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New protocol decoder: Jitter

libsigrokdecode has had support for the jitter protocol decoder for a while now (it is already shipped with the recently-released libsigrokdecode 0.3.1), but this hasn't been officially announced yet, so here goes.

The decoder allows you to retrieve the timing jitter between two digital signals. This can be useful for a number of things, e.g. finding jitter/delay between a sender and receiver (be it wired or over some form of wireless communication), or for debugging your firmware interrupt setup by checking how much jitter you have between multiple consecutive invocations of the interrupt handler that should in theory always be equally spaced.

We also added a small test-case in our sigrok-test repository so we can ensure that the PD works fine (and continues to do so upon changes).

This protocol decoder has been contributed by Sebastien Bourdelin, thanks a lot!

libsigrokdecode 0.3.1 released!

We're happy to announce that libsigrokdecode 0.3.1 has been released.

You can download the libsigrokdecode-0.3.1.tar.gz source tarball from as usual.

This is mostly a bugfix-release, the C library API was not changed. This means existing frontends that work with / are linked against libsigrokdecode 0.3.0 will continue to work just fine, without requiring relinking or recompiling.

However, some of the protocol decoders' output changed in ways which are not compatible with the state of the decoders in the last libsigrokdecode release. This means, if you're using any scripts to parse decoder output, or if you have any "private" protocol decoders that stack on top of one of those shipped with libsigrokdecode, you will have to do some adaptations. You're also encouraged to submit such decoders to be included in libsigrokdecode proper, of course!

In addition to all kinds of improvements and bugfixes in existing protocol decoders (PDs), you're probably most interested in what new protocol decoders are now supported (backported from git HEAD). So here's the list:

  • adns5020: Bidirectional command and data over an SPI-like protocol
  • am230x: Aosong AM230x/DHTxx/RHTxx humidity & temperature sensor
  • arm_etmv3: Decode ETM instruction trace packets
  • arm_itm: Trace data from Cortex-M / ARMv7m ITM module
  • arm_tpiu: Filter TPIU formatted trace data into separate streams
  • eeprom24xx: 24xx series I²C EEPROM protocol
  • jitter: Retrieves the timing jitter between two digital signals
  • mdio: Half-duplex sync serial bus for MII management between MAC and PHY
  • mrf24j40: IEEE 802.15.4 2.4 GHz RF tranceiver chip
  • nrf24l01: 2.4GHz transceiver chip
  • pwm: Analog level encoded in duty cycle percentage
  • rfm12: HopeRF RFM12 wireless transceiver control protocol
  • spdif: Serial bus for connecting digital audio devices
  • stepper_motor: Absolute position and movement speed from step/dir
  • swd: Two-wire protocol for debug access to ARM CPUs
  • tca6408a: Texas Instruments TCA6408A 8-bit I²C I/O expander
  • timing: Calculate time between edges

This adds up to currently 54 supported PDs in total.

Please check the libsigrokdecode NEWS file for the full list of user-visible changes in this release. As always, we're happy about bug reports, feature suggestions, comments about which protocol decoders you'd want supported next, or even better — patches :)

Happy decoding!

Maynuo M9812 now supported

We're happy to announce that libsigrok now supports the Maynuo M9812 digital load.

The driver was contributed by Aurelien Jacobs, thanks a lot!

It was written in a pretty generic way so that it probably also supports many of the other devices in the Maynuo M97 series of devices.

If you are able to test one of the other devices in that list, please let us know!

The hardware is attached via a (virtual) serial port and communication happens via a protocol on top of Modbus RTU (as documented in the user's guide)

There are also a bunch of teardown photos (plus links to the relevant ICs and their datasheets) of the device on the wiki page, if you're interested in that kind of stuff.

New protocol decoder: Avago ADNS-5020

We're happy to announce that libsigrokdecode now supports the adns5020 PD, a decoder for the Avago ADNS-5020 optical mouse sensor protocol.

The decoder was contributed by Karl Palsson, thanks a lot!

It stacks on top of the common SPI PD and decodes ADNS-5020 specific registers reads and writes.

There is an example file in the sigrok-dumps repository if you want to test the decoder, as well as a test config in our sigrok-test repository.


New protocol decoder: 24xx I²C EEPROM

It's been a while since the eeprom24xx protocol decoder was added to libsigrokdecode, but there hasn't been an "official" announce yet, so here goes.

The eeprom24xx PD can decode the I²C-based protocol of (almost) all 24xx series EEPROMs from various vendors.

Supported chips include for example the Microchip 24LC64 or 24AA025UID, the ST M24C01 or M24C02, the Siemens SLx24C01 or SLx24C02, and others. Various other chip families can be added relatively easily via chip spec entries in the decoder's file.

These ICs usually have only very few bytes of storage (e.g. 128 or 256 bytes), where the memory is organized into pages (the page size is e.g. 8 or 16 bytes). They usually support various types of accesses (command sequences) such as "byte write", "page write", "current address read", "random read", "sequential random read", "sequential current address read", and others.

Apart from a common command subset, some of the chips also support custom non-standard commands such as "set write protection" or "read write protection status" (on ICs that have write-protectable areas), and some others.

UNI-T UT372 now supported

libsigrok now supports a new device class, tachometers! The first supported device of this type is the UNI-T UT372.

It's a USB-attached device (uses one of the WCH CH9325 ICs commonly found in UNI-T gear) that can measure RPM and counts.

The protocol of the device (now documented in the sigrok wiki) was reverse engineered by Mike Walters, using a somewhat unusual and quite interesting technique. Instead of the usual method of sniffing the USB traffic and then staring at hex numbers until things start to make sense, he used the following method:

After a first quick look at the USB traffic it was pretty clear that the packets usually look something like this:


Now, instead of trying to figure out which bit and byte means what by looking at many of these packets, Mike instead generated his own packets that looked like the real packets from the UT372. He sent them to the vendor's PC software (via a custom-built "emulator" on a USB-enabled Arduino), which then interpreted and displayed the values and flags that it thought were sent by an actual UT372 device.

By randomly flipping bits in these packets and observing how the PC software's interpretation of the packets differed, Mike was able to figure out the individual protocol details a lot faster than using other methods.

Shortly after the protocol was known, Martin Ling wrote a libsigrok driver for the UT372 by hooking up a device-specific ut372 parser to the existing uni-t-dmm driver in libsigrok (which already handles the somewhat "special" CH9325 details).

Thanks a lot to Mike Walters and Martin Ling for their contributions!


BayLibre ACME now supported

libsigrok now supports the BayLibre ACME device.

This a BeagleBone Black cape with an I²C-attached Texas Instruments INA226 current/power monitor and an I²C-attached TI TMP435 temperature sensor.

The sensors are supported in mainline Linux. The drivers expose a standard interface via the Linux sysfs pseudo file system, which the libsigrok driver uses.

The driver was contributed by Bartosz Golaszewski (of BayLibre), thanks a lot!

Bartosz will also present a Sigrok: Adventures in Integrating a Power-Measurement Device talk at the Embedded Linux Conference on March 24, 2015 (schedule) in San Jose, CA.


New protocol decoders: ARM TPIU, ITM, ETMv3

We're happy to announce that libsigrokdecode now supports three new, closely related, protocol decoders: arm_tpiu, arm_itm, and arm_etmv3.

Here's a quick overview of the protocols that are decoded:

  • The TPIU (Trace Port Interface Unit) is a stream formatter and multiplexer that combines data from several sources into one stream. It is used inside an ARM-based microcontroller or SoC to combine ITM and ETM trace output into a single port.
  • ARM ITM (Instrumentation Trace Macroblock) allows tracing of software events, and also with the help of DWT (Debug, Watchpoint and Trace) the tracing of exceptions and data watchpoints. It also supports periodic sampling of PC values.
  • ARM ETM (Embedded Trace Macroblock) allows tracing of every instruction executed on the CPU. Currently only ETM version 3 (the newest version, present in Cortex-M3 and other ARMv7-m) is supported.

The data is captured on the SWO (TRACESWO) pin, e.g. on commonly available ARM SWD (serial wire debug) programmers/debuggers. Hint: libsigrokdecode also ships with an SWD decoder, if you're interested in that...

You can test the decoders with some sample files from the sigrok-dumps repository. If you optionally supply the location of ARM (cross-)toolchain utilities such as arm-none-eabi-objdump or arm-none-eabi-addr2line you can decode even more information, including source code snippets (see screenshot below)!

That opens up a whole new bunch of debugging possibilities; you can basically debug your code by not only tracing instructions but also tracing them in relation to other signals you're capturing with your logic analyzer at the same time (e.g. GPIOs you're toggling, UART, SPI, I²C, or whatever else may be going on in the system you're debugging)!

All three decoders were contributed by Petteri Aimonen (including sample *.sr files and a small test-suite for our sigrok-test repository), thanks a lot!

Happy debugging!


MASTECH MS8250B supported

libsigrok now supports yet another multimeter, the MASTECH MS8250B.

This is a 4000 counts autorange DMM with USB connectivity (via an internal USB-to-serial IC built into the DMM).

Apart from the usual measurement ranges it also features a nice non-contact voltage detector functionality.

Thanks to Baruch Even for contributing and testing the code for this DMM (which is now part of the serial-dmm driver via a relatively small patch)!


New protocol decoder: PWM

We're happy to announce that libsigrokdecode now supports the pwm protocol decoder.

The PD was contributed by Torsten Duwe and Sebastien Bourdelin, thanks a lot!

This decoder will show the duty cycle of any signal, which in practice can mean various things. E.g. Class-D amplifiers can use PWM to encode audio data.

We have a test file in the sigrok-dumps repository containing audio data.

The decoder also supports a binary output facility which you can use to decode the audio (a direct export to WAV is planned as well, though).

 $ sigrok-cli -i -P pwm:data=4 -B pwm=raw > PWM.raw
 $ sox -t raw -e unsigned -b 8 -r 64000 PWM.raw PWM.wav
 $ aplay PWM.wav



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