Need help 'Constructing LED Dot Matrix using PIC18F452'!

Discussion in 'Embedded Systems and Microcontrollers' started by EnginiusXIII, Oct 14, 2007.

  1. EnginiusXIII

    Thread Starter Member

    Oct 2, 2007
    21
    0
    Currently I have an assignment constructing LED blinking system using PIC18F452 and my idea is to construct LED Dot Matrix system using PIC18F452.
    However, I'm stuck during the process of constructing the Dot Matrix:p. Could anyone help me on how to construct 8X8 Dot Matrix using LED and I want to control every single LED at will using MPLab Programme? Is that possible:confused:? If not, is there any recommendation?

    All I need is the circuit diagram of a PIC18452 connecting to 8X8 LED.
    Thanks in advance!:)
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Connect them up in an 8x8 grid.
    For each of the 8 rows, connect all of the anodes together.
    For each of the 8 columns, connect all of the cathodes together.

    You can control each of the 8 columns with one 8-bit port, and the 8 rows with another 8-bit port.

    Supply current to only one row or column at a time, while sending the bit pattern that should be displayed to the column or row from the other port. If you cycle between the rows/columns fast enough, the flicker will not be apparent.

    You will need something that can source and sink current. Your LED's will probably not tolerate more than around 15-20 mA's, but will be very dim below 10mA. Your PIC can source/sink up to 25 mA, but if more than one LED needs to be turned on, that won't be enough. I suggest looking at something like a ULN8003 or ULN8004 "Eight Darlington Pairs" for the current sinks. Your PIC can turn those on and off. There are current source IC's specifically made for LED displays, but I can't recall a number off the top of my head.
     
  3. EnginiusXIII

    Thread Starter Member

    Oct 2, 2007
    21
    0
    Cool. Thanks a lot for the info. Now I can finally get my hands on it.
     
  4. mindthomas

    New Member

    Mar 9, 2008
    4
    0
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