And the next follow-up!
I have got the LCDs working. It was actually quite easy once the circuitboard was made. The Nokia 6555 has two LCDs, one 320x240 16M colors and one 128 x 160 pixel with 262k colors. Both have the same electrical interface, except for the backligth leds and The P_select pin.
I broke my LED driver when I connected the smaller LCD to my circuit. After a little measuring, I found that the pins for the second led pair were grounded. I soldered off the boost converter diode and connected the small LCD up. Even though the backlight was off, I could see it reseting and clearing the display, so it is safe to say that the LCD's interface is identical. Ofcourse, all of this is quite evident if you look at the nokia 6555 schematic.
I made my circuit with a PIC18F25k20, mostly because that was the only chip I had that still worked with a voltage of 1.8V. The LCD logic is driven with 1.8V and I didn't feel like adding levelshifters to the circuit. I took this opportinuty to test Microchip's USB -> Serial converter (MCP2200, wich actually is just a preprogrammed PIC18F14K50). It worked fine. I had to add levelshifting transistors between it and the main chip.
The LCD's driverchips are quite nice and easy to use. I made a library to draw basic shapes. When you find bugs, feel free to correct them and please, post the corrections here
. The routines are by no means optimised, to clear the whole display takes about a half second (with Fosc = 16MHz). This is mostly because the LCD is quite big for this little PIC. Line and circle routines I scavanged from wikipedia. The text printing function is just a quick test, it will be completly rewritten.
In summary, the LCDs of a Nokia 6555 ar easy to use and quite cheap. And the best part is, you get two from one phone! The only hard part was to find the correct connectors.
Please post your comments and ideas. I've attached some pictures.
Edit: If you are wondering about CONN_10, its for Nokia 6100 type LCD