6 x 6 dumb led display

[alfa88]

I have made a 6 X 6 led matrix and am trying to figure out how to drive it. My 1st thought is to use hex d type flip flops for the X and Y. The problem is that to get them scanning I'd have to one shot the reset line as well as connect the output of the last stage to the input of the first stage once it is scanning. Any thoughts would be appreciated.

 

[ericgibbs]

I have made a 6 X 6 led matrix and am trying to figure out how to drive it. My 1st thought is to use hex d type flip flops for the X and Y. The problem is that to get them scanning I'd have to one shot the reset line as well as connect the output of the last stage to the input of the first stage once it is scanning. Any thoughts would be appreciated.

hi,
Have you considered shift registers for scanning.
A 6 *6 is a unusual array format, an 8*8 would give a 'better' character.
and more options.

 

[alfa88]

dumb led display

That's what I'm doing. I am using a 74hc174 ,cascaded, with the final output looping back to the 1st. input for the 'X' axis and the identical circuit for the 'Y' axis with the exception of the clock. The 'X' clock is provided by a 555. The 'Y' clock is provided by the output of the last 'X' stage. The problem is that to get the whole thing scanning not only do I have to hit the reset I have to connect the output of the final stage of the 'X' to the input of 'X's' first stage once the scan starts . The reason for the odd 6X6 configuration is that I am using a "Lite Brite" screen as a mask and 36 leds fit nicely. I have no intention of wiring it up to a computer I just want it to be a stand alone display. That's why I am calling it dumb.

 

[ericgibbs]

That's what I'm doing. I am using a 74hc174 ,cascaded, with the final output looping back to the 1st. input for the 'X' axis and the identical circuit for the 'Y' axis with the exception of the clock. The 'X' clock is provided by a 555. The 'Y' clock is provided by the output of the last 'X' stage. The problem is that to get the whole thing scanning not only do I have to hit the reset I have to connect the output of the final stage of the 'X' to the input of 'X's' first stage once the scan starts . The reason for the odd 6X6 configuration is that I am using a "Lite Brite" screen as a mask and 36 leds fit nicely. I have no intention of wiring it up to a computer I just want it to be a stand alone display. That's why I am calling it dumb.

hi alfa,
I see that you have configured 174's as a shift reg, rather that using a 'ready' built ic.

It would help if you could post a sketch of what you have built so far.

 

[Nigel Goodwin]

I have made a 6 X 6 led matrix and am trying to figure out how to drive it. My 1st thought is to use hex d type flip flops for the X and Y. The problem is that to get them scanning I'd have to one shot the reset line as well as connect the output of the last stage to the input of the first stage once it is scanning. Any thoughts would be appreciated.

Is this a practical project?, or a school one that forces you to use ancient technology?.

Assuming it's a practical project, it would be a LOT easier to use a PIC to do it, and my tutorials show how to run an 8x8 LED matrix from a single 18 pin PIC.

 

[alfa88]

Ouch! That hurts you young whipper snapper. Later I'll do an 8X8 with a PIC but for now I'm just playing with some cheap parts I got off of EBay. Here is the schematic and my scheme for the X,Y switches . I tried using a Microchip MCP120 for the power-on reset but it just seemed to overheat and not do as anticipated. After some time Microchip provided further documentation and even a free sample. As soon as I regroup I'll revise this post.

 

[3v0]

I am an old duffer and Nigel is still right.