Register to reply

Need help in understand the Markers on electronic chips

by null void
Tags: chips, electronic, markers
Share this thread:
null void
#1
Jan9-14, 11:49 PM
P: 92


I am just wondering what is the markers telling us, like what has shown in the diagram, the CLR is telling us if we apply active-high state input to that port, the flip flop will be reset right? But there is some case where the Markers is labeled as CLR' (bar-CLR) and there is a bubble attached at the port it should be something like "NOT gate". So in this case how do i determine whether should i apply high or low state to reset my flip flop?

If CLR is labeled without bar, does it mean when the port receive high state, ff is reset;
and if CLR is labeled with bar, does it mean when the port receive low state, ff is reset?

Do the bubble determine anything?
Phys.Org News Partner Engineering news on Phys.org
Comfortable climate indoors with porous glass
Crash-testing rivets
Customized surface inspection
null void
#2
Jan10-14, 01:13 AM
P: 92


This is the type of flip flop i see in my note, if the CLR port is active-Low, so supplying high state into the port will get inverted by the bubble b4 the port then become low, so can i say the flip flop is reset in this configuration?


But my note keep using this kind of configuration to avoid the flip flop from getting reset...
berkeman
#3
Jan10-14, 11:16 AM
Mentor
berkeman's Avatar
P: 40,730
No, the bubble is a marker, not an active thing. The bubble indicates active low for inputs, so the CLR~ input clears the FF when it is driven low. And the bubble and > markings on the clock input indicate that the clock causes the data to propagate on the negative-going edge of the clock input.

null void
#4
Jan10-14, 04:38 PM
P: 92
Need help in understand the Markers on electronic chips

oh, is that mean there is no such things like a CLR~ without bubble marker?
berkeman
#5
Jan10-14, 04:44 PM
Mentor
berkeman's Avatar
P: 40,730
Quote Quote by null void View Post
oh, is that mean there is no such things like a CLR~ without bubble marker?
Correct. No bubble means you use the active high signal CLR. A bubble means that the active low signal CLR~ is used to clear the FF.
null void
#6
Jan10-14, 04:50 PM
P: 92
Ah I see, thank you very much :)
tfr000
#7
Jan10-14, 04:51 PM
tfr000's Avatar
P: 119
Take a look at this, which explains a little about why designers use certain symbols:
http://www.eetimes.com/document.asp?doc_id=1274541

This page also explains some of it about halfway down, under "DeMorgan's Theorem":
http://www.physics.mcmaster.ca/phys4...b/chapter5.htm

Also
http://hyperphysics.phy-astr.gsu.edu...c/gate.html#c2

and this slide show isn't bad
http://webdocs.cs.ualberta.ca/~amara...ams/sld011.htm

I couldn't find any pages that do a fantastic job of explaining this...


Register to reply

Related Discussions
A DIY Electronic Speed Control ? is that viable? Electrical Engineering 18
In binary can we have a value with deci centi mili or more lower valued prefix? Computers 14
Term ground mean in an ELECTRONIC circuit? General Physics 3
Artificial polymer muscles that contract with electronic/magnetic stimulation? Materials & Chemical Engineering 2
Sept 2008: $550 Billion Disappeared in 1-2 hrs in an Electronic Run on the Banks Current Events 11