Hey guys i know im a huge pain. I was going to use a ULN2803 for driving my LED Matrix but noticed i cant use it for the Column Driver without using another IC to invert it. I wanted to know if i can simply use a 4017 to drive each LED Column directly im using 270 OHM resistors and plan on using 5v supply... so thats a max of:
130mA per column but remember since it will never be a solid on its actually going to be less since its basically strobbing. The column is ANODE and the ROW are CATHODE.
Hey guys i know im a huge pain. I was going to use a ULN2803 for driving my LED Matrix but noticed i cant use it for the Column Driver without using another IC to invert it. I wanted to know if i can simply use a 4017 to drive each LED Column directly im using 270 OHM resistors and plan on using 5v supply... so thats a max of:
130mA per column but remember since it will never be a solid on its actually going to be less since its basically strobbing. The column is ANODE and the ROW are CATHODE.
i havent thats the thing.. heh i never fully plan anything heh... The LED Matrixs i have are 5x7 and have ANODE Columns and CATHODE Rows...
I plan on Using RB0:6 for ROWs 1-7 and using the 4017's for selecting the current column on.
So i assume you call that scanning columns?
I havent made anything official on the board im doing yet only that all the Rows are tied together from each matrix.
im planing on only using resistors on the 7 pins for the 2803... this way i save on resistors heh.. even tho i have a ton!! but this ensures each LED has the same brightness also.
im planing on only using resistors on the 7 pins for the 2803... this way i save on resistors heh.. even tho i have a ton!! but this ensures each LED has the same brightness also.
sorry..
in my work i usually view the list text file.
transistor can use pnp or npn, if PNP like picture, data to send to make led on is low and visa versa.
IC5-IC7 decode counter 4017.
IC8 is AND gate like 7408 or varian
IC4 is pic16f877
i build led array because in my town difficult buy matrixes
R for row driver depend at rating led and power apply to transistor.
if we use Vs 5 volt and current led 30 Ma R is 100 ohm.
my bad. on IC2 CD+ not connected like IC1 and IC3.
IC1,IC2,IC3 = ULN2803.
IC8 AND gate. like 7408 or 74ls08, 74hc08 etc.
i posting my code in
**broken link removed**
it working and i still deploving my code for communication with PC.
you can tri this code and schematic in proteus. in proteus you can change led with matrix array but
must change ULN 2803 with hex inverter or NOT gate, i don't understan why led matrix not working with ULN2803 in proteus.
and if you use PNP transistor like my schematic you must invert data table otherwise your display will inverted.
or if you not change code you can change transistor to NPN.