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#144223
Thanks for the example. I figured you would use a logic analyzer to decode serial messages but now I can see (edge timing) why an o-scope is important too. What do you think of the cheap Rigols?

Dan
#144225
dkulinski wrote: What do you think of the cheap Rigols?

Dan
Not bad actually ! All you can expect to get at about $300 is 2 channels, 40-60 Mhz bandwidth and 8 bit sampling. Look at the specs for the DS1052E which was being compared to the MSO-28.
http://www.rigolna.com/products/digital ... e/ds1052e/
It's a much better o-scope but it is just an o-scope, no LA included. Rumor has it that the low end Agilents are nothing more than repackaged Rigols with the HP ... errr, Agilent markup. :mrgreen:

In the end you have to decide what it is you really need. If you're doing a lot of analog work, I can't imagine a hobbyist needing (or affording !) much more o-scope than the above. OTOH if what you do is a lot of digital perhaps it would be better to have a "toy" o-scope and spend the $$s on a logic analyzer like Saleae Link. ($150)
http://www.saleae.com/logic
http://www.sparkfun.com/products/8938

And if you don't do all that much and/or are on a tight budget get something like a Bus Pirate and a "toy" o-scope (like a Nano) all for less than $150.
http://www.sparkfun.com/products/9544

As an intermediate compromise the MSO-28 isn't all that bad ... it just depends on your needs.

Afterall having something adequate to see what's going on for 80% of your problems is better than having nothing to see for 100% of your problems. :mrgreen: I keep thinking that that's what I should do ... buy cheap and then borrow stuff from work for those times when I need more.
#144247
Definitely a big "Thank You" on my end. I've flat-out never used an oscilloscope before. I had an old automotive oscilloscope, but could never find a manual or even figure out if it worked in the first place.
#144662
My laptop is on the way back.

What do you folks think of this USB oscilloscope?
http://www.bitscope.net/store/?p=view&i=item+4

I'm at the level where I need an "all-in-one" master of none, but I'm worried that I'm going to need a critical feature for this project, that this thing doesn't have. Any chance you could take a look at it and see if anything is glaring? (I'm looking for advice, not guarantees)
#144686
I think you can do a lot better for the price ... for any of the products on that page. The hobbyist 'scopes sample at 40 Msa/sec which should give you an analog bandwidth <10 Mhz (and I'm being generous). For the same $300 you could have the Rigol talked about above, a much better device. I"ll see it I have some time to write up what I think the min req's are for a 'scope. But from what I've seen it looks like there are 2 catagories for the beginner, something like the DSO Nano for $100 or something like the Rigol for $300, with nothing inbetween. My quick take is a 1 channel
scope will be too limiting too often, 2 channels is a min requirement. Storage is a must. For debugging simple serial interfaces, a 'scope is good enough, a logic analyzer is nice but not necessary. Bandwidth is what you pay for, as it drives faster A/Ds, more memory, etc, etc. For entry level perhaps 2 Mhz might be enough. That'll put 10 samples in 1 period of a 200 kHz waveform. 10 samples should give you an good idea of what that waaveform really looks like. If you want to look for glitches or deal with faster waveforms, you'll pay more $$s. The sweet spot seems to be about $300. 40-60 MHz of BW is pretty good and you'll pay a lot more to get to 100 MHz.

FWIW I saw the following over at HaD and thought it might be worth a mention.
http://codeandlife.com/2012/05/16/world ... zer-for-5/
#146243
I definitely owe some pictures and an update.

The update is really more griping. I've got the Arduino end of the system reporting information over the serial link. Getting the display to read the link and update the display correctly is another issue. It's a different programming language, and I just don't get it. My plan is to start playing with the language from a "Hello World" point and continue on from there. I'm actually not trying to do anything too complicated (none of this project involves rocket science).

RL is a real pain right now. We were trying to buy a house (I have the down payment, I have decent credit, but apparently I don't make enough money, even though the mortgage would be less than the rent), that fell through, so we're moving to a smaller place (goodbye workshop), and I'm pushing for a job promotion.

Still, this project should have moved forward by now.
I need to get photos of my rig up. I found something interesting with Legos, that may be worth a write-up on its own. I just need to get my camera out and do some notes.

I still think the uOLED screens are the way to go. They're insanely flexible, but this means that there are tons of bells and whistles to set-up. Once the "bones" are built, people will find interesting ways to attach meat to them.

I did just get another Futurlec order in (This one was close to three months in coming... Nice stuff, but order early). In it was a cable crimping tool. I figured out that I can't crimp .1" terminals manually. This tool is going to let me build some better connections between the barrel sensor cluster and the mainboard. When I do go back to working on the chrony sensor, we should get better results (Two wire connections per cable as opposed to 8 with the current system).
#146248
Yeah the home loan scene is really messed up right now, I hope you can find a lender willing to work with you.

Glad to hear the serial stuff is working. That is always nice. Got my LCD to work on my lasertag setup. Now I can output info as I need it.

As for Futurlec, yes, they can delay shipments if something is not in stock. You can email them and usually get partial shipments if they have the stuff you need.

Were you using lego to build structure for part of the prototyping?

Dan
#146369
I know you spoke about getting an O-scope, I just picked up an old Tektronix 465M in perfect working order. Found it on craigslist, I setup a "recipe" on ifttt.com to email me whenever an oscilloscope showed up for $200 or less. I paid $150 and tested it tonight.

So you can find an old analog oscilloscope pretty cheaply that has a lot of bandwidth for these simple projects. I hooked it up to the crystal on the lasertag prototype and I was able to see a 16MHz wave, very very neat stuff!

Of course I can't play back samples but I setup a simple sketch to run a PWM on the arduino and I watched the falling and trailing edges and was able to see just how noisy those edges were.

Now I think rather than a DSO I will go for a logic analyzer next. There are a couple of them on Sparkfun and I think that will be what I pursue. Hopefully that will give you some insight on an o-scope purchase.

Dan
#146380
I ran across an open source logic analyzer project someplace. Turns out that SFE sells the hardware (at something of a markup !). I'm not sure how capable the whole system is but the reviewer I was reading had good things to say about it. I think (for a few less $$) it hits a good compromise on price and performance for the general hobbyist.

http://www.sparkfun.com/products/9857

http://hackaday.com/2010/02/28/open-sou ... nalyzer-2/

http://dangerousprototypes.com/category/logic-analyzer/
#146382
dkulinski wrote:I know you spoke about getting an O-scope, I just picked up an old Tektronix 465M in perfect working order. Found it on craigslist, I setup a "recipe" on ifttt.com to email me whenever an oscilloscope showed up for $200 or less. I paid $150 and tested it tonight.

So you can find an old analog oscilloscope pretty cheaply that has a lot of bandwidth for these simple projects. I hooked it up to the crystal on the lasertag prototype and I was able to see a 16MHz wave, very very neat stuff!

Of course I can't play back samples but I setup a simple sketch to run a PWM on the arduino and I watched the falling and trailing edges and was able to see just how noisy those edges were.

Now I think rather than a DSO I will go for a logic analyzer next. There are a couple of them on Sparkfun and I think that will be what I pursue. Hopefully that will give you some insight on an o-scope purchase.

Dan
Funny, I did the exact same thing. I love ifttt.com. I'm getting hits, but I haven't found one yet that is both in my price range and with the features I think I need.
#146397
Glad you know about IFTTT then. I found out about it two weeks ago and happened to stumble on that 465M.

As for the logic analyzer I think I may just save up for the Saleae Logic16. It has good reviews and can run two channels at 100MHz.

Dan

EDIT: Alright I took a bit of time and looked at the Open Logic Sniffer. This thing actually does look very good. I may just purchase that. Sparkfun is a bit more pricey but they also have it locally, I can always run up and pick it up.
#148138
OK really long overdue.
I thought I was moving to a nice new place. Instead we've moved to a townhouse... I'm not going to be able to do that much "live fire" testing. The sort-of good news is that I got a promotion. I've got a little more money to throw at this. I'm looking at an oscilloscope on Saturday. The flip-side of the promotion is that I've got less time to spend on this.

I'm still going to poke at this. I may try to switch over to an Arduino Leonardo, as it seems to offer some slight speed advantages. I don't have one yet, but that's going to happen at some point.

I'm going to take some time to improve the documentation on this project. I'm hoping that someone with the space to pursue this will pick this up, and I'd really like to support that endeavor.

To that end: Anyone looking at building their own airsoft computer and happening across this project, please use anything you can find that's useful. I'd appreciate attribution, but I'd appreciate recognition for Mee_n_Mac and dkulinski even more. They really drove the project and provided critical insight when I was flailing.

I'm definitely not abandoning this project. I still think it's a great idea, I just can't work on certain parts with any measure of safety (my new place is really small. I don't have a workshop, I have an office chair).
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