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Topic: Problem with GLCD (Read 717 times) previous topic - next topic

countsoundlight

Hey guys!

I have a problem. I have connected my glcd (https://www.sparkfun.com/products/710?) to my Arduino Mega 2560 according to Panel A (http://playground.arduino.cc/uploads/Code/GLCD_Documentation.pdf) , this is my datasheet (http://www.sparkfun.com/datasheets/LCD/ks0108b.pdf). Basically my problem is that when I twist the potswitch the contrast changes but all the pixels stay black. I'm using the glcd v3 and have uploaded "HelloWorld" from the examples that came along the library. Here's my video on my problem: http://www.youtube.com/watch?v=DVOO2jN0bdg

Thanks guys!

bperrybap

The pixels working and the backlight working is a good sign.
It means the backlight is hooked up correctly and the contrast pot is wired in correctly.

More than likely a wiring error or wires not making proper connection is causing the issue.
What is connected to the GLCD reset pin (glcd module pin 14) ?
It should be connected either to the Arduino reset pin or to +5v.

Run the diag sketch down in the glcd examples and post the output from the serial port here.
Also, if you can take some clear close up photos so I can see where all the wires go
and be a second set of eyes to verify wiring.

Those two will be a big help in figuring out what the issue is.

--- bill

countsoundlight

Thank you so much, I did not now that reset had to be hooked up to 5v because I read through the arduino cookbook and its left blank at the one where it says reset and to arduino mega. Thanks man!

bperrybap

#3
Feb 09, 2013, 09:44 pm Last Edit: Feb 09, 2013, 10:04 pm by bperrybap Reason: 1
The ks0108 reset line is an active low line. (when low, the ks0108 module is held in reset)
It needs to be high for normal operation.
However, while connecting it directly to 5v works for most glcds, it doesn't work for some as
some ks0108 glcds do not self reset on power up and and need a H->L->H pulse on their reset line
to properly reset.

Read the notes about the glcd reset pin on the ks0108 playground page
http://playground.arduino.cc/Code/GLCDks0108
The tables and text show how to wire up the glcd reset line.
Don't miss the special note I wrote about it in the section: GLCD reset pin NOTE

-- bill

countsoundlight

Thanks for the advice!

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