Digital Timing - Page 1
Forum section: electronics / beginners

author: Shenandoah
author_rank: Regular Contributor
timestamp: July 26, 2013, 09:30:37 pm
content: Hi all,I'm now studying digital design...and one thing I cannot comprehend how timing works in digital circuits. For instance how can I tell a specific part of the system that's it's okay to put its output on a bus so that the other part can process it, and then tell the another part that it's ready to read that output?Thanks.

author: dfmischler
author_rank: Frequent Contributor
timestamp: July 26, 2013, 10:36:10 pm
content: Quote from: Shenandoah on July 26, 2013, 09:30:37 pmThere are several different ways to do that. Most simple systems are synchronous. Do you have a particular family of parts in mind? If so, we can probably come up with the appropriate details. Otherwise, check outthis for Z80(TIMING starts on page 11). There are both simpler and more complex ways to get this done.

author: madires
author_rank: Super Contributor
timestamp: July 26, 2013, 10:37:38 pm
content: Quote from: Shenandoah on July 26, 2013, 09:30:37 pmMost logic/digital ICs got control pins to deal with that problem. For example the IC putting data on the bus might have a "output enable" trigger pin and the receiver a "take input" pin. To time both ICs correctly you could use a MCU controling both ICs or you would put some logic in between to trigger the outputting IC and delay the "take input" signal (with an even number of inverters or whatever you got) to give the outputting IC enough time. Or you use a system clock and some logic to drive all ICs in a specific sequence timed by the clock. The important thing to know is that all ICs need some time to do their job and the datasheet gives you the timing details. For more complex systems the bus will have several control/handshake lines to control communication. LCD modules are a good example.

author: free_electron
author_rank: Super Contributor
timestamp: July 26, 2013, 10:55:56 pm
content: Quote from: Shenandoah on July 26, 2013, 09:30:37 pmYou need to build a waferfab first and design chips. Then it will all become clear...

author: M. András
author_rank: Super Contributor
timestamp: July 27, 2013, 10:04:31 am
content: Quote from: free_electron on July 26, 2013, 10:55:56 pmsimple sentences reveal the true knowledge of the self promoted young genius right?:D:D

author: madires
author_rank: Super Contributor
timestamp: July 27, 2013, 01:15:32 pm
content: Quote from: M. András on July 27, 2013, 10:04:31 amI don't know if he meant it in a figurative sense, but there is one ;-) All the prodution processes in the waferfab need to be timed and run in a specific sequence.

author: M. András
author_rank: Super Contributor
timestamp: July 27, 2013, 01:35:30 pm
content: Quote from: madires on July 27, 2013, 01:15:32 pmyes its meant to be figurative. seriously the guy wanted to open a waferfab and he ask these sort of questions.

author: 4to20Milliamps
author_rank: Regular Contributor
timestamp: July 27, 2013, 02:36:50 pm
content: It sounds like you just need a better tool to visualize the process flow, this may not be the answer you are looking for but I would sit down and get a good idea of what you want your circuit to do then do a step by step analysis of how to go about doing it.http://www.technologystudent.com/despro_flsh/progm1.htmlI'm sure there are free tools out there but I found this as an example:http://www.assemblyflowchart.com/

author: Shenandoah
author_rank: Regular Contributor
timestamp: July 28, 2013, 04:43:53 pm
content: Quote from: free_electron on July 26, 2013, 10:55:56 pmYou loser...why r u afraid of other people knowledge??? A typical loser, probably old fart loser.

author: M. András
author_rank: Super Contributor
timestamp: July 28, 2013, 05:08:30 pm
content: yeah but the man you call a loser works at a semiconductor company and published enough work to earn a credit and represent his knowledge, while you are posting dreams without foothold

author: free_electron
author_rank: Super Contributor
timestamp: July 28, 2013, 06:07:13 pm
content: Quote from: Shenandoah on July 28, 2013, 04:43:53 pmi think you suffer from bipolar disorder ... maybe they didn't bake you long enough in the oven after implant...(That's a semiconductor process engineer joke, you may not understand)

author: SeanB
author_rank: Super Contributor
timestamp: July 28, 2013, 06:30:30 pm
content: More like they forgot the mask layer on his ASIC............... Just a sea of uncommitted gates now and no way to fix it.

author: c4757p
author_rank: Super Contributor
timestamp: July 28, 2013, 06:33:24 pm
content: "Sea of uncommitted gates" and "missing the mask layer on your ASIC" are my new favorite insults.

author: SeanB
author_rank: Super Contributor
timestamp: July 28, 2013, 09:05:11 pm
content: You are welcome, sometimes I amaze even myself.

author: free_electron
author_rank: Super Contributor
timestamp: July 28, 2013, 09:41:56 pm
content: he's missing a few masks in his stack ...