No, as I'm more interested in the signal levels and edges than the actual logic-data. Besides, I want to be able to analyse signals to dertermine their nature and frequency. The logic-analyser would garble this too much. KreAture ----- Original Message ----- From: To: Sent: Tuesday, May 20, 2003 8:55 AM Subject: [EE]: Building a PC-based oscilloscope... or analyzer > if the scope has to be used for digital debugging... > ...wouldn't it be better to build a logic analyzer instead, with, let's > say 16 inputs, detecting anything below 1v as '0' and above 1v as '1' ? > (would fit so for 5v, 3v3, 2v5 and 1v8 logic, as well as for serial i/f > with +/-12v) > this could by clocked by an internal, variable clock source, or by an > external (up) clock (rising/falling/both edges). > as only logic states would have to be transferred, communication with the > pc would be much faster than for transferring analog levels. > when writing some kind of 'intelligent' software on the pc, this thing > could also do protocol analyzing. > tino > > > > > > > Kyrre Aalerud > Gesendet von: pic microcontroller discussion list > 19.05.03 21:52 > Bitte antworten an pic microcontroller discussion list > > > An: PICLIST@MITVMA.MIT.EDU > Kopie: > Thema: Re: [EE]: Building a PC-based oscilloscope... > > > From: "Bob Blick" > > Kyrre Aalerud said: > > > Problem is transferring to PC takes time, so unless I did this in > USB2.0 > > > I'd have to capture, then send all data and wait for trigger again. > > Are you also considering what it takes to display this data realtime? > Are > > you an experienced DirectX programmer? > > Otherwise you'll be stuck with a fancy "datalogger". > > > I will be using LabView to receive and display/log/zoom the data. > As long as one has some power in the computer this won't be any problem. > The data transfer on the other hand will take sooooooo much longer than > the > capture anyway, so realtime is out of the question. I may add USB2.0 > later > but for now I'll use paralell (i think). > > > Input preamps are another thing you need to be pretty experienced at in > > order to build something decent. > > I know. I will do it very simple. I will use i2c controllable resistors, > (Yes they exist!), to let PC adjust input amplification/dampening. The > final amp will be responsible for clipping the input so that teh ADC won't > go bonkers on me. (It only withstands minor errors like -0.1 volt below > gnd > and +1 or 2 volts above vcc.) I will be using amps that are spec'ed far > beyond 80 MHz in order to not disturb the signal too much... However, I > don't mind a little harmonic distortion and other wierdness as this will > be > a oscilloscope to debug digital circuitry. That way, as long as I have a > accurate clock I will be able to see or verify timing-issues and > sneak-a-peak at other data-traffic. > I will also get a good indication of the signal-levels. No need to have > them within the microvolt. > > > I realize I sound like a wet blanket, but there's a reason why > > oscilloscopes are priced the way they are. It costs money to make a good > > one. > > Not at all. Theese are important issues. As long as I know what I need I > think I'll be fine. > I do have some experience with mixed logic layout. Both in PCB size and > in > integrated design. > -- PCB is a cinch compared to integrated though :-) > > > At the very least, you should buy a used analog oscilloscope and use the > > frontend and trigger sections. Then you only have the digital and > software > > challenges. > > > Cheerful regards, > > Bob > > Every adjustment will be in software... Fancy looking! > The scope hardware will be a black box with a good connector :-) > > KreAture > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- > http://www.piclist.com#nomail Going offline? Don't AutoReply us! > email listserv@mitvma.mit.edu with SET PICList DIGEST in the body > -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body