From: <[email protected]> Reply-To: <[email protected]> Date: Tuesday, January 7, 2014 at 1:50 PM To: <[email protected]> Cc: samer shatta <[email protected]>, yahya tawil <[email protected]> Subject: [beagleboard] interfacing LCD panel to BBB
> > we are trying to interface some cheap LCD panel to the BBB > after checking some OpenSource designs we noted that all of them dont connect > the data and control line from the beagle directly to the LCD . > some designs are adding serial resistors on each line like this one , page #7 > http://www.4dsystems.com.au/new/productpages/4DCAPE-43/downloads/4DCAPE-43(T)_ > datasheet_R_1_4.pdf > > or even more adding a transceiver IC that is not inverting or level-shifting > the signals like the LCD capes made by circuitco , page #21 > http://www.openhacks.com/uploadsproductos/beaglebone-lcd7-reva2-srm.pdf > > so please , can any one explain those designs to me and how to calculate those > resistors if they depend on some panel parameters > i have already modefied a DTO and loaded it and successfully fried a LCD panel > that was directly interfaced to the beaglebonebBack The resistors are for impedance matching and to prevent reflections on long signal lines. These resistors have nothing to do with the make of the LCD, but are just standard practice when connecting high speed signal lines that are more than a few inches long. The resistors are used to slow down the signal transition and this eliminates refections on the signal lines. After you build the board, use an high speed oscilloscope to measure the signal quality. If you observe overshoot, then increase the resistor value. If the transitions are rounded, then decrease the resistor values. Regards, John > > > thanks in advance > > -- > 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/groups/opt_out. -- 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/groups/opt_out.
