Suggestions for logic analyzer/usb oscilloscope?

Other Hardware Science and Measurement
1

Hi -- I am very new to arduino, but had a friend help me with a problem... In his tool kit he had a small oscilloscope -- he didn't recall where he got it.

I have been poking around and there are a lot of options.

For general arduino, what is a good sampling rate? It seems the faster the sampling, the more it costs -- is there a point of dwindling returns?

I am a bit confused by all the terms usb-oscilloscopes toss about, but it seems I will learn more as I use it.

My budget is sub $100.00 (USD)

Any suggestions? I am not adverse to a 'kit' that requires soldering...

2

Save money for a logic analyzer from - https://www.saleae.com/ but it is above your budget.

You can build one yourself, start reading - SUMP compatible logic analyzer code for Arduino. - Interfacing w/ Software on the Computer - Arduino Forum -

also - Arduino logic analyzer with Logic Sniffer client – Dangerous Prototypes

3

Still the question -- how fast should I reasonably need?
Saleae has several versions...

4

Depends on your projects and platforms used.

The logic 8 is fine for Arduino as it can take more samples than Arduino (UNO/MEGA) can generate.

8 lines is also very convenient, e.g to monitor an I2C and some IO lines at once.

disclaimer: mentioned a product I own so I am biased :wink:

5

Thanks Rob!
There are a lot of 'self build' ones that are 1mhz, which I assume is optimistic.... There are others 10,12,5,20mhz etc... all over the map.. it's pretty amazing the varriety - like wines, hard to judge them when you dont' know any better.
I was looking at one of the SainSmart ones; but I'll hold out for saleae...

6

IMO a logic analyzer will be a lot more useful on a microcontroller than an oscilloscope would be.
You can get cheaper versions than the Saleae that have 4 or 8 digital lines and even run a poor man's one on the Arduino using code from here.

If you insist on an oscilloscope then depending on what your expecting to measure 20MHz might be suitable for AVR core chips but if your going to venture into the faster ARM cores then you may need as high as 100MHz and your not likely to get something that fast for sub $100. Google and you will also find Arduino based scopes.

7

Thanks Riva -- I want to get something usable & learn with/from it.. maybe in future I can buy better ones.
I am debugging some radio packets/noise and it seems a scope is the better choice for this...
I almost bough a bus pirate & open workbench analyzer, which both seemed fast enough for arduino work; but read many reviews that seemed like it had bugs & development sort of stalled.
A lot of the cheap/inexpensive ebay ones seem (to me) like they're trying to mislead by interchanging terms (sampling rate, vs bandwidth, etc)
It's very frustrating to weed out crap when I really don't know what is crap, or good for that matter. Even at the $150usd mark, it's still frustrating to get the details down in a comparable fashion for a layman.
Seems someone could make money by renting out a handful of options for people to try to see what fits their application best....
retirement (Nice for unemployed) is not all that it's cracked up to be -- very restrictive budgets, probably not the best time to pick up a new hobby :wink:

8

Logic analysers are completely blind to the quality of signal, I would always
recommend an oscilloscope as the tool of choice first - until you can see the
signal is clean you cannot trust the logic analyser one bit.