Red Pitaya for a beginner - Page 1
Forum section: electronics / general

author: newman89
author_rank: Newbie
timestamp: July 07, 2014, 12:45:44 am
content: Has anyone gotten their hands on a Red Pitaya and put it through its paces?I have looked around and can't find much in terms of reviews and what I can find is very basic.Would it be worth getting one or would it only really be useful for simple projects.For anyone that doesn't know what I'm talking about:http://redpitaya.com/Cheers

author: QuantumPhys
author_rank: Contributor
timestamp: July 07, 2014, 03:33:58 pm
content: Hi,I do not actually have the board so do not take my word for it.I have been following the project since its kickstarter, and I feel that even though the software seems nice, and the hardware is of good quality, the thing is still quite under-speced , making it "just another USB oscilloscope". It may be interesting if it is cheaper, but at $470, you can get a HP logic analyzer plus a Tek 2465B plus a function generator!Again, someone who has this board would give much better advice.

author: robimarko
author_rank: Regular Contributor
timestamp: July 21, 2014, 09:32:15 am
content: They are bragging that it is open source but there is absolutely no schematics or part lists avaiable

author: Dolganoff
author_rank: Newbie
timestamp: September 08, 2014, 12:49:38 pm
content: I've asked the same question once on their G+ page, nobody responded...As I understand (maybe I am wrong), the Open Source part doesn't refer to hardware at all, but to the applications they would like us to write for their platform...

author: jeremy
author_rank: Super Contributor
timestamp: September 08, 2014, 02:58:00 pm
content: I've got one. The HDL code is out there, and it seems to be quite well made physically. Heatsink on the Zynq is decent too.I'm really interested in using it for its fast adc connected to an FPGA (for DSP), as well as the ability to do some linuxy stuff at the same time. I'd like to make very specific instruments, I don't really care about it being an ethernet oscilloscope.I think you can write code for the Zynq-7010 using the free version of xilinx vivado, so that is probably what they are expecting you to do.I guess if you use it with its stock configuration as a 50MHz scope, it probably is not a wise investment at that price. I bought it so that I don't have to solder BGAs on my own pcbDefinitely not a good idea as a beginners device.Happy to try and answer any specific questions you have.

author: charlespax
author_rank: Regular Contributor
timestamp: September 12, 2014, 01:08:25 am
content: Quote from: robimarko on July 21, 2014, 09:32:15 amIf development isn't done in the open, I really don't consider it open source. Even the Beagleboard folks just havereleases on Github.

author: Howardlong
author_rank: Super Contributor
timestamp: May 03, 2015, 11:06:48 pm
content: Quote from: wilfred on May 03, 2015, 10:47:54 pmBlimey. half price, not sure what to make of that.

author: jeremy
author_rank: Super Contributor
timestamp: May 03, 2015, 11:29:30 pm
content: Well, after playing with one of these for a good part of a year, I'd say that you shouldn't get one of these unless you have a decent vivado license. Also, the schematic and board layout are not released, and the system code is very unmaintained (I had to compile my own fsbl and uboot so that it would work with a reasonably recent kernel, so I ended up throwing away their code). I tried to mainline my uboot port, but I think the board was a little too proprietary to have it accepted.However, as a zynq development kit for $266, I'm considering buying one for me (the one I have is for work). It's the closest thing to an open source oscilloscope that I've been able to find so far, and if you want to do some fast dsp then it is also one of the cheapest. It's definitely cheaper than putting an fpga and add/dac combo on the board yourself (those three chips alone add up to about $150).Perhaps they are half price because there is a new one coming?

author: janoc
author_rank: Super Contributor
timestamp: May 04, 2015, 12:09:46 am
content: Quote from: jeremy on May 03, 2015, 11:29:30 pmOr the existing one isn't selling for that price ... It is seriously niche device.

author: tggzzz
author_rank: Super Contributor
timestamp: May 04, 2015, 08:19:52 am
content: Quote from: newman89 on July 07, 2014, 12:45:44 amMy feelings, as someone that has looked at it but doesn't own one, is that:it is an excellent way of getting hold of an FPGA+ADC+processorif you want to understand/modify the internals of an oscilloscope, it is unparalledif you want to investigate tight low-latency feedback from an ADC to DACs etc, then it is unparalleledFPGA development is possible and this provides a good starting pointFPGA development is not for the faint-hearted; it requires time and determinationthe ground connections for the digital signals on the extension connector are poor, unnecessarily poorthe hardware is closed-source to an unnecessary degreethe originators are accessible through their forumsas a general purpose scope, there are better alternatives - no surprises there!

author: tggzzz
author_rank: Super Contributor
timestamp: May 04, 2015, 08:32:04 am
content: Quote from: wilfred on May 03, 2015, 10:47:54 pmRS has similar offers.

author: jeremy
author_rank: Super Contributor
timestamp: May 04, 2015, 08:36:20 am
content: Quote from: tggzzz on May 04, 2015, 08:32:04 amNot similar for us AustraliansDown from $505+tax to $454+tax.

author: charlespax
author_rank: Regular Contributor
timestamp: May 11, 2015, 02:43:47 pm
content: Are there any opensource hardware alternatives to the Red Pitaya?

author: jeremy
author_rank: Super Contributor
timestamp: May 11, 2015, 08:43:22 pm
content: Not that I know of. I'd definitely pay a bit for a board with a similar fast adc, fast dac and a zynq 7020, as long as it was properly open sourced.I don't really know why they didn't open source it; if they were worried about profit, it's not like I'm going to get an 8 layer board full of BGAs fabbed myself anyway... It would cost a truckload in low volumes

author: tggzzz
author_rank: Super Contributor
timestamp: May 11, 2015, 08:50:47 pm
content: Quote from: jeremy on May 11, 2015, 08:43:22 pmI don't think the designers are worried about people like us!

author: Xykon
author_rank: Newbie
timestamp: June 04, 2015, 12:12:28 pm
content: I backed the SmartScope on Kickstarter which was running at about the same time as the Red Pitaya. RP was too expensive for my taste so I went with the SmartScope which was promised to be completely open source. Well it turned out LabNation went back on their word... they're not going to publish details of the analog frontend on their scope and also the GUI won't be fully open source... even though it is heavily based on open source components. The GUI right now is absolute garbage so the thing is mostly useless. I think they could have gained a lot by publishing the sources... once again a good idea was crippled by stupidity and greed.I finally decided to order a Red Pitaya from Elektor... I ordered it with the case though which delayed my order... they are now sending me the Red Pitaya first and will ship the case for free once it becomes available. Should arrive in the next few days and I'll be looking forward to checking it out.I do have an old bench scope and spectrum analyser but they take a lot of space plus generate a lot of noise so I'd love to replace them with a small portable instrument. Of course I don't expect the Red Pitaya to be as powerful as these professional instruments but if it can help me with some basic tasks that would already be a big win. Can always setup the big instruments when I really need their superior power.

author: miguelvp
author_rank: Super Contributor
timestamp: June 04, 2015, 04:51:13 pm
content: Hmm, seems they are releasing the information, but might take them a while:http://wiki.lab-nation.com/images/a/ab/SmartScope_-_Schematics_-_v1.0.pdfhttp://wiki.lab-nation.com/index.php/SourcesSeems the forums have more information as well.

author: 1design
author_rank: Regular Contributor
timestamp: June 22, 2015, 05:52:10 am
content: As I mentioned in another post Red Pitaya was not primarily designed as an instrument as such, more of a dev. platform, like the Arduino, so people can do their own things with it, not just stick to the few "downloadable" applications. Think about what you can learn by using it as a tool, modifying the FPGA and SW to suit your need for signal acquisition, processing and generation. If you add a shield with a few RF components you a get an SDR with 60MHz real time BW for example etc.Even if you don't know how to do these things this is a good tool to learn this, with this knowledge you get additional value to your professional skillset so more jobs are now available as this is an advanced set of skills that not many have.Best Regards,Miha

author: piranha32
author_rank: Unknown
timestamp: August 01, 2015, 09:10:52 pm
content: Quote from: newman89 on July 07, 2014, 12:45:44 amI've got RP on Kickstarter, and I'm disappointed. The idea is very nice, but implementation - not so much. I'd have a lot to say about very crude official software, not improved much since the first release making the tool more of an educational toy than a real measurement instrument, short buffer, etc. However, the most important reason for me to leave it on a shelf is noise. The image below shows how the spectrum of the signal from ADCs looks like with no signal connected to the inputs (inputs terminated with 50ohm SMA terminators). 25dB spike at 2.3MHz, a bit lower one at second harmonic, plus quite a bit of noise at low frequencies. Of course it is well visible as noise on scope view, making RP useless for measuring weak signals.

author: daveatol
author_rank: Regular Contributor
timestamp: August 02, 2015, 12:20:42 am
content: Quote from: piranha32 on August 01, 2015, 09:10:52 pmWhat's the range setting of the channel in your spectrum plot? If 0 dBm is the reference, the -84 dB noise floor fits in perfectly with the quantisation noise of 14-bit sampling. (Though the 2.3MHz peak shouldn't be evident, obviously)

author: piranha32
author_rank: Unknown
timestamp: August 02, 2015, 01:14:01 am
content: Quote from: daveatol on August 02, 2015, 12:20:42 amLow voltage (+/- 1V).

author: piranha32
author_rank: Unknown
timestamp: August 02, 2015, 02:07:01 am
content: Quote from: piranha32 on August 02, 2015, 01:14:01 amI just checked with "High Voltage" setting. The peaks remain the same, what indicates that the noise is not picked up by the input circuit, but appears somewhere closer to the ADC.

author: daveatol
author_rank: Regular Contributor
timestamp: August 02, 2015, 02:48:51 am
content: Quote from: piranha32 on August 02, 2015, 01:14:01 amWell, ±1.095V is 0 dBm.Quote from: piranha32 on August 02, 2015, 02:07:01 amThe ADC sample rate is 125 MHz, right? If the peak is at 2.5 MHz, then it's possible that the ADC is clocked by 2.5 MHz (which leaks into the ADC inputs) and uses a x50 PLL to get the sample rate. How did you measure the frequency of the peak?

author: piranha32
author_rank: Unknown
timestamp: August 02, 2015, 03:03:29 am
content: Quote from: daveatol on August 02, 2015, 02:48:51 amThe frequency is more of a "ballpark" figure. At this frequency the spectrum analyzer app detected the peak, and the exact frequency detected is 2.35MHz. According to the schematic fromhttp://wiki.redpitaya.com/index.php?title=External_ADC_clockthe system is clocked from 125MHz XO, so it's rather unlikely that the ADCs are clocked using lower frequency.

author: tggzzz
author_rank: Super Contributor
timestamp: August 02, 2015, 07:35:34 am
content: Quote from: piranha32 on August 01, 2015, 09:10:52 pmThere's another area where the implementation is unnecessarily poor: the signals and grounds on the external connectorhttps://www.eevblog.com/forum/microcontrollers/red-pitaya-hd-images-for-getting-the-schematic/msg541053/#msg541053All the "NC" pins were grounds, and they were were distributed amongst the signals - not good for signal integrity. And it is compounded by not being able to use LVDS on those pins, due to the choice of Zynq IO bank voltage

author: markd
author_rank: Newbie
timestamp: February 12, 2016, 11:57:30 am
content: I recently bought one and I now lament the other things I could have bought with the money I spent on the RP.The graphical IDE is not free.There's no IDE that's similar to Arduino.Connection to the RP is through the network, which is a royal pain in the arse for 2 reasons. 1- if your going to use it at work and don't have admin access to routers etc. 2. I found it very difficult to set up for a fixed IP Address.You would want to be very familiar and comfortable using LINUX to be comfortable using RP.I found the web page and Wiki contradicted each other to some degree.The Wiki page doesn't appear to be well maintained.When RP talks about beginners, they must mean University Student beginners, because the surely can't be talking about hobbyist level beginners.

author: 1design
author_rank: Regular Contributor
timestamp: February 13, 2016, 06:46:39 pm
content: Quote from: piranha32 on August 01, 2015, 09:10:52 pmI tried to check this but couldn't manage to reproduce, my spectrum is clean even without a termination, what you see is a screenshot without anything on the connector. Where you using a signal generator at the time on the transmitting channels? It could be a crosstalk issue?BR

author: piranha32
author_rank: Unknown
timestamp: February 13, 2016, 07:23:58 pm
content: Quote from: 1design on February 13, 2016, 06:46:39 pmNo signal generators, nothing transmitting anywhere nearby. The issue is 100% reproducible, at many locations, so the issue of interference from local noise sources can be crossed off the list.

author: sfox7076
author_rank: Newbie
timestamp: February 17, 2016, 02:53:31 pm
content: I tried to buy the calibrated Red Pitaya kit last week when it was on sale. They ignored my order and now want me to pay full price. After seeing this post, I am glad the order didn't go through.

author: Howardlong
author_rank: Super Contributor
timestamp: February 21, 2016, 09:23:23 am
content: I'm developing a supposed quick and dirty solution for someone and recommended a Red Pitaya rather than build hardware from scratch bearing in mind the short timescales and need to de-risk. I received the device on Friday. I got the board to work fairly quickly, but then to develop on it... not so much.Here are my thoughts to Red Pitaya.o Make the unit easily visible through the network with a hostname out of the box, don't rely solely on the end user having to go through hoops (admittedly small, but irritating) just to connect to board. Thank God it has a USB/Serial port.o The Visual Programming thing doesn't even work... I assume it/s a cloud development system, but I don't know as I click the link and bugger all happens. Tried a few browsers including Chrome, Firefox and IE in Windows and Ubuntu, nothing. The scope didn't work, nothing seemed to want to make the traces do anything other than flatline. The spec an works, but that was it.o Blinky. FFS, how hard do you have to make this? I've been at it since Friday on and off. It's now Sunday, I reckon I've had about eight hours at this, in between building various Linux versions in VMs to try to make the instructions work. I still can't flash a ****ing LED. Not in Python, not in C. And no, I'm not an academic outfit with cheap Matlab licences. Why can I not get a Blinky to work? the documentation is woefully out of date/wrong/doesn't tell you what versions of what to install. You end up pissing in the wind trying stuff out. I have now found out that they switched from soft floating point to hard floating point making their very very very long Eclipse instructions incorrect. All well and good having detailed instructions, that's appreciated and to be applauded, but when they're wrong because you've deprecated it..... well I think I'll leave it there.Their web site is all very flashy and whatnot, sadly the content is very broken :-(True, there are warnings that the instructions are inconsistent since a Sept 2015 release... but we are now five months later.With regret, as it stands it's hardly for a beginner if you want to use it as a development platform.

author: piranha32
author_rank: Unknown
timestamp: February 24, 2016, 06:25:03 am
content: I have an impression that the company has been hijacked by the marketing department. The default apps (especially what they call "oscilloscope") shipped with the basic image suck big time. They're enough to verify that the hardware works, but completely useless for everyday use. Even shady Chinese manufacturers of crappy oscilloscopes would be ashamed of them.While there was some justification for shipping such low quality apps at the beginning, especially with the Kickstarter units while they were still working on the software, including them with the new system image released recently is a disgrace. Of course you can purchase much better looking "premium" apps. You'll just have to part with €49 for the oscilloscope part, or €39 for spectrum analyzer on top of what you paid for the hardware.I don't deny Redpitaya the right to make money from selling software. It's a commercial company after all, not a charity; However they should fulfill first what they promised, and then look for ways to make money on extra options.

author: Howardlong
author_rank: Super Contributor
timestamp: February 25, 2016, 01:06:49 am
content: To put this into perspective, I finally got a blinky going this evening. I'd say that took about 25 hours of seemingly endless random button pushing when none of the instructions worked as described. Even then I had to compile the code on the board as there seems to be a problem with cross compiling shared libraries in the recommended toolchain, but that's just one of dozens of banana skins I encountered.

author: Carrington
author_rank: Super Contributor
timestamp: February 26, 2016, 07:57:37 pm
content: I'm curious, just to compare the noise floor, here are the results of one Analog Discovery I (worst case possible and nothing in the inputs):

author: Carrington
author_rank: Super Contributor
timestamp: February 28, 2016, 06:29:13 pm
content: Wow! Seems that the Red Pitaya has half noise floor that the Analog Discovery:And even so it round 5 mVpp.

author: Howardlong
author_rank: Super Contributor
timestamp: March 01, 2016, 10:42:04 pm
content: If you're lucky enough to get the scope app to work at all of course! No luck with that one here I'm afraid although the spec an seems to run.When travelling at the weekend, I used an Analog Discovery to debug code on the Red Pitaya. I can't imagine ever having to do it the other way around.

author: Carrington
author_rank: Super Contributor
timestamp: March 03, 2016, 08:02:21 pm
content: Quote from: Howardlong on March 01, 2016, 10:42:04 pmYeah, relative to the SW, the red pitaya is a different history (at least for now).For the Red Pitaya I guess that is a matter of time or money (if one want to buy the SW).With the Analog discovery one can put to work it quickly, just using the provided SW.I know that isn't easy to comply with the USB specification, but both devices have a lot of noise floor, a shame.It could be as good as this:But instead, you get something like this:

author: Howardlong
author_rank: Super Contributor
timestamp: March 03, 2016, 09:02:09 pm
content: It turns out that unlike the SA that comes with the Red Pitaya stable release, the scope app included with the "stable" build doesn't work. I had to install the one from their online store.To add insult to injury, for most of this week I've been unable to log in to their systems.Perhaps this is scare mongering, but I do have concerns about their business model. I think they were betting that they'd make their mint on their app store purchases. Like the Analog Discovery, there can't be much margin on the hardware once the retailers have had their pound of flesh.

author: Carrington
author_rank: Super Contributor
timestamp: March 04, 2016, 04:49:06 pm
content: Quote from: Howardlong on March 03, 2016, 09:02:09 pmHey! Red Pitaya team, takes note.Quote from: Howardlong on March 03, 2016, 09:02:09 pmMore than likely.

author: austnais
author_rank: Contributor
timestamp: February 28, 2017, 10:37:06 am
content: Hi guys. Not much interest in the Pitaya here!I have a sort of general question, but the application is a Red Pitaya. What do you use the RF outputs for? Say I want to drive a mosfet to create a switchmode application where adjustment of the dutycycle, frequency, waveform etc is really easy, is this possible. The output is only +-1Vpp so I assume it might be difficult.If not, what to use instead? A 555 will for sure do the job, but it's a bit tedious to modify for experimental work.

author: Kean
author_rank: Unknown
timestamp: February 28, 2017, 11:15:53 am
content: I have an RP, but I've never seriously used it beyond an initial play. It has been much easier to use my bench equipment than stuff around with a Linux environment with web interface and poor support. Maybe one day I'll have a specific application I can put it to so as to jusity the original purchaseThe RP Sig gen output would be used just like any other Sig gen. It can go up to 50MHz which isn't bad, but the output of only +/-1V (and no offset?) is a bit of a limitation.As a sig gen it can be used for their LCR application, or testing HF/VHF filters, etc.For drivng a MOSFET from either a 555 or a signal generator, you going to want to use a MOSFET driver chip - maybe something like the TC4428A (logic level input).You can get a MHS-5200A 25MHz sig gen which is more functional then the RP one for $70, and the MHS-5200P is similar spec but higher power (can put out 1A).I'd still use this with the driver chip as that would generally be needed in the final design.

author: austnais
author_rank: Contributor
timestamp: February 28, 2017, 12:11:45 pm
content: Thanks a lot Kean!Regarding the TC4428A, HIGH-threshold is 2.4V which means the RP is not enough just to drive directly. Can one use a pull-up to 5V on the line and let the pitaya sink the curent? Or does there exist a chip with lower HIGH-voltage threshold?

author: Kean
author_rank: Unknown
timestamp: February 28, 2017, 12:34:38 pm
content: Yep, glad you spotted that - that's why I mentioned "logic level input"A pull-up isn't ideal, as you want reasonably quick transitions from low to high, and that requires active circuitry. Also I don't recall the RP output circuit, but it may not like having the 5V pullup either.Personally, I'd suggest building a small output amplifier board for the sig gen that also lets you add a DC offset. It wouldn't have to handle the full 50MHz bandwidth, just whatever range you think you'll be working with. That would then allow you to take a signal from the RP, then amplify and offset it to say generate a 0-3V signal from the RP sig gen. You can feed it back into one of the RP inputs (in HV mode) to check it, and would be quite a useful general purpose add-on for experimenting I think. It would need separate power supply, something like +5V & -5V, depending on your desired output range.You'll want to read up on using opamps if you're not too familiar - something like this explains the concepthttp://electronics.stackexchange.com/questions/93423/how-to-amplify-and-offset-the-voltage-in-an-opamp

author: austnais
author_rank: Contributor
timestamp: February 28, 2017, 12:50:21 pm
content: Great! Op-amps is clearly the solution for me!Thanks

author: Kean
author_rank: Unknown
timestamp: February 28, 2017, 01:06:40 pm
content: Maybe just start with a common one likehttp://www.ti.com/product/TL072

author: boffin
author_rank: Unknown
timestamp: March 03, 2017, 06:11:40 am
content: it's not fast, but it's cheap, and at least the API is openhttp://www.nscope.org/

author: janoc
author_rank: Super Contributor
timestamp: March 03, 2017, 04:22:08 pm
content: Quote from: boffin on March 03, 2017, 06:11:40 amAt 4 megasamples/s you are going to be have difficulty to even debug basic SPI with that thing. That's a toy or perhaps cheap educational tool. Real usable bandwidth is going to be perhaps 400kHz and if all 4 channels are in use, 100kHz or so. Is is basically a PIC with some opamp buffers + DDS for signal generation.NScope doesn't come anywhere close to the capabilities of Red Pitaya or Analog Discovery. Open API is cool but of little use when the hw is not up to task. And it costs $100 on Amazon. That's fairly expensive for what it can do, IMO.

author: irakandjii
author_rank: Regular Contributor
timestamp: March 21, 2017, 03:54:28 am
content: I had one, (early adopter) found the performance had been overstated and the support terrible. At the time, the promised applications were buggy and the community very small.I really wanted it to work but, a tool should never consume more of your sweat and effort than the task for which it was acquired. It did!I sold it on ebay at a significant loss, and still happy I did..