Real time clock ICs


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  1. #28
    Join Date
    Sep 2004
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    Hi Eng4444,

    I wasn't trying to make you nervous by asking for drawings and code work. It just makes it easier to figure out what is going on. At first glance of the schematic I see the following:

    1) I think your LCD data lines are wrong. You should tie lines DB0 thru DB3 to ground then starting with DB4 tied to RA.0, DB5 to RA.1, DB.6 to RA.2 and DB7 to RA.3. The Read/Write pin on the LCD needs to go to ground. I tried to get the Datasheet (don't you just love it?) from Winstar but you have to signup with them to get these and I'm waiting to hear back from them so I can verify these connections when using a 4 bit bus. The couple of types of LCDs and VFDs I use start with DB4 when using 4 line bus connections.

    2) Pin 3 on the DS1307 needs to go either to a backup battery or tied to ground if you're not using the battery.

    3) You should change the pull up resistors on the SCL and SDA lines from 10K to 4.7K.

    4) I realize you had a hard time getting this drawn out but I don't see any capacitors. You need a .1uF on the power supply lines of EACH device as close to the device as possible. You should also have a .1uF and a 10uF on each side of the voltage regulator if that's how you are powering this project.

    You did mention that you have a potentiometer connected to the contrast pin of the LCD. I didn't see that on the drawing.

    Start with the above and try the program above. This may just take care of your problem. I have not sat down with the code. I trust that you have checked and rechecked that. Keep in mind that a single character wrong somewhere can keep it from working correctly. Someone recently had LCBOUT instead of LCDOUT. Big difference!

    Good luck!

    BobK
    Last edited by BobK; - 7th June 2006 at 19:56.

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