DOT-matrix display(LED matrix) points for a good design.

[leoren_tm]

led matrix display

hello to all!!!i have a problem please help me.
Im new to Dot-matrix, i only had a byte of knowlegde on 8x8 dot matrix, and now im planning to use a dual Dot-matrix..
im using 8051 microcontroller(at89c2051), and now my problem is designing a Dual-matrixdisplay..
please suggest me a good circuit configuration,that would be capable, if i extend my 8x8 or shall i say a multiple 8x8 dot-matrix. i encountered shift register....but i dont know yet its limitation. or a link for any good dual dot matrix.
regards..
im also thinking that the shiftong of my display, would be handle more on the harware part...but not much connection...its because, for my processor to be efficient(if a hardware can do a thing, let the harware)

 

[huzaifahm]

led matrix proteus

Visit https://www.sparkfun.com/datasheets/Components/FYM-20881ABxx.pdf for a datasheet. It is just one of many dual-color matrices available.

If you have driven a single color matrix. What you need to do first is drive 2 or three at once. You should use 74595 shift register to input data to columns and use 7445N to select rows using 1/8 scanning method.

Then for the dual color, scheme is the same except, in single color you had one 74595 for each matrix, now you will have two. 4094 is much better than 74595 for driving dual color matrices.

Let me know if you need further help.

 

[zuisti]

dot matrix display tutorial

Hi leoren_tm,
I don't know exactly what do you want (what means the "dual Dot-matrix") but I'm attached here my old projects about this thema. These are using at89c2051 and 6 or 8 pieces of 7*5 LED dot matrix modules. I think the 7*5 is enough but it's easy to modify the circuits and the programs to 8*8 matrix.
For this projects I'm used Proteus because it can be simulate the circuit, if you don't have it, the circuit screenshots are also included.
Study first the original PDF from ELEKTOR (included in the folder ORI in the zip), this was also my start point.

Hope this helps
zuisti

 

[leoren_tm]

led matrix design

Visit https://www.sparkfun.com/datasheets/Components/FYM-20881ABxx.pdf for a datasheet. It is just one of many dual-color matrices available.

If you have driven a single color matrix. What you need to do first is drive 2 or three at once. You should use 74595 shift register to input data to columns and use 7445N to select rows using 1/8 scanning method.

Then for the dual color, scheme is the same except, in single color you had one 74595 for each matrix, now you will have two. 4094 is much better than 74595 for driving dual color matrices.

Let me know if you need further help.

i already try it...can you suggest an IC, that would be lest components needed and low cost? my problem realy is finding and IC, other IC could do that, but with some resistor and darlington pairs...etc

Added after 2 minutes:

Hi leoren_tm,
I don't know exactly what do you want (what means the "dual Dot-matrix") but I'm attached here my old projects about this thema. These are using at89c2051 and 6 or 8 pieces of 7*5 LED dot matrix modules. I think the 7*5 is enough but it's easy to modify the circuits and the programs to 8*8 matrix.
For this projects I'm used Proteus because it can be simulate the circuit, if you don't have it, the circuit screenshots are also included.
Study first the original PDF from ELEKTOR (included in the folder ORI in the zip), this was also my start point.

Hope this helps
zuisti

dual Color( red and Green) about elektor...i already read that topic...thanks.
im not using proteus, but can i ask info on ISIS??

 

[huzaifahm]

dot matrix display design

using 74164 and ULN2003 for driving columns is the cheapest method available. You can also look for maxim led driver here **broken link removed**

 

[leoren_tm]

designing led matrix

i read about max6969...its a good IC, but it cost $1.6 or close...bad design..
but its needs components like resitor on each line right?

 

[huzaifahm]

zuisti

well resistors are always there

 

[leoren_tm]

point on led matrix

as you said about maxim...its a direct drive(without resistor)
but it cost..maybe somewhere there is one cheap/...

 

[zuisti]

max6969 avr code

Hi 'leoren_tm',

1. Thank you for the points :|

2. Sorry for my mistake about dual - dual color display

3. I'm attached now a zip contained datasheets of several driver ICs used by me.

For example try (also) this one: TCA62746 from Toshiba. This is a 16bit reg, the current value of the 16-output is configurable using one external resistor (!).
There are also cheaper type, this is a family...

Highly recommended to use a shift register with output latches only, for the proper (high enough) refresh rate.

At least at my mind ...
Cheers
zuisti

 

[leoren_tm]

belajar dot matrix display

lol....i didnt give you yet a point...thats was just a help point..anyway...ill try scan you notes..thankyou
may i ask...do you design led display?

Added after 33 minutes:

zuisti if you realy need the points..i can give you...

 

[zuisti]

led dot matrix circuit

Hi;

> do you design led display?
Yes, but only one-color, and only in Proteus (ISIS), using AVR and PIC uCs.
However, my friends have builded my projects yet (with my help), are working as well.

A'propos Proteus:
> im not using proteus, but can i ask info on ISIS?
Yes, of course (also in a PM). Anyway, Proteus from Labcenter is an electronic CAD program (http://www.labcenter.co.uk/index.cfm), ISIS is the schematic and simulation (also VHDL) part, ARES is its PCB part. It's great !!

> if you realy need the points..i can give you...
No, thanks :|

Cheers
zuisti

 

[leoren_tm]

basic stamp led matrix

i read about the datasheets..anyway im still trying to get the components...
does proteus support MCU programming?

 

[zuisti]

dot matrix display circuit

does proteus support MCU programming?

Yes, 8051, AVR, ARM, PIC10-12-14-16-24, Basic Stamp, also source level debugging (C, Basic, ass), embedded assemblers for sw developing, with real periferies: hc164 ... hc595 shift regs, 5*7 and 8*8 LED matrix displays, char and graphics LCD, keyboard, real rs232 and USB simulation too ....
Look at the homepage!

 

[leoren_tm]

basic stamp 5 by 7 dot matrix

realy? im using pr*tel...what does basic stamps mean??
if you design in proteus, you dont need to have a hexfile generator? or something like keil?

 

[zuisti]

basic stamp led et max7219

Hi;

> what does basic stamps mean??

**broken link removed**

See the attached picture, it's a screenshot of a simple Proteus Basic Stamp demo project (you can download a working Proteus demo from their homepage).

> if you design in proteus, you dont need to have a hexfile generator? or something like keil?

If you are programming in assembly, Proteus has assemblers for many uCs to make the proper hex files, and you can it assign ('download, burn') to the uC.
Anyway, you can use also a lot of C compilers like Keil.


and
http://www.labcenter.co.uk/products/compilers.cfm

 

[leoren_tm]

basic stamp dot matrix

ah.ok..
back to my project...how can i elimanate shadowing? im driving my collum with a shiftregister,with latch and my row with 7port and a transistor,,

 

[leoren_tm]

belajar display dot matrix

i just try some shift register...but now my problem is, brigthness control...do you know some IC to control the voltage by some input? or has a function on PWM?

 

[humber]

89c2051 led matrix driving

Shadowing is often caused by a slow multiplexer - the driving transistors do not switch fast enough to avoid overlap between the displays or segments. Generally, it will be that the driving transistor switches off too slowly, rather than on.
Check this with a scope, or try to minimise the base drive impedance.

 

[leoren_tm]

basic stamp 74ls164 circuits

"base drive impedance"
cayou explain it futher? i think shodowing could be elimated by blanking...by means of your sofware..

 

[zuisti]

how to connect sms in the dot matrix circuitry

"base drive impedance"
cayou explain it futher? i think shodowing could be elimated by blanking...by means of your sofware..

Hi;
I agree with you, leoren_tm. The shadowing is caused (almost always) by the software timings. The advantage of multiplexing is also a disadvantage in this case. But ... do not use blanking, it may be cause more flickering. Use delay routines before any scroll and/or a little slower scrolling speed instead!

The "minimising of the base drive impedance of the row driver transistors" is also important, but far not so considerable for eliminate the shadowing. The delay caused by the saturation 'symptom' is far shorter as the program execution timings, at least at my mind.
Take care!
zuisti