Blogs

libsigrok has gained a long-overdue feature recently: support for so-called probe groups.

Until now, various config options for drivers have always applied to all probes of a device. For example, on a 2-channel oscilloscope like the Rigol DS1052E you could set e.g. the "Volts per division" config option to a certain value (say, 2V). However, the setting would always be applied to all probes (i.e., both channels of the scope). It was not possible to set different values for each individual probe.

The new probe groups feature (via the respective API changes in the drivers and libsigrok backend code) allows each driver to define groups of probes that have the same properties and the same settings. This applies to all kinds of drivers/devices (not just oscilloscopes), including multimeters, logic analyzers, MSOs, thermometers, and so on.

The following example sigrok-cli call will change the V/div setting on a Rigol DS1052E scope to 2V, but only on the "CH1" probe group (which happens to only contain one probe, the first channel of the scope):

 $ sigrok-cli --driver rigol-ds1xx2:conn=/dev/usbtmc0 --probe-group CH1 -c vdiv=2V --set

It does not change the V/div setting of all other probe groups (i.e., the second channel of the scope in this case).

Thanks a lot to Martin Ling for coming up with the proposal for probe group support in libsigrok, as well as the initial implementation!

So far the rigol-ds1xx2 driver has been converted to actively use the new probe groups feature. Various other drivers will follow over time.
 

Hi everyone!

We're happy to announce the release of libsigrok 0.2.2! This is a minor bugfix release without any API changes, but it also adds support for a few new devices.

We added support for one new logic analyzer in this release, the Saleae Logic16. This is a streaming 16-channel device with a max. samplerate of 100MHz (when 3 channels are used; lower samplerates must be used if you use more channels). The driver was contributed by Marcus Comstedt, thanks a lot! You can use the sigrok-fwextract-saleae-logic16 tool from our sigrok-util repository to extract the required bitstream and firmware files from the vendor software.

We now also support a few more multimeters (all of them with RS232 connectivity):

• ISOTECH IDM103N, a Cyrustek ES51978 based 4000 counts DMM (thanks Aurelien Jacobs)
• Norma DM950 (a.k.a Normameter 950 a.k.a. Siemens B1028), a 21000 counts DMM (thanks Matthias Heidbrink)
• Metex M-4650CR (a.k.a. Voltcraft M-4650CR)

And two new thermometers (temperature dataloggers):

• UNI-T UT325, a 2-channel temperature logger with USB connectivity
• Center 309 (a.k.a. Voltcraft K204), a 4-channel temperature logger with RS232 connectivity

Finally, the first "device" in the "Energy meters" category that we support: the EDF Teleinfo (thanks Aurelien Jacobs!). This is not a specific piece of gear per se, but rather a standard protocol that is used for energy metering purposes in France.

Apart from the expanded device support, there is also the new csv input module (file format), thanks Marc Schink! That means you can now read logic analyzer data from various CSV-like files into libsigrok (and then do everything with that data you can do normally, e.g. convert to other formats, display, run protocol decoders on it and so on).

There have also been a number of improvements and fixes for various drivers (e.g. uni-t-dmm, ols, rigol-ds1xx2, agilent-dmm) and some random bugfixes and portability fixes in the rest of the code. Feel free to browse the NEWS file or git log for the details.

You can download the libsigrok-0.2.2.tar.gz tarball from sigrok.org/download as usual.

Have fun!
 

We're happy to announce that libsigrok now supports yet another multimeter, the Norma DM950 (a.k.a. Normameter 950, a.k.a. Siemens B1028).

This is a 21000 counts autorange DMM with RS232 connectivity.

Many thanks to Matthias Heidbrink for writing the driver and figuring out the protocol! As always we have a nice wiki page for this device now, including teardown photos, protocol description, and so on.

The DMM uses a custom microcontroller internally, and the protocol is a SCPI-like ASCII based protocol with the familiar-looking "IDN?" strings and so on. Please also check the driver source code if you're interested in the details.

There are various other DMM models from this series which can be supported relatively easily via this driver. Please contact us (and/or the driver author, "mh") in the #sigrok IRC channel on Freenode if you own one of these devices and can test further patches. Thanks!

libsigrokdecode now supports a new protocol decoder (PD) named parallel.

This PD can decode various simple synchronous, parallel buses that have one clock line and a (pretty much) arbitrary number of data lines.

The decoder can be configured to sample the data lines (e.g. D0-D3 for a 4-bit sync parallel bus, D0-D7 for an 8-bit bus, or D0-D31 for a 32-bit bus, and so on) on either the rising or falling clock edge.

It can then print the data in various formats (currently only 'hex' is supported, but more can be added easily), e.g. 0x55 for an 8-bit bus or 0x55667788 for a 32-bit bus, and so on.
 

The first conference presentation on sigrok is long overdue, but it's finally happening: Matt Ranostay is giving a talk at ELCE in Edinburgh, October 24-25. He will be giving an overview of the current state of the project. Thanks, Matt!

Quite a few sigrok developers will be at ELCE, and so we're also going to have a technical showcase stand, where we hope to demonstrate, among other things, PulseView's new integration with libsigrokdecode. If you're around, do drop by and say hello!

We'll also have a developer meetup, of course. We always have lots of designs in the planning stages, and getting together really helps to hash out the details. If you want to learn more about the internals of sigrok, or just have a say on where you want things to go, you're welcome to join us.

So today I have another example of the powerful ways sigrok-cli can be used, this time with digital audio.

In the modern world there are a wide variety of devices that handle digital audio internally including HiFi equipment and mobile phones. Common signalling schemes include S/PDIF, and various clocked serial PCM schemes. I²S is a specific variant of PCM signalling. It has 3 signals: Clock, Word Select (which signals the beginning of sample words for the left or right channels), and Data which transmits the audio samples MSB first.

sigrok has had support for I²S decoding for a while, and now in the latest Git builds of PulseView, it's possible to see the decode results. This example was taken from the 32-bit I²S example in the sigrok-dumps repository.

But once again thanks to the power of UNIX, sigrok-cli is the far more powerful tool, because it allows us to do interesting things with the decoded information.

The basic syntax for I²S decoding is as follows:

$ sigrok-cli -i 2ch-16bit-16khz.sr -P i2s:sck=0:ws=1:sd=2 -A i2s=right

i2s: "Right channel: f6780000" "Right: f6780000" "R: f6780000" "R"
i2s: "Right channel: f4b80000" "Right: f4b80000" "R: f4b80000" "R"
i2s: "Right channel: f3ac0000" "Right: f3ac0000" "R: f3ac0000" "R"
i2s: "Right channel: f3060000" "Right: f3060000" "R: f3060000" "R"
    ....

Here 32-bit samples are being printed for the right channel only. In itself this is very cool, but we can go much further.

The next step is to extract the data as binary.

sigrok-cli -i 2ch-16bit-16khz.sr -P i2s:sck=0:ws=1:sd=2 -A i2s=right | \
    cut -c22-25 | xxd -r -p > file.bin

The cut command strips all the text except for the 4 most significant hexadecimal nibbles, and in the same way as in the previous blog posting, we use xxd's reverse mode to convert this hexadecimal data to binary.

We now have a binary dump of the PCM data for the channel.

But I want more.

The SoX suite has some really handy tools for manipulating audio, and we can use these tools to convert the audio to a WAV file.

sigrok-cli -i 2ch-16bit-16khz.sr -P i2s:sck=0:ws=1:sd=2 -A i2s=right | \
    cut -c22-25 | xxd -r -p | \
    sox -t raw -B -b 16 -c 1 -e signed-integer -r 16k - right.wav

Here we tell sox that it will receive a raw data stream, containing big endian, 16-bit, signed integer mono audio at 16kHz sample rate, and that it should output the data to a wav file.

Opening the wav file in Audacity, we can see the decoded analog waveform:

...or we can use the sox play tool to play the audio directly out of the headphones:

sigrok-cli -i 2ch-16bit-16khz.sr -P i2s:sck=0:ws=1:sd=2 -A i2s=right | \
    cut -c22-25 | xxd -r -p | \
    play -t raw -B -b 16 -c 1 -e signed-integer -r 16k -

I've never had the chance to try it, but I really want to see if it's possible to do this in real time on a live device.

At this time, it will be a tall order to ask this of libsigrokdecode, but it may nonetheless be possible. It would require a logic analyser capable of continuous streaming, such as the FX2 family of devices, and the I²S logic data would need to be acquired at the lowest possible sample rate without aliasing. If the logic data is captured at a higher sample rate, libsigrokdecode stands no chance of processing all of it.

There is some talk of various ways we can make great increases to libsigrokdecode's performance, so in the future this type of realtime activity should be rather easier to do.

Thanks to Aurelien Jacobs libsigrok now supports a new multimeter, the ISO-TECH IDM103N. This is a 4000 counts DMM with RS232 connectivity.

The respective patch for enabling this DMM also adds a generic es519xx.c parser (based on the old es51922.c which will be obsoleted soon), which should be able to handle various Cyrustek ES519xx DMM ICs. That'll make it easy to add more DMMs using one of these Cyrustek chips later.

Another new thing in libsigrok is the SR_UNIT_REVOLUTIONS_PER_MINUTE (RPM) unit, which allows us to properly support the DMM's RPM feature.
 

We're happy to announce that libsigrok now supports the Saleae Logic16 logic analyzer.

This is the successor product of the well-known Saleae Logic (an 8-channel logic analyzer with a max. samplerate of 24MHz and streaming capabilities).

The Logic16 has 16 channels and can sample at rates of up to 100MHz, depending on the number of channels used. If you only need 3 channels you can sample at 100MHz, or 50MHz for 6 channels, or 32MHz for 9 channels, or 16MHz when using all 16 channels.

The property of the Logic16 that makes it really interesting is that it can still stream out the data live over USB (like the Logic) and is thus not limited to any internal buffer size of the logic analyzer itself, while at the same time allowing a samplerate higher than 24MHz. This makes it possible to capture fast signals for longer periods of time (as opposed to just a few milliseconds as is the case for many other devices) which can be very useful in practice.

It also has the advantage that you can switch between two different voltage threshold settings, allowing you to debug either 1.8V / 3.3V systems, or 5V systems.

Of course it still has the same limitations as the Logic, too. Whether the continuous byte stream from the Logic16 can be received quickly enough over USB without missing any bytes depends on various random factors, such as the USB controller in your PC, the OS/kernel version used, the amount of other USB devices connected and how much data those transfer at the same time, etc. etc. But still, for many cases it works well enough to make it quite useful.

Many thanks to Marcus Comstedt for figuring out how the Logic16 protocol works, and for writing the libsigrok driver! He also documented the protocol in the wiki, as well as various firmware internals. We also have some teardown photos, pinouts of the ICs used in the Logic16 and their connections, EEPROM layout and other info in the wiki, if you're interested in this kind of stuff.

The device uses a Cypress FX2 USB chip and a Xilinx Spartan-3A XC3S200A FPGA internally. The first needs a firmware upload when the Logic16 is attached to USB, the latter needs an FPGA bitstream upload upon USB connection (as well as another bitstream upload whenever the voltage threshold setting is changed).

Thanks to Marcus Comstedt again who provided the sigrok-fwextract-saleae-logic16 tool which you can use to extract the FX2 firmware and the two FPGA bitstreams from the vendor software. See the manpage for details.
 

The collectd project is the de facto standard setup for server statistics: it grabs all kinds of local statistics (network counters, disk I/O, etc) and logs it locally or to a remote collectd, say on a dedicated statistics machine. It's a very modular system: everything is in plugins, including input sources like SNMP and OneWire. The default output plugin is the venerable RRDtool. This stores values and averages them over time, and creates graphs on demand.

Collectd has just released version 5.4, now with a sigrok plugin. That means any device which can be accessed via libsigrok can feed information to collectd, for storage and graphing with RRDtool or any other output plugin. This is intended for the many analog devices supported in libsigrok, not the oscilloscopes and logic analyzers of course.

These graphs were made using a CEM DT-8852 sound level meter and UNI-T UT325 thermometer:

These show my clunky old air conditioning unit adding a whopping 19 dB(A) to the noise level, and the effect that has on the temperature. I also watched a very loud movie with lots of explosions in the evening! Here's the collectd configuration that generated the above:

LoadPlugin "sigrok"
<Plugin "sigrok">
    LogLevel 3
    <Device "Sound level">
        Driver "cem-dt-885x"
        conn "/dev/ttyUSB3"
        MinimumInterval 1
    </Device>
    <Device "Temperature">
        Driver "uni-t-ut32x"
        conn "1a86.e008"
        MinimumInterval 1
    </Device>
</Plugin>