Help with led driver

[iceisfun]

I have some 7 segment common anode 12 vdc LED segments I am trying to drive with a Max7219 and a PIC32 and I'm having trouble with the way these 7 segment displays work.

I've got some common cathode normal 7 segment displays that I have working great in my example breadboard.

Can someone give me some direction on driving these monsters?

[mariush]

Max 7219 is a common cathode driver ... it's kinda hard and pointless to use it with common anode led segments.

You can use something like ULN2003A (7 darlington array) or ULN2803A (8 darlington array) which enables you to light up individual segments... like in this picture here:



 You enable power to a particular number in the seven segment display by energizing the npn transistor npn transistor (or whatever you want, mosfet etc), then light up the segments you want by sending power to the base of individual darlington elements in the uln2803a set. When the darlington element is active, it passes electricity to ground, so it completes the circuit making electricity flow through the led segments. If you want to reduce the number of pins, you can add a simple shift register IC in the front of the uln2803A.

[iceisfun]

Ok I have this working now, thanks

I've used these to drive DPSS TTL laser to ground before, should have thought of these

[geraldjhg]

hi
not easy with current hog displays
for newer displays (less thn 5ma per seg)
drive directly from mcu and use a uln 2003
as digit sink
saludos

[iceisfun]

I got it working with the MAX7219, ULN2803 and a Hex Inverter