multiplexing techniques with two 74HC595

[atoo]

someone could help me

still do not know how to send a byte
with two 74HC595 in a 8x8 matrix

74HC595 row and 74hc595 column

[temtronic]

Controlling the 8by8 matrix LED can be broken down into simpler parts. A 'row' driver(595) and a 'column' driver(595). For any LED to be on the 'row' must be high( '1') and the column' must be low( '0').

Start with one 595 and connect 8 LEDs(and resistors) in common cathode configuration.
Using the CCS supplied example,cut code to turn on the LEDS in various patterns.

WHEN that works fine then

Use the other 595 and connect 8 LEDs(and resistors) in common ANODE configuration
Using the CCS supplied example,cut code to turn on the LEDS in various patterns.be SURE to EDIT the code as now what was 'on' is now 'off'.

It really helps to use graph paper to 'see' the bit patterns and logic necessary to control the LEDs.
The 'trick' or 'key' is to start small,build upon knwoledge you gain by observing what works(and doesn't).As for the 'bit' patterns to make characters, again graph paper is very,very helpful is determining the 'mask'(actual data to 595) needed to display whatever you want.
For resistors, I'd use 8 - 100r in series with the anodes(rows) AND 8 - 100r in series with the cathodes(columns).This ensures there's always a current limit though 8 - 200r in either row or col would work as well.


hth
jay


You can simply the project if your PIC has 2 8 bit ports available. This eliminates the 595s.

[Mike Walne]

Giv us some idea of:-

1) Your schematic.
2) Your code.

Is your circuit something like this?

[atoo]

I would make some code to delete the byte using output toggling. Can Be?

Or any other technique an array of bitwise be cool?

Or rather, would only be possible with some simple matrix and FOR loops?

Suggest what kind of suggestion ?


something without bookstore 74HC595

independente

Atoo
Charles PB

[Ttelmah]

It depends totally on how your code needs to be designed.
One approach would be to have a timer tick, and then have this on every 'tick' output the next pattern on the column, and every eight ticks change rows, doing nothing else.
Your main code can then just specify what needs to be output, and the tick will keep on doing this at the designed rate, so ensuring the display keeps operating whatever else is going on.
The key point is that you need to get the control of the chips working _first_, and then work out the timings you need, and work out how to provide these.

Best Wishes

[Mike Walne]

[asmboy]

in the era of ubiquitous, and cheap LCD character displays -
is there a reason you must use multiplexed LEDS?

in my case it only took ONE experience with using a mux'd display in
a small ( supposed to be ) very high audio quality FM transmitter exciter design, to learn my lesson. the mux switching process was costing almost
6 db of nasty noise floor trash in the recovered audio, unless a lot of extra $$ were to be dumped into extra power supply cleaning.

An LCD with blue-led backlit display made the design cheaper, and very well accepted by the customer to boot.

do you HAVE to have an LED matrix ??

[atoo]

[temtronic]

Please, use the CCS supplied '595 driver code that's in the 'examples' folder.You'll get better support and your project working faster if you do.
The code you show is too 'messy' to follow but I 'think' it's trying to control the 595 using the matrix data.I'm NOT about to waste any more time on it, the CCS example code does work!
Also you do not tell us the pin assignments ,that's very very important and should be in the first 10-15 lines of code.

hth
jay

[atoo]

this right
eu entendo

I'll try

[Mike Walne]

You're making it difficult to help you.

You've editted a post after getting a response, that makes it impossible to follow the thread.

Please:-

1) Show us your circuit. We need to know which way round your display is connected.
2) As suggested, use the CCS example to start with. The CCS code is known to work, will prove your circuit operates, and you will get a feel for how to drive the display.
3) Keep your code simple and show us complete compilable code when you get stuck.

Mike

[atoo]

Mike Walne


Thank you for listening
Has Helped me a lot from start to finish

I managed to complete without the used library conssegui six-pin
I discovered there are many possibilities to do this
problem solved! looks like the design of the array you posted!
Thank resolved


with the drawing above you complete with loops