Proteus 8 project: On 5x7 Matrix LED Display show numbers 0-9 (up and down), with 1Hz, Counter, Multiplexer and EPROM.

[Daniel44]

I tried, but I'm stuck. I think I need to connect a shift register to the 7 rows but don't know how.
Here's the file how it looks like as of now.
Also a screenshot.
Any help would be good.

 

[FvM]

Circuit doesn't seem to serve a useful purpose. Please describe what you want to achieve. What shall be shown on the matrix display?

 

[Daniel44]

I want to display numbers on the matrix: 0,1,2,3,4,5,6,7,8,9 and then backwards.
I didn't start the simulation, but the shapes weren't good.
Could the problem be at the shift register?
This is the Truth table for Numbers 0-9 with columns 1-5 and it's HEX values.
This is the code located in the EPROM.

 

[FvM]

To start with a simple point, you must be able to address 5 dot columns individually but you have only 4 driver outputs.

Next point, counting up and down requires 19 states, but 4 counter bits can address only 16 states.

 

[BradtheRad]

Build this a step at a time, starting with a single digit count up/down made from a few IC's and an old-fashioned 7-segment led. Schematics for that have been around a long time. Once you make that project work, introduce features as you wish, one at a time until you arrive at your planned design.

 

[betwixt]

I suggest you do it a different way:
1. 0 to 5 binary counter (000 to 101 then reset)
2. decode 3 bits to 5 to drive the LED columns -and- drive 3 address lines on the EPROM.
3. connect 7 data outputs from the EPROM to the LED rows.
4. select the digit you want with different EPROM address lines.

Basically, you use the binary counter to select the column at the same time as you release the row data corresponding to that column from the EPROM. The counter can be free running and you could use a Johnson counter providing 1 of 5 sequential bits to save decoding if you are careful with the EPROM data.

The selection of digit is then made by using other EPROM address lines to select which block of bits are appropriate for the font you want.

Brian.