I'm trying to build a cable, and for any really helpful debugging, I need a decent 'scope, something that can cope with 19200 RS232 would be nice. I had a really nice LeCroy one at work that was colour, freeze trigger, printer etc, but it costs £15k so I can't really get one for home lol. Anyone have any particular recommendations? What I would find most useful is a way for the screen to freeze upon a trigger (single trigger), so that I can use it with signals that don't repeat frequently. I'm guessing what I want is a 'storage scope' (from the site below), but the price, the price! Are PC based ones any good? I'm a student, so can't afford that much I found this site ages ago, anyone recommend anything that looks good off it?
Im in a similar situation, id really like a DSO (digital storage 'scope) but even on ebay theyre silly money. For low frequencies a PC based scope might work, one that i know of is made by Parallax Linkage i have no experience with it but the specifications suggest it might meet your requirements. Moriquendi
Any of the cheap/free methods using a soundcard are very limited frequency-wise, there's one here using the parallel port that goes a bit higher, looks interesting, but to go way beyond audio frequencies costs $$$.
Wouldn't an analyser be more appropriate for troubleshooting serial comms. I know I'd rather use one over a scope for that.
I did consider a logic analyzer, but the signals I'm dealing with are both TTL/CMOS and RS232, via a MAX3232 chip, so ideally I'd need both. That BitScope looks awesome, do you have any experience with it? Might have to seriously consider one over the summer... Or, other similar suggestions would be appreciated.. Say a maximum budget of £300, PC based would be better than standalone, as I'd generally have a laptop with me anyway. That Parallax would probably do, but if I could get the BitScope one for £250 over the summer, probably worth waiting....
I don't have any experience with the BitScope but am currently considering, actually very close to, purchasing it. I just use the oscilloscopes at my university's labs but carrying my project back and forth is becoming a pain - especially on a breadboard.
If your trying to capture a long series of comm signals (not the quality), then you should use docklight. You can capture serial signals of any type/baud and doesnt require any more hardware than your serial port. If you want to capture the quality of the serial signal, any cheap oscilloscope will do, and not storage either. I fixed a $50 Tektronix 50MHz scope from Ebay and use it for serial signals all the time. There is no storage capability. I program a PIC to send a 3 byte sequence repeated on a kind of duty cycle. Example: Baud rate of about 56k @ 8N1. 10 bits per byte (start +8+stop). Thats 5.6K/byte or 1.866k/ 3 bytes. I repeat the sequence every 5 ms. It takes a little over 0.5ms to transmit the 3 bytes. The scope captures the first byte transition as the repeated signal trigger, and using the range dials I can easily tune into the 3 bytes on the scope.
I have heard very good things about this: http://www.pctestinstruments.com/ its a USB 34 Channel 500MHz Logic Analyzer with more features than you can poke a stick at. Perfect for debugging serial comms etc..
"cheap" and "Oscilloscope" are not words that can be used in the same sentence. there is only "crappy" and "expensive"
Nope! "Cheap", "Oscilloscope", And "Surplus" are very compatable. I have an excellent Philips (PM-3232) dual beam 10mhz scope from the 80s that I got for $12 at a Ham radio rally (And they had a lot of cheap scopes). It doesn't have any really fancy features (no storage, etc...), but it does analog very well, and I can manage to do digital debugging provided the signal is repetitive. It's easy to work with, and everything works perfectly. It's accurate, too. You can get really nice oscilloscoped off ebay for $50 on a regular basis, provided you don't want something really high end (like a DSO or something). Hell, I've seen a military surplus (analog) storage stope going for $75 on craigslist.
I decided to poke around on ebay to see if I could find anything good and found this... http://cgi.ebay.com/Tektronix-TDS74...91965990QQcategoryZ104247QQrdZ1QQcmdZViewItem $23k oscope with an article for it written like its for a person who doesnt know what an o-scope is
I'm betting they got the scope in a bulk surplus buy or something, and just grabbed the first definition they could find when they searched for "Oscilloscope". The "digital phosphor" thing is pretty funny.
