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Ahmed
Joined: 07 Mar 2006
Posts: 19
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| Modify LCD & Keypad Driver |
 Posted: Tue Mar 07, 2006 3:39 pm |
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I had project including a keypad and LCD with PIC16F877. I'm trying to use the LCD and Keypad Drivers but both of them were connected to different ports from the one specified in the driver code.
The pins are connected to different ports (i.e: LCD pins half of them connected to port B and the other half to port A). Although, the code was written depending on having all pins on the same ports as, I understood; therefore, please advice, if anybody had any idea how to make it work without doing a massive modification in the code.
Thanks for your Cooperation. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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Ahmed
Joined: 07 Mar 2006
Posts: 19
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| Posted: Tue Mar 07, 2006 5:21 pm |
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Thanks a lot,, I think <Flex_LCD.c> is one I was looking for. I still got two questions for you if you don't mind:
1- I couldn't understand your constrain about connecting Pull up resistor while using PIN A4? I had RS connected to PIN A4 and i already made the PCB. (any software suggestion would be great)
2- Actually I'm using 4x20 LCD and i read that you will not send your modified version to PM anymore but I’m trying my luck 
Anyways thanks for your advice. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Mar 07, 2006 5:40 pm |
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On most PICs, pin A4 is an open-drain output and requires an external
pullup resistor if you want it to be able to put out a logic high level.
LCDs do have a built-in pullup on the RS pin, but it can be a weak
pullup, such as 100K. If so, the rise time might be too long.
The LCD driver could be adjusted for this by increasing the delay
time after the output_high(RS) statement. You could look at the
RS signal on your oscilloscope to check this.
Ideally, you would add an external 4.7K pull-up to pin A4 on the PIC. |
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Ahmed
Joined: 07 Mar 2006
Posts: 19
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| Posted: Tue Mar 07, 2006 5:59 pm |
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| Thanks alot that was really helpfull. i have test all of this and i'll post the results ASAP |
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Ahmed
Joined: 07 Mar 2006
Posts: 19
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| Posted: Wed Mar 08, 2006 1:48 pm |
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"PCM Programmer" actually I’m using a powertip LCD, sorry for not mentioning this before but I though it was using HD compatible controller .Finally, I realized that it uses Samsung S6A0069X.
I found your modified CCS LCD driver for the Samsung controllers but I was wondering if you have Flex_LCD420 driver for Samsung controllers.
Thanks a lot for your cooperation. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Wed Mar 08, 2006 2:08 pm |
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| No. If it needs modifcations, you'll have to do it. |
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