At 07:35 AM 3/23/2011, PICdude wrote: >Hi all, > >Tinkering with a 40x4 LCD. Haven't found a full datasheet yet, but >this is the physical data... >http://www.winstar.com.tw/products_detail_ov.php?lang=3Den&ProID=3D41 > >With the two enable pins and the repeated addressing of the character >positions, I suspect it's just laid out two 40x2 LCDs in one. And I'm >fairly sure I've heard this before somewhere. > >However, I have doubts on the pinout. The pins are labeled in reverse >order (compared to the 16x2, 20x2), but comparing pin positions, >almost all lines (DB0-7, R/W, Rs, Vo) are in the same position, but >the Vdd & Gnd lines are reversed. Is this correct? Or could it be a >datasheet error? I want to be sure before I fry this thing. I've had otherwise identical LCD displays with Vdd and Vss pins swapped. Quick check: put a 1K resistor in series with your 5V supply and just=20 touch to the Vdd & Vss pins while measuring the voltage at those=20 pins. You will see the voltage clamped to about 0.7Vdc if you have=20 the polarity backwards. That's what I did when I got that batch of LCD displays with the=20 reversed power pins to confirm that in fact the pins were swapped. And yes: the 40x4 display that I've worked with is just two 40x2=20 displays in a single package with all of the control lines paralleled=20 together except for the enable lines. dwayne --=20 Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .