I would like to connect multiple 7 Segment display to the arduino ....
As the arduino duemilanove does not have much Digital outputs I would like to connect multiple & segment displays in parallel but coltroll them with the common pin...
Make all the 7 segment display glow individually at a vrey high rate and displaying the multiple digit numbers...
Like in this circuit below...
would like to connect multiple
Define "multiple".
You could use shift registers.
The right-hand side of that circuit is a standard multiplexing setup. You could drive that in any one of a dozen ways.
OK so that's only 3, but there are others and variations of the above.
What are you trying to achieve? How bright do the LEDs have to be?
Rob
Look at the MAX7219 - it can control up to 8 individual digits (inc. DP) and you can daisy chain them. Very easy to use, works on SPI. Controllable brightness as well.
You can pick up several very cheaply from eBay.
Here's a link to the datasheet.
The arduino can multiplex as shown, driving 20mA to the parallel segments, and pulling the common cathode low on the active device.
Several folks here recently have done just that.
Only drawback is that it uses 11 pins.
MAX7219/7221 will letyou control up to displays, handles all the multiplexing, updating is as simple as writing a value to 1 of 8 registers.
Only ties up the SPI lines (D11, D12, D13) and whatever you use as the SlaveSelect line (normally D10, but you can use whatever you'd like).
