Help me with coding 8255 for lighting up numbers using 8x8 LEDs

[b-shoitan]

how can i design a ckt using 8255 to light up numbers using 8x8 leds ?? tips on ckt design, coding pls

 

[vibeeshpv]

Re: 8255 prob

how u going to inter face the 8255? r u using microcontroller or some counter?

 

[mondunno]

8255 prob

8255 has 3 ports, which r more than enough

just make a hardware which can switch "on" any led out of 8x8 matrix(thats easy)
now switch on the required led for about 4milli seconds.
the leds required to glow are light for about 4milliseconds(one by one), REMEMBER: only one LED must be switched on at once

due to the perception of human vision, it looks like all the leds are glowing at once

all the best, acknowledge when ur project is working

 

[nandhu015]

Re: 8255 prob

Hai

Take care of timings


My suggestion is use some serial to parrallel convertor instead of 8255
It saves microcontroller pins.

Nandhu

 

[b-shoitan]

Re: 8255 prob

how u going to inter face the 8255? r u using microcontroller or some counter?

donno

will use parallel port

Added after 2 minutes:

8255 has 3 ports, which r more than enough

just make a hardware which can switch "on" any led out of 8x8 matrix(thats easy)
now switch on the required led for about 4milli seconds.
the leds required to glow are light for about 4milliseconds(one by one), REMEMBER: only one LED must be switched on at once

due to the perception of human vision, it looks like all the leds are glowing at once

all the best, acknowledge when ur project is working

any help or links about the circuit ??

how to write a code?? (will interface using the pc parallel port)

thanks

-
ahsan

 

[daviddlc]

Re: 8255 prob

how can i design a ckt using 8255 to light up numbers using 8x8 leds ?? tips on ckt design, coding pls

How many numbers ?

With 3 ports of the 8255 the easiest way is to control up to 2 8x8 LED matrix.

If you want to control more than 3, then you will need additional circuits.