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Thread: 16x2 LCD showing two lines of Boxes

  1. #21
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    Quote Originally Posted by ojd233 View Post
    I checked this with a 10K resistor but still no change. When you said it is the same as the download layout, I tried a 22k(that's what I am using from download socket to the 20m2) to see if that did anything, but still not working.
    Actually, I don't recall having said exactly that, but, as Hippy pointed out the 10k pulldown resistor needs to be on the PICaxe side of the 1k inline resistor. So technically speaking the resistor layout is the same as the download circuit, but the values are not. I would NOT suggest using a 22k resistor between the two ICs as it's too high in value. You really need to try the 10k to ground (on the PICaxe side of the 1k resistor) and leave the 1k between the ICs as per Hippy's example. Did you try that? If so, then as Hippy pointed out, to help further, the folks here are going to need some decent photos of the top and bottom of your PCB to see if we can spot any additional issues. The fault could be anywhere.

    A really good place to start is, with the power off/disconnected, put your multimeter into a low ohm range, connect one multimeter probe to the input ground (negative) connection, and then use the other probe to check ALL of the component pins/leads that should be connected to ground. All of these should read dead short. Then, connect one probe to the Vcc (power/positive) input and use the other probe to check it correctly feeds the 5V regulator. Then repeat this process but use the 5V output of the regulator as the new reference and ensure correct connection for the applicable components to the supply rail. That's probably the simplest way to check rail and ground integrity. You can then test the individual signal/data connections.
    Last edited by darb1972; 11-01-2018 at 19:59. Reason: Brain Farts. Lots of them. Still yet to have coffee.
    Darb

  2. #22

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    I haven't yet tried the 10k on the PICAXE side of the boards. If this was the case, would it be creating a voltage divider? If so I think that may be a cause of the problem as I have both resistors on either side the FRM010 chips input pin. If this doesn't work Ill use the multimeter and get some pictures.

    Thanks for the hep so far! I will try this out tomorrow and see if there is any progress
    Last edited by ojd233; 11-01-2018 at 21:12. Reason: Mistakes were made

  3. #23
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    Quote Originally Posted by ojd233 View Post
    I haven't yet tried the 10k on the PICAXE side of the boards. If this was the case, would it be creating a voltage divider?
    Yes it would.

  4. #24

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    Looking at the voltages of the pins on the LCD, only 2(Power), 4(RS) and 11(DB4) are high, all the rest are low. Does this make any difference. I tried the 10K to ground and the 1k inline, but that still doesn't work. The voltage on the power is reading 4.95V. Then the other two are reading 5.05V.
    Last edited by ojd233; 18-01-2018 at 13:08.

  5. #25

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    [Update] After looking at the connections to LCD, I saw a pin that looked unproperly soldered. I redoldered it and it turns out that was the problem. It displayed what was needed on the screen. Thanks for all the help

  6. #26
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    Great news! Well done. Often it's the simplest things that cause the problems. All too often we can (including myself) look past these things and think the problem is the result of something more complicated. This then makes finding the original cause of the issue even more difficult (because everyone assumes that the simple stuff has been checked and eliminated).

    When things don't work as expected or a fault arises (either on something I've created or something I have to repair/troubleshoot), I'll start from scratch, checking ALL the basics first. After nearly 30 years of technical work involving all manor of electronics, on the odd occasion when I've "dived in" at the deep end and failed to check the basics the result has been time wasted looking past what should have been a simple fix.

    Anyway, great result. Glad it's sorted out.
    Darb

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