Simon27
Newbie level 5

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!
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!