Dot matrix led display

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Vonn

Joined: 06 Oct 2002
Posts: 254
Helped: 2

11 Dec 2002 10:32 Dot matrix led display

Hi all
i am building an dot matrix led display board i think to make it interfaced with pc to enter the text through it ... if you have any idea or suggestion plz let me know Rolling Eyes

penrico

Joined: 28 Aug 2001
Posts: 222
Helped: 8
Location: Argentina

11 Dec 2002 15:32

Specify more about what resolution you have, or how many characters you will display, etc.

I think easys way to do it, is using 5x8 led dot array, you must put 16 together, and control it with a few logic and a microcontroler like PIC, to control and comunicate it with a PC using serial port.

eYe

Joined: 12 Aug 2001
Posts: 104
Helped: 1

12 Dec 2002 1:22

check Dallas/Maxim.
There is a chip from LED Dot Matrix Controller.
You will get easy in programmning

braveh4rt

Joined: 13 Dec 2002
Posts: 11
Location: Indonesia

13 Dec 2002 5:56

why not to use ATMEL Controller....

to interfaced with pc use maxim 232 chip and the atmel chip is atc89c52

algilsan

Joined: 20 Jan 2002
Posts: 120
Helped: 1

14 Dec 2002 11:44

i have worked in led based pannels factory, so ask everything you want, but be a bit detailed.

regards

year

Joined: 21 Feb 2002
Posts: 99

14 Dec 2002 12:36

You may know as follows

- Constant Current Control for obtaining good brightness

- Dynamic Drive or Static Drive to make suitable system

- Understanding of FONT structure

Vonn

Joined: 06 Oct 2002
Posts: 254
Helped: 2

14 Dec 2002 14:45

i want to display a line of 10 characters with resolution 5 x 8 . with refresh " raster " tech. (dynamic driver)

year

Joined: 21 Feb 2002
Posts: 99

14 Dec 2002 17:03

You have to consider where it is used !!!
Dynamic drive can not give you Brightness or Luminance.
It is real poblem in field with dynamic drive. Out-door is very dangeous for this reason.
In detail, This system will be 50digit * 8bit. As a result, brightness is 1/50
Circuit is very simple 50 digit is consist of shit register or F/F 8 bit is direct I/O port or latch with array TR.
Software side, interupt routine refresh one digit. Main loop will access(write) display buffer(50 bytes).

fatkiller

Joined: 25 Sep 2002
Posts: 17

15 Dec 2002 2:52

Hi,

I join 3 Exemples form ELEKTOR revue (french & English).

The X02-2000.prf = With COP8782 MCU: 2 Modules:
1) Keyboard (PS2) directly connected and sending (in IR) to display module.
2) Display module wthit 7 dot led (5*7) dsplay.

The X03-2000.pdf its exemple with 7 segment display

The X06-2001.pdf with 89C4051 mcu and 6 dot led (5*7) display connected to rs232, it's possibe to chain multiple module (max 15). I have tested this, wotks correctely just a small problem of refresh rate with the upper caracter.

Bye
Fatkiller
The next file on another post, sorry max 4 by post.
Ps: F=French E= English

fatkiller

Joined: 25 Sep 2002
Posts: 17

15 Dec 2002 2:54

Last Files

algilsan

Joined: 20 Jan 2002
Posts: 120
Helped: 1

15 Dec 2002 17:42

Hello,

i have to make a you a question, if you tend to mux 50 bytes per second, like Year said, you probably not be able to view characters with an useful brightness. I should make this thing ,instead:

Make an static driver for one character map, i mean 5 bytes, so i recomend you to use a shit register with latched buffered outputs to drive a single led. The common annode or cathode of this character map will be pass trouwgh a power transistor. Ok! this register will come with CLK, STROBE and BLANK signal. Then BLANK signal is to make brightness control. There are IC in MICREL, MAXIM, with this characteristics, i think they were TPIC or MPIC.

Well once you have this done, you have to join all single Character leds to this outputs. then you will have 10 transistors. So you will have three control signals to control bytes and then control signals to decide what character to display. to make this more easy you can use a shift register for these 10 signals so you only need now two sgnals CLK1 and STROBE1. and that's all, now you mux time are reduced to 1/10 instead 1/50.

regards

algilsan

Joined: 20 Jan 2002
Posts: 120
Helped: 1

15 Dec 2002 17:46

Sorry for my english. i have to explain something i now in my not native idiom, and it's not very ease for me.

Sorry again

pcduong

Joined: 03 Dec 2002
Posts: 14
Location: Hanoi, Vietnam

20 Dec 2002 19:32

Hi,
For matrix led display there is a excelent drivers from MAXIM :
MAX7219 or MAX7221.
They use a simple SPI interface to control the led matrix and may be cascaded.
OR you can use the shift register 74HC595 which contains in it self a tristate latch and may be controled using SPI protocol.

techie

Joined: 05 Feb 2002
Posts: 833
Helped: 42

20 Dec 2002 19:41

Which constant current drive IC is best suited for LED displays? specially for the matrix LED screens used for outdoor applications.

bobcat1

Joined: 10 Jul 2002
Posts: 833
Helped: 31

20 Dec 2002 23:03 use 6276 from alegro

use 6276 from alegro it's 16 bit led driver shift register and it's low cost
$ 1.1 in 1000 qty

if u need singles qty go to nuhorizons.com but it's cost bit higher

bobi

pcduong

Joined: 03 Dec 2002
Posts: 14
Location: Hanoi, Vietnam

11 Mar 2003 18:37

Hi Techie
Have a look at
http://www.mblock.com.tw/pro/16-bit.html
There are low cost constant current drivers IC for LED matrix display.
Regards.

techie

Joined: 05 Feb 2002
Posts: 833
Helped: 42

11 Mar 2003 18:56

How much does this Chip cost in quantity of 1000 pcs or sso

Gomez

Joined: 12 Feb 2002
Posts: 107
Helped: 4

11 Mar 2003 21:12

techie wrote:

How much does this Chip cost in quantity of 1000 pcs or sso

I have take the MBI5016CP for my application. The price is 0,68USD/1pcs (1700pcs). The MBI5016 is in SSOP. Allegro has't SSOP device.

Shipping is with FedEx and T/T in advance. Whenn you need any support, call
Vivian Chang
Office phone no.:+886-3-5790068~708
vivian(at)mblock.com.tw

Gomez

Gomez

Joined: 12 Feb 2002
Posts: 107
Helped: 4

11 Mar 2003 21:17

braveh4rt wrote:

why not to use ATMEL Controller....

to interfaced with pc use maxim 232 chip and the atmel chip is atc89c52

For constant current drivers IC for LED you need a controller with SPI. The at89c52 has't SPI.

Gomez

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