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dannyboy

Oscilloscope or logic analyser?

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Hi all. I'm looking at getting myself a piece of equipment for electronics - I have about $175 AU to spend, and I've been looking at getting an oscilloscope (a self-assembly DPScope) for a while. However, that budget perfectly fits a Saleae logic analyser. My question is - which do you think I should get as a first electronics tool?

 

I'm a uni student in computer science and mechatronics, so I'm thinking the logic analyser will be useful in future assignments - looks like I'll be working with lots of microcontrollers and such. But I find that the areas I tend to struggle with are the analogue portions of each circuit, so it'd be nice to have more than digital analysis. I'm also very interested in appropriate technology, or at least applying technology to low-tech situations, more than high-tech embedded stuff. And my multimeter is pretty cheap; it'd be nice to have a more precise tool at least for voltage measurement.

 

Common sense tells me that since this cash windfall is a gift, I should go with the more expensive logic analyser and save up for the DPScope out of my own wallet, but what do you guys think?

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The logic analyzer. That Saleae has saved me many hours debugging UART, SPI, and I2C issues, confirming that even if the target chip isn't responding I've at least got the peripheral configured right. It allowed me to determine the pre-programmed RF2500T from TI didn't conform to the bundled source code, by snooping to show me how it actually configured the radio. It handles inter-event time measurement by triggering on GPIO changes, and let me confirm the cycle delay counter in mspgcc was accurate.

 

Get a better multimeter with the change, if you're not happy with the one you've got.

 

Based on other discussions here and my own experience with the DSO Quad, a cheap scope isn't worth the money. (The Quad's a neat little thing, and if the interface was sane and it came with understandable instructions it might not sit in a box for six months between uses.)

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I'm relatively new to tinkering with electronics. Soon I felt like I would need an oscilloscope. I'm also still a student and thus, money is always a problem. My parents got me the above mentioned DS1052E from Rigol as a birthday gift (man I'm lucky). Not much time went by until I was sure I would also need a logic analyser. Of course I bought that very good Saleae Logic. Now (after 3 months) I can say that I should've bought the Logic first. I can check almost everything I need with the Logic. I really recommend you to buy the Logic first. Then, please do yourself that favour, save your money for a real o'scope like the DS1052E or better. Don't waste any more time on even thinking about something like the DPScope.

I hope this helps :)

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Thanks for the input, everyone! It seems pretty much settled - I'll go with the Saleae for now. I think I'll look for a second-hand CRO as recommended on the EEVblog - I was going to do that last year but I got out-bid.

 

Fred: the Scanalogic looks good. I'm going to see if there's any comparisons between the two online.

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I know this is an old thread but I'm finding myself drawn to the Rigol DS1052D (the DS1052E plus a built-in 16-channel logic analyser). General advice on the 'net seems to be to go for a DS1074Z (newer 4 channel 70-MHz scope) instead, but I like the idea of combining the scope and logic analyser and also not needing the PC for the display.

 

To be honest I find myself mostly doing logic stuff, but it'd be nice to be able to check the quality of one signal whilst just monitoring the status of others. If I'm really honest I can probably get by without a scope at all, but you know... just... toys.  :smile:

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Just FYI: based on a customer survey I got a couple days ago, I'm expecting Saleae to announce a new product real soon now.  The questions implied that it might be scope-ish in nature.

 

I don't use my Logic8 any more, but that's only because the Logic16 is all around better; I've got it up pretty much any time I'm working at low level on a micro-controller.  But then I don't do enough analog stuff to get much value out of a scope.

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@@Fred I just popped the $$$ for the 2000 series Rigol analog only. For many things, you don't need the full logic analyser. But I looked very hard at the 1052D. Very hard. I thought about my needs, desires, and what I currently have on hand. Then I went for the 2000series without logic. My needs are not the same as yours.

 

Some questions to ask are:

How many channels of logic are you likely to need? Do you need the ability to trigger on complex logic signals or do boolean operations for triggering? Do you need a deep memory for logic monitoring? Do you have a need for analog?

 

For me, the answers were not many, sometimes, rarely, and yes This said maximize the return for analog, and keep using the computer connected device for complex digital.

 

I happen to have old machines around that I can dedicate to various things (just ended up with another.... had to upgrade the shop computer to WIN8 (extortionary upgrade: software disabled itself until upgrade, but win8 only.... Won't mention the software, but at about $2K with no term on the license, I found it to be unconscionable), and I found it cheaper and easier to just pop the $$$ for the least expensive I could get that would do the job than to resystem the existing machine), so it isn't a handicap to me to use the computer for logic, UNLESS I end up with a situation where I need to do triggering for analog based on logic, or vise-versa. I don't expect to, but if I do, I can find a way to force the data grab and match things on the computer after the fact. Won't be able to do it real time.... at 2GHz, a few microseconds of latency for com between the devices is a good bit of any but a real deep buffer.

 

You may find it cheaper to go with the analog option and dedicate an old or cheap computer to logic so as to free up your main machine. You'd be amazed what you can do with a $50 yard sale computer that is a few years old. Not top of the line, but for dedicated tasks, often can't be beat.

 

Or, for some sets of answers, the Rigol analog units, and some other makes, do have logic options for I2C, etc. that will monitor, decode, and do fairly impressive triggering. Pretty much tied to a single input for these things, so no triggering on a memory bus address, but if you don't need that, then might be worthwhile. Comes as a time-limited freebee with some models. Costs some $$$ for permanent, though I would be surprised if no one has figured a hack for it. I neither encourage nor discourage hacking it.... It is between you and your concisece.

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@@enl Thanks for you input, which echoes a lot of what I found online. I'm starting to chance my mind too.

 

Looking further into the DS1052D it has a couple of missing key features which could be a deal-breaker. The analog and digital inputs are not completely in sync - almost but not quite. That to me would be a major plus point of a combined device. There's also no decoding of the logic analyser input. Even my cheap Scanalogic has this. This might be a purchase worth taking some time over.

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Def worth taking time over. It is a lot of money, unless you have elephant VC $$$ to blow. You need to identify what YOU need. It probably isn't the same as what I need. I am happy with the 2000 series Rigol so far, and don't anticipate needing to buy another scope for a good number of years. After all, my old one was over 50 years old, analog, nominal 500KHz, and it has done a LOT of work including debugging 10base2networks, which was way out of the spec for the scope. But I also use a low end 16channel logic probe plugin for the computer when needed (unbranded. I thing I got it from Jameco? Or maybe electronixexpress? It was several years ago to upgrade the old 8 channel parallel port device I used). Not needed often for me.

 

As I side note: I am still not up and running 100% with the Rigol. WIN8 issues, not Rigol issues. I hate Win8. Really, really hate it. Punch cards on an IBM360 and paper tape on a PDP10 were easier. Yes, We had computer connected logic probes and scopes back then.

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I realise I'm mostly talking to myself (and enl of course) on an old thread, but I thought I'd summarise what I've found looking into the lower end of the 'scope market.

Rigol still seem to be the value manufacturer to go for. They don't seem to be trying to close the hackability of their scopes. Maybe they realise that the person who will invalidate the warranty by upgrading their cheap scope isn't the same person who would buy the more expensive version. And the free publicity isn't bad. Everyone's heard of Rigol since the 1052E was hacked.

  • The DS1052E has been around a while and is likely to be retired soon. If you're really on a budget the prices are now even better. Still a good starter scope.
  • The logic analyser bit on the 1052D is not great. 16 channels sound good, but there's no decoding and the digital are not sync'd to the analog channels.
  • The DS1074Z seems to be the new 1052E. Reasonably priced. Has 4 channels (although the bandwidth drops when you use them all). Can have serial logic decoding (UART, I2C, SPI) upgrade if purchased or hacked. Also hackable to a DS1104Z (100MHz) like the 1052E.
  • The DS2072 is the one to go for if you want a slightly better scope and are prepared to pay a bit more. Also hackable to be a DS2202. (The A version might not have been hacked yet.)

 

Anyway, that's just what I found. Plenty of people will have different opinions and there are definitely better manufacturers than Rigol if you're not looking at the value end.

 

I think I'll go for the DS1074Z but unfortunately they don't seem to be in stock anywhere in the UK for another month. It'll give me time to change my mind anyway.

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