Gayan Soyza
Active Member
I built a 10x7 led display project using PIC 16f84a.It is the extended version or the 5x7 display.
My 10x7 display has 10 columns & 7 rows.Circuit is running well.I added some runing messeeges & some designs in it.
My problem is
* when column scaning the brightness of the leds are good.
* when the row scaning the brightness of the leds going low.
* when the letters displaying continuously the brightness falls.
The PIC output pins can draw only 25mA current. Its not quit enough to drive more leds...
Anybody knows how to prevent this??? I hope to extend this circuit to 20-25 columns to display a whole word...
I have attached the connection of LED's
My 10x7 display has 10 columns & 7 rows.Circuit is running well.I added some runing messeeges & some designs in it.
My problem is
* when column scaning the brightness of the leds are good.
* when the row scaning the brightness of the leds going low.
* when the letters displaying continuously the brightness falls.
The PIC output pins can draw only 25mA current. Its not quit enough to drive more leds...
Anybody knows how to prevent this??? I hope to extend this circuit to 20-25 columns to display a whole word...
I have attached the connection of LED's