julienvoirin Posted October 18, 2007 Report Share Posted October 18, 2007 I ve builded the base PCB of MB6582 of Wilbai ve tried to put a display to J15, but it doesn't display anything. backlight is ok, i connected B+ to Vddthe display is the following : http://cgi.ebay.fr/HD44780-20X4-Character-LCD-Display-with-BLUE-backlight_W0QQitemZ220150773711QQihZ012QQcategoryZ100792QQssPageNameZWDVWQQrdZ1QQcmdZViewItemit works in 4bits mode tell the Chinese guy.My cable is ok, display has been tested with a midibox driven by 18F452, and it works good.I ve uploaded setup_mb6582.hex to the 1st core, ID00000testtone app works too.i tested with another display, same issue : works well with a midibox running a 18F452, don't work with the base PCBAccording to http://www.ucapps.de/mbhp/mbhp_lcd_4bit.pdf i should have a 1k pull up resistor (R80?)Any help welcomeThanks Quote Link to comment Share on other sites More sharing options...
Wilba Posted October 18, 2007 Report Share Posted October 18, 2007 That PDF shows the default wiring on the MB-6582 base PCB... HOWEVER the resistor is connected to the PIC pin AND NOT the J15 pin, it is NOT needed for the LCD.You aren't usng 4-bit mode on the PIC18F452 Core, therefore you have only proved it works in 8-bit mode on the other Core, and not proved that 4-bit mode works for these displays. You can try moving the PIC18F4685 to the other Core, and disconnecting the unused four data wires on the LCD (I am assuming if you've tested it on the PIC18F452 then you must be using a cable with all 8-bit data wires connected). This will test these displays work in 4-bit mode.Also, check connectivity between J15 pins and the PIC pins. Maybe there is a short or a break.Finally, R80 should be mounted for the CAN bus, but it should have no effect on whether the LCD works or not because it should not be connected to J15 at all.... likewise with the diode that connects the CAN bus Tx/Rx pins on port B, these are not connected to the J15 pins and thus not connected to the LCD. Quote Link to comment Share on other sites More sharing options...
julienvoirin Posted October 18, 2007 Author Report Share Posted October 18, 2007 solved : i have pushed the contrast at the maximum and it works ...sorry for disturbance, but thanks a lot for advices, hope it serves to others Quote Link to comment Share on other sites More sharing options...
Davo Posted October 18, 2007 Report Share Posted October 18, 2007 Hmm... having to push the contrast to maximum to get something decent out of it doesn't sound right. Quote Link to comment Share on other sites More sharing options...
julienvoirin Posted October 18, 2007 Author Report Share Posted October 18, 2007 as long as it works ... Quote Link to comment Share on other sites More sharing options...
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