5x7 dot matrix LED using P89v51rd2

[sidatsaace]

p89v51rd2

hi to all,
im interfacing a dotmatrix led with 89v51rd2 controller using 2 latches(74hc573).my connection details are:

PORT0-->74hc573--->uln2803--->pull up resistor1k--->to row of the matrix led
PORT1-->74hc573--->column of the matrix LED
PORT3.5,6,7-->3-8 decoder-->latch enable pins

i overcome with the prob:

if i have more than 3 leds to be glown in a column automatically the brightness gets dimmed(for eg: if i am glowing value 1, the brightness of LED in 3rd col gets lowered in as all the LEDs glow in it.

 

[embeddedlover]

kind of latch used in 5 by 7 led matrix

The main problem with these led circuits using latch is that there won't be proper intensity control
According to ur explanation i don't see a current limting resistors in ur circuit.....
sometimes the leds get damaged without it

In ur case i think the current ur sourcing is not enough.

The pull-up resistor u have added is very useful in eliminating any ghosting.
Try to use 51ohm in the same place.

 

[yellowboy_75]

dot matrix led

I just reached this page
**broken link removed**

Download the datasheet from this page, which has schematics for seven segment display.

YB

 

[sidatsaace]

multiplex led matrix 5x7

as the prob is lack of current is it advisable to use current limiting resistor there.......

 

[embeddedlover]

96 column led display row scanning

Any where series resistor is s must for led to restrict current.
As ur case is different, that is why try 2 use lower vale of resistor for pull up.

 

[sidatsaace]

5x7-dot-matrix-led

k lemme try that thnx... but wen i press the reset button of the controller all the LEDs glow with perfect intensity and it makes me to doubt whether is there any prob with my code....even though if the code s wrong why come the other columns glow correctly......

 

[Tajinder Singh]

74hc573 dotmatrix

its obvious that leds in a column will dim when all leds in that column will glow.
Reason:
your circuit is not good. your single output of 74573 is sourcing current to all leds in that column. so its total current reqd. is 20ma x 7. and 74573 is limiting current from this side.
on the other sides you have installed ULN on which you have load of only 1 led which just 20ma.

so either change your circuit or change the scanning seq. i.e. instead of multiplexing columns , multiplex rows.

and when you press your reset key, the controller don't do multiplexing so all leds glow with full intensity. as intensity itself lowers at the time of multiplexing.


so you need to change either of it software or hardware.

 

[sidatsaace]

74573 and seven segments

oh thnx...but still im not using decoder for only column im just using it to switch it b/w the row and column latches.....

 

[narindia16]

p89v51rd2 5x7 matrix led project

Hello Friends,

I read all ur discussion. i am new in digital circuits. I have knowlage of digital circuits and have some programming knowlage too but don't dont' have real world experiance. I have a working led matrix matrix of 7 rows and 96 rows. I want to test it with my won microcontroller.

I am going to use this with my p89v51 microcontroller. but please somebody help me with the program of it. as i never worked on such program before. and please also guide me the procedure of programming the new microcontroller. I have purchased a IC programmer for the same supporting FlashMagic.

I need help urgently. Please send the source code of the same to my mail id narinderATnarinderpalDOTcom

Regards,
Narinder

 

[nandhu015]

5x7 dot matrix led

Hello Friends,

I read all ur discussion. i am new in digital circuits. I have knowlage of digital circuits and have some programming knowlage too but don't dont' have real world experiance. I have a working led matrix matrix of 7 rows and 96 rows. I want to test it with my won microcontroller.

I am going to use this with my p89v51 microcontroller. but please somebody help me with the program of it. as i never worked on such program before. and please also guide me the procedure of programming the new microcontroller. I have purchased a IC programmer for the same supporting FlashMagic.

I need help urgently. Please send the source code of the same to my mail id narinderATnarinderpalDOTcom

Regards,
Narinder

Hai
Welcome to the world of microcontrollers

As new to microcontrollers, start some thing simple. Read tutorials about programming microcontrollers. Try some simple circuits (blinking led) and then go for a project.

Best of Luck

Nandhu

 

[narindia16]

source code for p89v51rd2

Thanks a lot for your valuable advice but i badly need to make that work with my own microcontroller. I don't have time to do experiments. and more importently i have ready circuit with me and have knowlage of C then why not try this as a first thing..............

So please help me out.....

 

[narindia16]

led matrix current resistors

Please Somebody Help me ........i need it urgently

 

[sidatsaace]

uln matriz led 5x7

hi
just gimme a brief expln about ur matrix led
(i.e., rows and columns)

 

[narindia16]

5x7 dot

I have two kits ready with me.

1. 7 rows and 96 colums

2. 16 rows and 96 coulums.

i want to program microcontroller for the both to make it work in my own way.

Please help me out

 

[narindia16]

led matrix latching

Hey guys do something pleaseeeeeeee......

 

[sidatsaace]

5 by 7 dot matrix

i have built a on module of 5x7 matrix LED whereas i had anode collection as row and cathode arrays as column i had had connected latches 573 to both column and row and a uln at column side the module is perfect...the prob is i doubt whether it ll creates any prob in case of brightness as it takes a delay for scanning through all the 30 columns

Added after 1 minutes:

in case if i add 5 more modules with it

 

[mad8]

can ny1 plz post the circuit and code for 5*7 led matrix...plz its urgent