supraanimo Posted February 25, 2007 Report Share Posted February 25, 2007 Hey All,I seem to be having problems with some 40x2 lcd modules I have purchased. One is based on the KS0066 controller and has model number TM402C from Tianma. The other is the Wintek WM-C4002M-1yly but I don't know its controller. The data sheet for the Tianma model is here http://docs.bgmicro.com/pdf/lcd1025.pdf and a sheet describing a similar lcd from wintek is here http://www.wintek.com.tw/ModuleList.asp?LcmType=&DispType=CHARACTER&ModuleNo=WM-C1602M-1GLYfI also have a 16x2 lcd that works when connected, however when I connect the 40x2 displays nothing will show up. Could this be due to the displays requiring a negative 0.3V on V0, as described in the tianma module. Or do these displays need negative contrast voltage? Quote Link to comment Share on other sites More sharing options...
TK. Posted February 25, 2007 Report Share Posted February 25, 2007 Hi,do you see a gray/black line when the LCD is powered and not initialized?This would indicate, that the contrast voltage is ok. If not, this Wiki page helps: http://www.midibox.org/dokuwiki/doku.php?id=troubleshooting_lcd_displaysBest Regards, Thorsten. Quote Link to comment Share on other sites More sharing options...
supraanimo Posted February 25, 2007 Author Report Share Posted February 25, 2007 I see the black line when I connect my 16x2 ( which I thought stopped working but then realized I broke the Enable line), however when I connect either 40x2 I see nothing. I was able to find this datasheet on the Wintek LCD http://www.cyfronika.com.pl/dokumentacje/wmc4002.pdf however I see nothing about needing a negative contrast voltage. The data sheets say VDD-V0 for both should be 4.5V. With VDD at 5V that would mean V0~0.5V . I just don't want to destroy the module with a negative contrast voltage ( or anything else for that matter). Quote Link to comment Share on other sites More sharing options...
Lall Posted February 26, 2007 Report Share Posted February 26, 2007 I more read the datasheet as VDD is typical 5V and VO as well.Looks to me like you have a positive constrast LCD...Best regards,Lall Quote Link to comment Share on other sites More sharing options...
supraanimo Posted February 26, 2007 Author Report Share Posted February 26, 2007 Thanks for reading the datasheet Lall, however I can't see any reason why the 40x2 displays won't work they can't both be dead (or can they?). And yes my core is working fine, I can get the 16x2 to work fine. I will try testing everything out when I get the chance perhaps I swapped some cabling somewhere. If anyone else has any ideas, let me know. By the way, would placing a negative contrast voltage on the LCD damage the controller at all, were these controllers designed to handle it?Sincerely,JJC Quote Link to comment Share on other sites More sharing options...
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