View Full Version : Pulsout and TTL F/Fs

Buck Rogers
01-29-2006, 02:33 PM
Here's a new one on me. I know that the Pulsout command can be used to clock a shift register, as for the speech synthesizer example that Jon W. discussed with us on the old Yahoo forum, and I believe here in this forum as well, but that's not what I'm using it for.
During my normal processes of obtaining stock I would buy surplus collections of TTL logic. The majority of these are Series 74, and Series 74LS, but some are Series 74H, and even a few Series 74S, and one or two Series 74L parts. Some of these are this part number SN74H72. For those of you who do not have immediate access to a TI databook, particularly one from the late '70s to early '80s, and even the last physical one published from 1987 or 1986, (For those of you who know who my handle is, that is the year he's supposed to have started his 500 year snooze.) this part is an And Gated J/K F/F with the Preset and Clear functions brought out. Each and gate has three inputs.
I took the basic program (And that is a pun!) and loaded it. That after connecting the part in place of the LED. It worked. The F/F toggles. I then modified it accordingly:

By changing the numbers in the pause and the pulsout I was able to·change the delay, I think I·changed it to about 100Ms instead of 1Sec and the pulses are being sent at 250Ms, instead of 25. To be honest I·was convinced that it would not work. This tells me that I could easily connect a shift register like the SN74HC594 to the Px points on the stamp and have it clocked that same way. Now shifting data into the register is a problem I'll adress later in this thread.http://forums.parallax.com/images/smilies/yeah.gif

And I believe I am on a roll. http://forums.parallax.com/images/smilies/roll.gif

' This program blinks an LED on for 25 ms at 1-second intervals. Connect an
' LED (active-low) to I/O pin 0.
' {$STAMP BS1}
' {$PBASIC 1.0}

HIGH 0 ' make P0 high (LED off)
PULSOUT 0, 25000 ' flash LED for 25 ms
PAUSE 100 ' one second delay

Buck Rogers

www.gregg.levine.name (http://www.gregg.levine.name)