7SegLED-4 with common anode

ksor · Post by **ksor** » Thu Oct 26, 2006 10:35 pm

I want to design with a unit with common CATHODE - how ?

Best regards

jimhumphries · Post by **jimhumphries** » Thu Oct 26, 2006 11:16 pm

Ksor:

The quick and dirty way is to ground the cathode and to put series resistors between the anodes and the PIC output port lines. For 5 milliamps per segment, use 700 Ohm resistors (650 Ohms is close enough). When the output port goes high (to +5V) current will flow through the segment and it will light up. The PIC output ports can source 25 mills each so they can easily handle this.

Jim

ksor · Post by **ksor** » Fri Oct 27, 2006 5:49 am

Yes yes - but how in FlodCode ?

And the common ANODE in the excisting 7SegLED HAS to be connected to a PORT - that's waste of ports - I believe.

I only have tried the DEMO version of the FlowCode.

KS

Post by **Benj** » Fri Oct 27, 2006 9:40 am

To do a common Anode design i think youll have to create the flow chart yourself. The inbuilt hardware modules are designed to work with the Matrix Multimedia hardware which is all common cathode.

Common cathode is a more intuative way for the 7seg to be powered as a segment lights up when there is a 1 output to a pin. However common anode lights up on the presence of a 0 output to a pin.

The 7seg uses 2 ports because this is the only way to be able to light up more then one display with different numbers. By cycling through the displays fast enough you can light up all 4 7segs one at a time without a sign of flickering.