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using utp cable for data and power for a CFAH2004d LCD Caracther display

abadell

New member
Hi, I'm using two utp cat 5e cable for data and power for a CFAH2004d LCD Caracther display. This cable is conected to my display and to a control pcb microcontroler board (atmel at8952). The cable is aprox 2 mt long. The problem is the caracthers in the display are showed in incorrect form. I do not know the reason for this behavior. can you pleae help me?

PD. Sorry for my bad english.
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CF Tech

Administrator
Does everything work if you connect it directly, without using the UTP? Make sure that works first. Assuming a direct connection works, it could be many things.

You might start with a capacitor (1uF in parallel with 100uF) at the LCD end of the cable across power and ground.

You might put a 50Ohm resistor in series with the E line at the processor end.
 
The cable is aprox 2 mt long.
With a cable that long, there is likely to be a lot of crosstalk between the signals, especially since they are ground referenced (not differential). It would be best to put the 8 data bits on one cable, and the control bits + power in the other cable. Use 2 wires for ground, one paired with Vdd, the other paired with Enable signal. You will probably need to use a delay before and after each transition of Enable, to allow the other signals to settle.

Its possible that there is too much ringing (signal bounce) for it to work with a long cable, thats what the 50 ohm series resistor is trying to reduce. The only way to see what the real problem is to use a scope to view the signals.
 
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