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LED Matrix from 8 bit latch

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Newbie level 5
Jul 17, 2010
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I am trying to build a circuit that will run an 8x8 LED matrix. The data for which LEDs should be lit is stored in a 74HC259 8 bit addressable latch.

I think I have got the basic block level circuit worked out (see attached diagram). A binary counter goes from 0 to 7. This produces the address for which the 8 bits of data are stored in the latch.

A 3-8 line decoder decimalises this to activate the current row.

Data is set by pre-setting the counter, which then sets the address for the latch where serial data is entered.

The part I'm trying to figure out is how to wire the LEDs of the matrix between the latch output and the row-enabling decoder. Should there be transistors or some other circuitry to get the current though the LEDs for only a single row at a time? Without frying either the latch or the decoder?

I have never built anything like this before so any help or guidance would be appreciated. Is this circuit even practical?

Nothing is built yet, I'm just trying to sort out the details for what I'll need. I’m hoping to use logic chips - not a PIC!


  • Matrix Block Diagram.png
    Matrix Block Diagram.png
    86.4 KB · Views: 146


How are you going to read the data into the latch. One row at a time, or just having some external hardware/circuitry that is synced to the counter?

One row at a time. The clock input would be cut off, address preset on the counter, and then serial data fed in at it's own speed.

Then the counter is started again.

The plan was that the data would come from an Arduino, without using all of the processor time directly controlling the matrix.

At the moment I can't see any reason why it won't work.

Good luck building it :)

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