks like when running the "graphics" example in parallel:http://www.youtube.com/watch?v=4qIpiHyE36g&feature=youtu.be
What am I doing wrong?