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Uwe Hermann's blog

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


New protocol decoder: Aosong AM230x / DHT11

We're happy to announce that libsigrokdecode now supports the am230x protocol decoder.

This PD decodes the custom protocol of the Aosong AM230x and DHT11 temperature and humidity sensors.

A short description of the protocol is available on the respective wiki page, along with pointers to further reading.

There are also a bunch of teardown photos of these sensors, in case you were wondering what those look like inside. Turns out they usually use some ST STM8S (or other) microcontroller and measure temperature and humidity "directly" without further ICs. The exception being the Aosong AM2303 which actually uses a Dallas/Maxim DS18B20 (1-Wire) sensor for the measurement.

Thanks a lot to Johannes Roemer for contributing the decoder!

sigrok at the Chaos Communication Congress (31C3)

As in previous years various sigrok developers will be at the Chaos Communication Congress (31C3) in Hamburg, Germany. The conference takes place December 27th to 30th, 2014.

There will be a sigrok assembly (on all 4 days) with a few tables and chairs to allow for sigrok hacking and development planning, various demos and Q&A for visitors, and so on.

Apart from sigrok hacking the conference also features the usual set of awesome talks related to security, hardware hacking, and lots of other interesting topics that you shouldn't miss.

If you're interested in sigrok as user or developer, please drop by and say hello. Bring your gear (if possible) for reverse engineering and driver writing purposes. Chat with us, give us your suggestions which features you'd like to see, which devices you want to be supported, which protocol decoders you'd like to have, or even help us write some drivers/decoders!


New protocol decoder: rfm12

libsigrokdecode now supports yet another protocol decoder, rfm12.

This one decodes the SPI-based protocol of the HopeRF RFM12 and RFM12B wireless FSK transceiver modules. These devices can transmit and receive in the 433MHz, 868MHz and 915MHz bands (depending on chip).

Thanks a lot to Sławek Piotrowski for contributing the decoder (as well as an example file for sigrok-dumps)! We've also added a small test-case in the sigrok-test repository to be able to keep track of any potential regressions that might occur later.

Manson HCS-3xxx series programmable power supply support

We're happy to announce that libsigrok now supports the Manson HCS-3xxx series of programmable power supplies (PPS).

Thanks a lot to Matthias Heidbrink for improving the driver and extending it to support more models in this series! See the model overview for more details. There are various rebadged versions sold by Conrad/Voltcraft, PeakTech, and probably other resellers.

All power supplies in this series have one channel only, featuring various voltage/current/power combinations though. They're connected to the PC via a (built-in) USB-to-serial IC (e.g. the SiLabs CP2102 in the Manson HCS-3202). A relatively simple ASCII-based protocol is used to communicate with the devices and control them.

You can control the power supplies e.g. via sigrok-cli like this:

 $ sigrok-cli -d manson-hcs-3xxx:conn=/dev/ttyUSB0 --show
 manson-hcs-3xxx - Manson HCS-3202 with 1 channel: CH1
 Supported configuration options:
    output_current: 0.000000
    output_current_limit: 0.000000
    output_enabled: on (current), off
    output_voltage: 3.390000
    output_voltage_target: 0.000000

 $ sigrok-cli -d manson-hcs-3xxx:conn=/dev/ttyUSB0 --samples 2 -O analog
 CH1: 3.300000 V DC
 CH1: 0.000000 A
 CH1: 3.380000 V DC
 CH1: 0.000000 A

 $ sigrok-cli -d manson-hcs-3xxx:conn=/dev/ttyUSB0 --config output_voltage_target=5.0 --set

 $ sigrok-cli -d manson-hcs-3xxx:conn=/dev/ttyUSB0 --config output_enabled=yes --set

The code was tested on the Manson HCS-3202 and the Voltcraft PPS-11815. Please let us know if you are able to test any of the other devices the driver is supposed to support, and/or whether you experience any issues.


New protocol decoder: spdif

libsigrokdecode now supports the spdif decoder.

The Sony/Philips Digital Interface Format (S/PDIF) is a (nowadays standardized in IEC 60958) digital audio protocol that is used in various devices and supported by a number of ICs, such as the TI PCM2707 and many others.

A short description of the protocol is available on the respective wiki page, along with pointers to further reading.

Thanks a lot to Guenther Wenninger for contributing the decoder!


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