Mike Keitz wrote: > > On Thu, 30 Apr 1998 07:37:17 -0700 Andre Abelian > writes: > >Hi to all engineers. > > > >I am working on project based on multiplex display, keypad, and DAC. > >Every thing is fine except one thing. I want to add blinking led like > >when you hit > >enter the led will blink plus it will display what you want. right now > >when I hit > >enter led will turn on in same loop when I add delay after led like > > Since you are already scanning the display at a constant rate, it is easy > to make some or all digits blink. Add a RAM counter that increments > every time you finish scanning the display (scan the last digit) and just > rolls over freely. When a certain bit in the counter is set (which one > to use depends on how rapid the blinking should be), blank off the digits > that should blink. Blanking them off means that when their time to scan > comes up, ignore the value that should be displayed and write all ones or > zeros for the segment data so the segements are all off. > > Using a bit in a binary counter means the display will blink on and off > at 50% duty. For example if the display scans at 50 Hz and you use bit 4 > of the counter, the blinking will be on for 320 ms and off for 320 ms. > If you use the LSB, which is incrementing very fast, you can get a "dim" > effect (blanked every other scan) which may be useful as well. Set up > other bits in RAM to indicate which digits should blink. If you just > want the whole display to blink like a clock that has not been set, then > only one bit is required. The main program would set or clear the > blinking flags as needed. The display will start and stop blinking "in > the background". > > If you're talking about discrete LEDs, you can also control and time the > blinking of them with the display multiplexing routine. They can have > their own port pins or be connected in the multiplexed array (7 or 8 > discrete LEDs connected like the segments in another digit). > > _____________________________________________________________________ > You don't need to buy Internet access to use free Internet e-mail. > Get completely free e-mail from Juno at http://www.juno.com > Or call Juno at (800) 654-JUNO [654-5866] Write a book and become famous ! (well to embedded programmers anyway) excelent clarity Mike ! regards, graham.daniel@xtra.co.nz -- I invent therefore I am.