View Full Version : The PDB and LED display

05-21-2005, 12:19 AM
I just received my PDB - what an awesome piece of work it is - everything on it but a microwave.

I decided my first effort would be to turn on the 5-digit LED - couldn't wait to see the blue digits.· I used two daisy-chained 595s.· The first one takes the selected segments high, and the second one takes the selected digit low.· I was concerned that sinking a digit might stress the 595, but I let it run for quite awhile and it stayed cool.· The 595 is spec'd at 70ma max through Vss or Vdd, and even with all 7 segments lit, I doubt that any digit would exceed 70ma so I guess that part is OK.

The sample code displays the digits 1-2-3-4-5 and uses 1 byte of RAM.
The display uses only 3 Stamp I/O lines to drive all 5 digits, and the parts cost is $1.06.

The second byte in each shiftout can be replaced by any·BYTE variable, which with a little code-writing will let you display time, temperature, or what have you.

Have fun :))

Sid Weaver
Need a bezel for your LCD?

Newzed@aol.com (mailto:Newzed@aol.com)