Hello FC community, An update on the FreeCalypso handset project: I am still in the process of evaluating candidate LCDs from different vendors. All of the candidate LCD manufacturers I am evaluating are based in Shenzhen, China - that city seems to be the world capital for fast-turn electronic design and manufacturing - and in the present case it is home to a large number of different LCD manufacturers.
The only LCD I have successfully tested so far (as in got to the point of displaying pictures) is the one from Startek, model KD020C-2A - Startek was the first vendor to send me usable sample pieces, and they included a breakout board that made it much easier for me to assemble a working test rig. Here are some pictures of this test rig: https://www.freecalypso.org/members/falcon/pictures/lcd-test-rig/ The test rig consists of the LCD itself, the LCD vendor's breakout board, one of our FT2232D boards for interfacing and a rat's nest of wires connecting the LCD breakout board to the FT2232D board; the whole mess is mounted on a 6x12" sheet of acrylic material with double-sticky tape. The only outside connection to this whole arrangement is USB on the FT2232D adapter board, used for both power and programming: as soon as USB is plugged in, the LCD backlight lights up as it is powered directly from USB 5V through a resistor in series with each LED. I programmed the EEPROM on the FT2232D board with my own USB ID so the connected USB host won't treat it as a serial device (it is not a serial device - I am using the FT2232D chip in the so-called MCU host bus emulation mode, which is completely different from serial or SPI/JTAG), and in order to talk to the controller inside the LCD module and put pictures on the LCD, I run a special test program based on libftdi (published in the freecalypso-hwlab Hg repository on Bitbucket) that issues the necessary LCD controller commands through the FT2232D running in FTDI's MCU host bus emulation mode. The original KD020C-2A LCD had 12:00 viewing direction which we don't want (it is the opposite of the direction from which cellphone LCDs are meant to be viewed), but the sample pieces which Startek sent me are a modified version - it has been modified with some special film that somehow improves the viewing angle. I don't really understand it myself, but most of the test pictures I have tried displaying actually look better on this LCD from the 6:00 viewing direction (the one we want for the cellular handset application) than from 12:00. Overall the picture quality is very good, and this LCD from Startek would definitely make a good choice for our FreeCalypso handset product. It is definitely better than the LCD on the Pirelli DP-L10, and my S.O. says that the picture looks even better than on her Nokia phone. As a matter of due diligence though, I do need to evaluate one other LCD from a different vendor before we officially commit to using Startek LCDs. According to both the LCD datasheet and the vendor's communication with me, the other vendor's LCD is officially made for the 6:00 viewing direction, whereas Startek's LCD was originally 12:00, but then modified in some way which I don't really understand. It is possible that Startek's LCD with their special film is so good that it's even better than the other vendor's LCD made for 6:00, but I need to see both with my own eyes before I can commit to anything. The other vendor in question already sent me their sample pieces, and they are supposed to arrive on Monday California time. But they don't have a breakout board similar to Startek's for their different connector, so I will need to make my own test PCB. I plan on still using an external FT2232D breakout board rather than incorporating the FT2232D into my own test board - this way the test board will be simple enough for me to lay out myself. I'm going to give pcb-rnd a try on this LCD test board - I have previously used gEDA/PCB, but pcb-rnd has been making great progress and might be suitable for doing the actual handset motherboard layout way down the road, so I'm thinking of trying it out for the very simple board. I'm hoping to do this layout some time this coming week, and then it will probably be another 2-3 weeks to actually get the PCB made - but it is needed so we can properly evaluate both LCD vendors and make a fully informed decision. Stay tuned for further updates. Hasta la Victoria, Siempre, Mychaela aka The Mother _______________________________________________ Community mailing list Community@freecalypso.org https://www.freecalypso.org/mailman/listinfo/community
