USB Oscilloscope Interface - Page 1
Forum section: electronics / projects

author: JackP
author_rank: Regular Contributor
timestamp: August 02, 2015, 11:28:11 pm
content: I was thinking a while back about the reasons USB scopes are generally frowned upon here. Two such issues are the build quality and input range offered by the cheaper Hantek et al. models. Quality brands like Picoscope (and I'm not just saying that 'cause they sent me a free unit!) solve the first problem (although they command greater prices), and I BELIEVE their higher-end models have a greater input range. Anyway, the other main problem with them is the UI. Pico have the best UI IMHO, but still an application is AWFUL compared to a tangible, hardware interface. This brand in particular are focusing on a different market (people embedding the scopes in designs), but see the bottom for more info.So yeah, my idea is pretty self-explanatory. Essentially, a control panel with all of the regular controls you would find on a regular scope, attached via USB. I've got my implementation down, I'm just going to configure the device as a HID (keyboard) and send keypresses over USB (the great thing about Picoscope is they allow you to create a custom keymap, which you can export or import). Obviously, I could just go with an ATmega 32u4, use the Arduino bootloader and use the library. But I don't really want to go that route for a professional product, even if for no reason other than pride in the code. Moreover, that is the ONE library I can't find the source code for (to extrapolate the programming methodology). Also, that chip is relatively expensive (~£2 in volume) which wouldn't be awful if it speeds up dev time, but I don't need much besides USB to poll a few buttons and encoders. I am looking at the STM32F070CBT6, a value line STM part with built-in USB peripheral, for ~92p in 1000 of quantities. My issue is, having read through the relevant parts of the datasheets (both parts), and read some of the USB app-notes, I still can't make head-or-tail of it. I'm not asking anyone to write code for me, but I do believe this task is beyond me at the moment, and I'd like your opinion whether it is OK to utilise the Arduino library, or if I should go about finding some framework to get it working. My main issue is how to get the device to register as a HID, let alone sending packets of data. I looked into the FTDI solution, but they are fairly expensive (I recall someone (Technix maybe?) made a fused UART-USB adapter with a different IC, but I can't remember the name).Anyway, I like to think I'll find a way to get it working, even if I have to resort to the Arduino source for Rev. 1! On a less technical note, I'd like to see whether this is a device people would buy. Can you see yourself or a significant portion of the (technical) community looking for something like this? In addition, what would you look to pay for a device like this? Obviously it's a fairly niche product, but the niche in question is really quite big, so that could be a factor in regard to pricing. If you read below about my communications with Pico, you'll know my main argument was that the thing holding back hobbyists from their scopes (besides price, but some are willing to pay more) is the UI. As such, would the presence of this device tempt you into purchasing a USB scope (if executed well). I'm going about this as a sort of market research, to ascertain whether the points I put across to them which I have inferred through scavenging the forum are true. A final question, if anyone has any experiences with any other USB scope software, do you know if they also gain input from a keyboard?I've talked about my idea, and I'd like to know your opinion, but I also contacted Pico (BTW my fixation on them stems from the fact that they are situated in my home town). My main goal was to try and sort out a kind of collaboration on this product, so they might consider selling this product under their own brand (PicoInterface?!). They were having none of it, and I was told they had a policy not to develop a hardware interface. Instead they were 'investing in a tablet app to capture the growing market of mobile devices'. I refuted this by saying they didn't actually have to invest anything, and that a touch screen is not much better than a PC screen for usability. In reply to this, they mentioned that their main market is professionals, who embed the scope in a product. Fair enough, I thought, and then proceeded to tell them that increasing usability could gain them a share of the hobbyist market. Anyway, no reply yet!I just thought I'd share my experience as a side note, but I would love to hear your opinion, in regard to my questions, USB scopes, the device in general or my experience with Pico. Thanks a lot!

author: ataradov
author_rank: Super Contributor
timestamp: August 03, 2015, 01:57:45 am
content: It will feel weird without having the controls on the same surface as the display. So I don't think it will actually work all that well in a mass market.The same thing happens with pen tablets. In theory, you could do so much, but in practice it is not like regular drawing at all. It takes a lot of time to get used to. And while it is worth for the artists, since drawing with the mouse is keyboard is basically impossible, I'm not sure it is worth the time to adopt to this for a scope.

author: pickle9000
author_rank: Super Contributor
timestamp: August 03, 2015, 02:07:48 am
content: Quote from: ataradov on August 03, 2015, 01:57:45 amValid point, so make it so it can attach to the monitor. Use the wall mount screw holes.

author: ataradov
author_rank: Super Contributor
timestamp: August 03, 2015, 02:09:56 am
content: And how is that going to be better than using a normal scope?

author: pickle9000
author_rank: Super Contributor
timestamp: August 03, 2015, 02:40:36 am
content: Quote from: ataradov on August 03, 2015, 02:09:56 amIt's not better, just a design observation.

author: pickle9000
author_rank: Super Contributor
timestamp: August 03, 2015, 03:55:15 am
content: I wonder if a gesture device like thishttp://www.dezeen.com/2015/06/02/google-project-soli-interaction-sensor-radar-hand-gestures-digital-control-electronic-devices/would be accurate enough to work off a dummy board? That is a board with knobs and such but not connected.I have used a touch screen with a usb scope, works ok. They are very portable excellent to have in the bag.

author: rs20
author_rank: Super Contributor
timestamp: August 03, 2015, 04:06:37 am
content: I think the problem is standardisation -- there's a hundred different USB scopes out there, a hundred different bits of software that are almost universally terrible (even if they *did* have a good hardware interface), and you're throwing some hardware interfacing into the mix. I suppose if you're lucky this software has hotkeys that your "keyboard" can "press"?And even a DS1054z has an FPGA caning through the data taking ADC data in and driving the display directly. You just can't compete with that (in terms of waveforms per second, etc) with a USB link in the mix, especially with the DS1054z as cheap as it is.

author: pickle9000
author_rank: Super Contributor
timestamp: August 03, 2015, 04:43:03 am
content: I think the comparison isn't a fair one I have a usb scope but 3 conventional scopes. Each purchased for a particular purpose. A fair argument is that if the cost of a knob board is 10 bucks would you buy one? I probably would just to try it out. If on the other hand it cost 200 buck then not a chance.One interface option I've always wanted and have experimented with is a [single/auto/start stop] remote for my DSO's. Basically to allow me to speed up probing while troubleshooting.

author: miguelvp
author_rank: Super Contributor
timestamp: August 03, 2015, 06:13:05 am
content: I like this. I wanted to use a Dell Venue 8 Pro with my Analog Digital Discovery and use a PSoC 5LP to take care of the knobs and buttons to control the software via HID.Only downside was being able to charge the tablet while using a USB hub for the peripherals, but I found there are some solutions out there for that.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 03, 2015, 07:37:06 am
content: Something like this is done with Software Defined Radios.The diehard computer freaks have no problem with the use of a mouse,etc,but many people like the betterfeeling of control which is available with physical knobs.The SDR makers have given up trying to "educate" a large portion of their potential customers,& now offerthis option.

author: JackP
author_rank: Regular Contributor
timestamp: August 06, 2015, 09:59:09 pm
content: So people would be willing to pay a low price, but don't think it will be overly useful. I suppose then it won't push anyone towards buying a USB scope (take into account the price difference, portability, ease of data extraction etc.)? Thanks for the replies thus far.

author: Lukas
author_rank: Frequent Contributor
timestamp: August 06, 2015, 10:26:00 pm
content: Actually, there is a USB scope front panel: DPO7AFP by tek, unfortunately it only seems to come with a $300k scope...

author: MarkF
author_rank: Super Contributor
timestamp: August 07, 2015, 12:58:11 am
content: Quote from: JackP on August 02, 2015, 11:28:11 pmIt doesn't matter how much you dress up a pig. You still have just a pig.Compare the specs. Compare a Pico 2206A 50MHz 2 channel scope for $409.00 and the Rigol DS1054Z 50MHz 4 channel scope for $399.00 at tEquipment.Pico 2206A Rigol DS1000Z-------------------- --------------------Sample Rate (2 channels) 250 MSa/s 500 MSa/sWaveform capture rate 5700 wfms/s 30000 wfms/sMemory Depth 32Kpts 12Mpts / 24MptsNo comparison. For a 50MHz sine wave, the Pico scope only gives you 5 samples. Not much detail (It could be a triangle wave). If you have a steady repeating waveform you could get away with the Pico scope. But if you have problems with glitches/non-repeating signals/data separated by long time intervals, you have NO chance of finding the problem with the Pico scope. You need the much higher capture rate and memory depth of the Rigol for example. A scope with deep memory is almost essential with todays microprocessor signals.