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Query regarding project;; imp

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Newbie level 6
Jan 13, 2006
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I am a student of BE 4th yr EC branch.i am designing final yr project of PIC based LCd oscilloscope in which we are using PIC 16f876 microcontroller & HD44780 (LCD) for display purpose.The input to PIC is on pin 2 i.e. port A RA0 pin.This system can have atleast 5 inputs . Now we are facing problem with LCD initiallization & programmer circuitry.So please guide us how to proceed as the subject is somewhat new.
thank you.

shailendra kumar singh

Hi Sailendra,
As per my understanding of your question you are left with just 5 pins to interface the LCD on PORTA and the rest of the pins are used up in your project isn't it. Well I think you can still interface the LCD but the minimum interface would need atleast 6 pins of the port. One for the R/W one for the RS (Register Select)
and 4 pins for the 4-bit interface mode of the LCD. Now as you are left with just 5 pins make r/W pin grounded as LCD is used in your case only as the output device. So you are left with 5 inputs and 5 pins left to interface, so that solves your problem. But the 4-bit initialization of the LCD can be a bit tricky w.r.t the time delay required to give a stable data, if this is messed up with then the output can be gibberish.



Do you have Hitachi 44780 datasheet ? If yes follow the code as it is on page 46 or 47 depending on whether you are using 4 bit or 8 bit connection.

Follow the signal timings. E should change from high to low after the data (pls double check) has stabilised. The key part is initialising the LCD display and you have to follow the steps as given on page 46 and 47. Give long delays initially between command as time delay must be observed during intialisation which later can be optimised.

It took me one whole day to get the LCD interfaced including generating special characters. Also take note of contrast.


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