Expectations with RP

Just about everything about Red Pitaya
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ipisco
Posts: 6
Joined: Thu Nov 19, 2015 4:42 pm

Expectations with RP

Post by ipisco » Thu Jan 21, 2016 8:37 pm

So far after having some setting up problems with my RP (Thanks support! very well done) I’m starting to use my RPitaya and my comments are the following:
As electronic engineer with extensive experience in the electronic workbench I confess that my expectations with RP are not the same when I order this board.

1) With the RedPitaya I don’t have the same confidence and reliability that I have with my old oscilloscope. I don’t know if what I am measuring is noise or false signal or it is the real one. I don’t have handy some signal of reference. When I was using the generator with a square signal to use as reference, the only value of Vcc = 4.6V, only shows a noise with uncertainty values, but with a simple tester I could read a value or ripple and VCC.
2) With a Red Pitaya I don’t have the emulation of rotary dial as the normal oscilloscope, and for this purpose in RP to change the range take for ever to enter a new value. So far is a nice gadget but no practical. Example: If I want to see only the values of the ripple in some power supply, I found this task not easy to measure.
3) Per example I can’t see with RP low signal that trigger SCR or Triacs. Doesn’t have the controls to make versatile this measurement.
The user never knows when the real signal is present!
4) With RP the zoom or manipulation of the image are amazingly good, when you are certainly known the correct wave is present.
5) Offers the option to play with acquisition of signals but although still I don’t find any place with tutorials that teach how to do things from the start level.
6) RP advertise, that this tool is for beginners to engineers. Take as reference of Arduino in the level of tutorials that exist in the Arduino.org website. Hopefully the RP in the future will be with such support and examples ready to use. But please don’t claim that this tool easy to use. I don't purchase because was easy to use but is as good as a analog or digital oscilloscope.

So far I think this device is not complete. Only the process to update to a new version is terribly complicated. Should be automatic or manual but selectable and with a run button. Although it has so much potential to interact with other tools as Matlab or some simulator as Proteus. The price that they charge is high for what is put in the bench.

If you think otherwise, please point me in the right directions and attach some examples/links that could help everybody in this
Open to discussion

jeanminet
Posts: 33
Joined: Tue Aug 25, 2015 12:17 pm
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Re: Expectations with RP

Post by jeanminet » Tue Mar 01, 2016 2:36 am

ipisco wrote: The price that they charge is high for what is put in the bench.
If you think otherwise, please point me in the right directions and attach some examples/links that could help everybody in this
open to discussion
My 2 cents... If you were trying to build the Red Pitaya yourself you would need (as of March 2016) :
* a Zynq XC7Z010-1CLG400C : 55 € http://www.digikey.fr/product-detail/fr ... ND/3925789
* ADC (2 ch / 14bits / 125 MSps) LT2145 : 73 € http://www.digikey.fr/product-detail/fr ... ND/2699163
* DAC (2 ch / 14bits / 125 MSps) DAC1401D125HL : 10 € http://www.digikey.fr/product-detail/fr ... ND/2119686
* everything else ...

200 € does not seem not high for what is put in the bench.

Around such components, companies like Textronix or Keysight build high-end instruments worth thousand of euros.
In comparison, the Red Pitaya is lacking on a few points :
1) analog interface (it could have been much better with a few more euros and careful design)
2) calibration
3) user experience
If you think of the Red Pitaya as an oscilloscope, it can be deceptive.

However, if you consider it as programmable instrument, the possibilities are endless.
The Red Pitaya is an amazing platform to build instruments!
In my case, playing with the Red Pitaya has also been a fantastic learning experience.

The 6 points you raised are software issues that can be fixed.
The guys from Red Pitaya recently made lots of efforts in improving the usability.
Maybe the open source community can also help.

Personally, I would like the efforts to be more focused on the programmability of the device...
There is still a unique FPGA design in the official repository https://github.com/RedPitaya/RedPitaya
I don’t find any place with tutorials that teach how to do things from the start level
The only ressource that I could think of is the work of Pavel Demin (although a bit rough at the start level) :
* blog : http://pavel-demin.github.io/red-pitaya-notes/.
* code : https://github.com/pavel-demin/red-pitaya-notes

Best,
Jean

Howardlong
Posts: 18
Joined: Fri Feb 19, 2016 6:26 pm

Re: Expectations with RP

Post by Howardlong » Tue Mar 01, 2016 8:04 pm

I really can't recommend the RP as a beginner device in any way after my experiences of the past ten days. The scope app doesn't work, and neither does the visual programming. The specrum analyser works. The developer instructions on the wiki which you're guided to through the website are woefully out of date and wrong. Frequently I found the examples just don't work.

The RP is for hard core tinkerers with plenty of time on their hands. Claims that it's a bench instrument as it stands I find to be rather overstated.

With regret, a far, far better instrument for beginners looking for an oscilloscope and signal generator is the Digilent Analog Discovery. In fact, I used an Analog Discovery to debug some code on the RP at the weekend while I was travelling. The software is far more mature and it doesn't need an internet connection to work.

The outlook for developers and OEMs is better on the RedPitaya if they have enough patience.

It'll be interesting to see Peter Oakes' second video on the RP (the first came out today). I wonder if he'll have better luck than me?

pavel
Posts: 520
Joined: Sat May 23, 2015 5:22 pm

Re: Expectations with RP

Post by pavel » Tue Mar 01, 2016 9:04 pm

Howardlong wrote:With regret, a far, far better instrument for beginners looking for an oscilloscope and signal generator is the Digilent Analog Discovery.
The reference manual of the new Analog Discovery 2 instrument is impressive. Even though the complete schematics is not available, the most important analog parts are well documented:
https://reference.digilentinc.com/analo ... :refmanual

It would be really nice to have something similar for Red Pitaya.

Howardlong
Posts: 18
Joined: Fri Feb 19, 2016 6:26 pm

Re: Expectations with RP

Post by Howardlong » Wed Mar 02, 2016 11:40 am

There is an API available for the AD but I've not used it. I doubt it's any use as an SDR which would demand continuous sampling, but I may be wrong.

The AD also is a USB device rather than LAN attached. The benefit is that it means the AD's bus powered so doesn't require its own power supply, but equally you're limited to having the device in close proximity to your host PC which may or may not be a constraint.

What is nice about the AD is that you can run several instruments simultaneously, and that's a frequent use case. It also includes a reasonably useful logic analyser with bus decoding and a digital signal generator which can occasionally be useful. But by far the best thing about the AD when used as a bench instrument is the software.

The difference between the original AD and the AD2 is that the AD2 has a variable voltage +/- power supply unlike the AD which has a fixed voltage +/- 3.3V supply. Other than that they are identical in specification. The original documentation specified the bandwidth of the scope at about 5MHz, but this was at about 0.1dB down. In practice, and when using the BNC adapter board, the 3dB bandwidth is about 30MHz on both the AD and AD2. Sampling rate for the scope, waveform generator, LA and digital signal generator is 100MHz which is somewhat limiting for medium and high speed applications, but certainly by no means useless.

I used my AD at the weekend while travelling to debug some code on the RP, making for a powerful mixed signal development environment.

waqasjunaid
Posts: 1
Joined: Tue May 22, 2018 5:59 pm

Re: Expectations with RP

Post by waqasjunaid » Tue May 22, 2018 6:03 pm

handbook of software reliability engineering Software Life Cycle, Software Testing, Safe Introduction of Software Using Scale Up, Informal Proofs, Wrapping, Numerical Reliability, and Tools for Software Reliability.
Go to computersciencepdf dot com and than go to the handbook of software reliability engineering.

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