dot matrix board

[prosound90]

hi

i need your opinion for designing an 5x7 or 5x8 or 8x8 dot matrix led sign

i'am going to use a PIC as a MCU and it will have a tempreture display

+ time/date and a messege's with an extra set of font.

what will be the eazy way to iterface the dot matrix to the PIC for simple

addressing and power handling with the consederation of useing 2 ROWs

please give advice on chips to use i'am thinking of the 74hc595 on the columns and ULN2003 or 2803 on the rows.

thanks

 

[prosound90]

Come on guys help me out....................any idea's.

 

[panic mode]

Well what do you really plan on doing?

If you are making large displays 5x7 clusters can help reduce
wiring. The idea is is to create matrix (rows and columns) and
refresh frequently (faster than eye can react).

Since the most clusters are only 5x7 LED high, think about arrangement
and scanning to get higher duty cycle for all LEDs. It means that
if you go with say ten 5x7 clusters you would get display 7x50 (HxW).
Although it is simpler to scan columns (each column as one byte),
it would be better to do it in rows so the duty cycle of LED which is on
would be some 14% instead of max 2%.

The lower duty, less brightness from the LEDs. Sure you can use
higher drive current (well you would probably do it either way),
but it is safer to keep it down - LEDs are moe likely to live longer
and if your PIC gets stuck (program error or whatever).

If you are not interested in that big displays, consider using
character or graphic displays. With background lighting and
good selection of colors they can be very atractive.
This would also mean much simpler interface (fewer I/O pins)
and lot's of code samples to choose from (you don't want to
reinvent the wheel, do you?).

 

[prosound90]

hi

iam intresting in making an outdoor display that can handel 2 or 3 line of

scrolling text with small size font and can be combined to display large font according to software,

can be one color or 2 ,

i think most commercial displays made out of cluster of diffrent size's of

5x7.

the big Q is witch disply driver's to use and in what interface???

iam asuming the speed is very important in thease applcations

because of the refreshing rate

 

[naljta]

take a look at max6955 or max7219 by www.maxim-ic.com