Chris, My LCD driver should be able to handle display with more than one Enable line. Please take a look the code from the git repo: https://github.com/piranha32/IOoo You will find a simple example driving 4x20 characters display in examples/TestLCD.cpp. Modification for 4x40 characters should be simple: add one more Enable line and increase number of characters in the line when you instantiate HD44780 object .
j. On Tue, Aug 19, 2014 at 7:58 AM, <[email protected]> wrote: > I have a pretty standard 4 x 40 character LCD display that I'm trying > to use from my BBB. > > I already got the BBB working OK with a 4 x 20 character display using > the connections and Python code described here:- > > > http://www.thebrokendesk.com/post/writing-to-an-lcd-screen-with-the-beaglebone-black/ > > An excellent article and I found it quite easy to follow and make it > all work. > > > However getting my 4 x 40 character display to work is proving > difficult. The 4 x 40 display is essentially two of the display > controllers in the 4 x 20 display working together. The hardware > interface is the same except that there are two 'Enable' lines, one > for each of the two controllers. > > When I try to use my 4 x 40 display (initially with just 'Enable 1' > connected and the other tied to ground) I just get the first eight > characters and then a line of faded/ghost splodges. Try as I may I > can only get to display on the first line of the display and the first > 8 characters. > > If I ask for 5x10 bit characters instead of 5x8 then I get nothing at > all. If I set two-line mode I just get a few faded/ghost characters. > If I toggle the enable2 bit instead of enable1 leaving everything else > the same then I get nothing. > > > My 4 x 40 character display is like this one:- > > > http://www.buydisplay.com/default/40x4-lcd-module-datasheet-commands-arduino-pinout-hd44780-black-on-yg > > There is documentation at the bottom of the page including some sample > code. The sample code is for an 8-bit microprocessor connected direct > to the LCD but, in the main, looks as if it does basically what my > code does except for some very odd loops but I think they may just be > 'left overs'. > > The manual for the 4 x 40 display itself doesn't say anything about > software for it or how the two enable bits need to be used. The > manual for the LCD controller is, of course, just for a single > controller, so doesn't deal with the dual-controller. > > > I think either:- > I have a faulty display or there is some subtle hardware > requirement that I'm not fulfilling. > > or:- > There are some software requirements or extra command sequences > required to manage the two display drivers. > > > Does anyone know of any BBB code specifically for a 4 x 40 display? > Or even code for other SBCs for this sort of display. I can find > various references to such things but they're nearly always "how do I > adapt the 4 x 20 code to work with the 4 x 40 display" without any > actual code/changes. > > Any/all ideas would be much appreciated. > > -- > Chris Green > ยท > > -- > For more options, visit http://beagleboard.org/discuss > --- > You received this message because you are subscribed to the Google Groups > "BeagleBoard" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > For more options, visit https://groups.google.com/d/optout. -- Given a choice between two theories, take the one which is funnier -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
