Glad to see you’re still around BenF. May we please have some simple IIR low, high, and bandpass/stop filters for the scope in the latest firmware?
I have found a bug in the latest firmware (v3.64).
My DSO nano V1 gets stuck every time that I try to enter the “ME” mode with “DSO BenF Firmware v3.64”.
I have downgraded it to “DSO BenF Firmware v3.62” and now it works fine.
Mine gets stuck too en ME or FI menu when it have the SD card inserted, any one can send to me the v3.62? jjpl2001@email.com
It would be more helpfull if you post a link to the SD card (type, brand, size) you’re having problems with.
BenF, care to comment on the possibility of simple IIR filters for the DSO Nano?
en.wikipedia.org/wiki/Infinite_impulse_response
en.wikipedia.org/wiki/Low-pass_filter
The current firmware version supports two FIR filters, namely peak and average. These are used in fast (oversampled) mode for display rendering (raw capture data used for export is not filtered). I also implemented a version of the sinc filter (see Nyquist sampling theorem and Whittaker-Shannon) which is a popular low pass IIR filter. The brute force implementation added about 75s (one minute and 15 seconds) per buffer cycle. A highly optimized version of this filter may approach 1/10 of that, but at 7.5s per cycle (which may be unrealistic) it is still not useful for practical purposes.
Most IIR filters will likely require processing beyond the capability of the Nano M3 Cortex as what we currently have is already a stretch at the maximum rate of 1MS/s. Another issue is that every single byte of RAM is used for the existing feature set and so adding new functionality is not possible unless some feature is also removed. One popular request has been for FFT (Fast Fourier Transforms) and at moderate (audio) frequencies, this is achievable, but not in combination with a rich general purpose feature set as we have now.
Those interested in filter/sampling theory can use the Nano capture capability, transfer the files to a PC and post-process the data using tools like Matlab.
Thanks for the detailed response!
I have a few comments, if that’s ok.
Thanks! I wondered how those were implemented, and both modes are quite useful. The new peak mode has already proven helpful at quickly identifying high-frequency signals (especially when added to low-frequency signals), and average seems to produce a smoother output than ever.
I agree. However, while I’m not a mathematician, I think the sinc filter may be overkill.
en.wikipedia.org/wiki/Low-pass_filter
Simply weighting the current value with the previous one seems relatively cheap, and very similar to RC filters. A fourth order low pass filter is more than enough for typical audio and biosignal applications. An eighth order filter provides extreme attenuation. For high pass filtering, a single order is often enough. Deep bandpass/stop functionality seems possible with the same IIR filter design.
The properties of most unwanted signals lend themselves to such simple processing quite well. 60Hz noise is the most common annoyance, and it should be easily eliminated with a single-order notch filter. Selecting tones from a noisy environment (eg. amateur radio, power line communication, EMG detection), can be done with a single order bandpass filter. High frequency switching noise (>1khz) can be thoroughly suppressed with relatively low-order low-pass filters. For very low frequency signals (eg. biosignal baseline wandering, infrasonic audio, etc), a single order high pass filter can provide arbitrary cutoff frequencies with strong attenuation of the unwanted signals.
Simple notch filters should be trivial and are are especially important. Implementing a 60Hz notch filter in hardware is virtually impossible. Even using a UAF42 chip (precision thomas-biquad filter) with purpose-ordered precision resistors, 60Hz attenuation is limited to about 5-7x.
A drop in sampling rate while using filters is completely acceptable. 100KS/s should be plenty, far less may be acceptable for many applications.
Switching firmware on the fly is rather easy, especially since user settings seem to persist. I would elect to drop SD card support, calibration, cursors, and perhaps some measurements (duty, pcnt, pwdt) for specialized firmware versions. Also, while I did hear there are no plans to develop your latest firmware as open-source, does that exclude a GCC port?
I tried the FFT firmware, and if it worked well, I might have been happier. However, FFT plots are often noisy and hard to read; that one was no exception. Frankly, filters or waterfall plots are far more useful. Filters are usually best, since the resulting waveform is useful in its own right.
The nano has quite limited capture capability, making this a really slow process. Far, far, far too slow for lab use.
Hi Ben, hi all,
Is it possible to put the box with the measurements on the bottom or to divide the box and put one part on the bottom, and the other part on the top? I want to view my signal together with the measurements, but that box blockes half the part of the signal.
Just started using V3.64 with a DSO Nano V1. I decided to try the FIT mode, with 440 Hz sine wave input. When I increased the signal level requiring a vertical range change, I found a band of input levels throughout which the scope will continually switch back and forth between the two ranges. Have you observed this behaviour?
Thanks for update. but I have a problem in 3.64.
I use 2GB SD card and change mode to the ME or FI ,then freeze the system.
It work when no card or 8GB SDHC insert.
I try two different card and it isn’t broken because I can use this cards another system.
Do you have any idea?
When can I download the latest source?
Just wanted to say thanks to Benf. Outstanding work on the firmware. I really appreciate it.
Thanks also to Lygra for the excellent youtube tutorials.
Now I just need to return my Quad which is basically useless.
Thanks BenF, What a major improvement to my DSO201! Its obvious you have allot of time and effort into this, and clearly GOD blessed you with impressive software talents as well. I sure appreciate it and highly recommend this upgrade to anyone nervous about losing their original firmware. You wont regret this upgrade, makes the nano much more like a quality conventional scope.
Thanks again BenF, I sure appreciate your efforts.
Is the trouble described in the following topic, known by BenF firware 3.64 user ? Thanks.
Regards.
The post linked to above suggests the problem is the same with the stock firmware. If it is indeed a problem that can be fixed in firmware, why is there no fix available and why was it shipped defective in the first place?
The display problem is news to me and keep in mind that V2 has been in the market now longer than its predecessor. It could be unique to a batch of units or a result of HW modifications in a late production run. As buyers, I don’t think you should settle for “please understand …”, but rather demand a fix or replacement.
Hi BenF and all users of this forum, excuse my english, i’m not native english speaker
I am new to this forum and to the DSO nano v2.
I installed BenF firmware 3.64
If you ever plan to make an upgrade, I want to point to a feature that is missing, in the frequency generator menu maybe you can add a “burst” function, that can be preset (5, 10, 50, 100 pulses) or can be user defined
you can set frequency
you can set
if you can set a number of pulses to be generated, then the a automotive tool used to verify injector balance become useless, all you need is to make a driver for the injector so it will use the battery power and use the nano to command that driver, the driver can be made with one FET, or any switch transistor able to handle the load.
Also i noticed that the generator is always on, is that consuming resurses?
Anyway thank you very much for your effort into making this firmware.
Hello Decebel76,
I am not involved with the firmware myself, just a fellow Nano owner. I just wanted to say your english is pretty good,
honestly its not obvious english is not your native language in writing form anyways! I do think however you may have meant to say “if you can[size=150]t[/size] set a number of pulses to be generated, then [size=150]as[/size] a automotive tool used to verify injector balance [size=150]it[/size] become useless,…” ? Seems to make more sense that way, amazing how one “T” can invert the whole meaning of a sentence! Curious project you are envisioning, Using the nano to operate a fuel injector, I was thinking injectors were actuated with a more digital signal of one “on state” per injection of a varying length, rather than an “inverting variable frequency burst” per injection, Perhaps you have a product idea there, if that is added,you could produce a device ready to connect to the vehicle battery , injector terminals(maybe even a kit with various adapters) a hook for the Nano output and a place to put the ground clip and you have a pretty handy injector verifier. you could even include a regulator to power the nano through the usb port from the vehicle power. Then again maybe I am totally confused what you are trying to do and how it allow you to see a imbalance in the injectors.
I am pretty sure you are correct the frequency generator is consuming power all the time, even if there no output current just inverting the voltage against the micro-tiny capacitance of the output circuit has to be pulling some current.
Battery life can be limiting so that is a good suggestion too! Anyways, I hope that was helpful, Troy
thank you for reply
i meant that the nano gives the command to the injector and the injector is using the car battery
between nano and the injector is used a transistor, that is the injector driver
the nano and the injector driver share the ground
here is an example
the imbalance can be seen by measuring the pressure drop in the fuel line with a pressure gauge, you measure the pressure drop for each injector starting from the same pressure and giving to each injector same command(same number of pulses, same frequency, same duty)
From where do i get the video tutorials of this DSO firmware version 3.64 as i have acquiring interest in this topic and i also want to know that is there any tutorial guides also available so that it would be much easier to learn.