SDR-Widget Digitization Unit

The SDR-Widget is a device that enables the digitization of low-frequency signals from SDR receivers and the control of their components (local oscillator, filter bank, and antenna switches) via the I2C bus. From the operating system's perspective, the device can behave like a standard sound card or send data through the SDR-specific GHPSDR protocol. This is an open-source project, but the hardware is now difficult to obtain despite its usefulness.

The entire device can also be built from MLAB kit modules. Specifically, it uses the AT32TQ14401A module equipped with the MCU AT32UC3A3256. This is connected to the adcaudio module, which digitizes the signal. Other modules, like the display, buttons, or I²C devices, can be connected as needed.

Download the tool package and header files from the Atmel website, for example:

• Atmel AVR 32-bit Toolchain 3.4.2 - Linux 64-bit
• Atmel AVR 8-bit and 32-bit Toolchain (3.4.2) 6.1.3.1475 - Header Files

Unpack the toolchain into the directory ~/avr32-tools. Then, place the AVR32 header files from the second package into this directory at $HOME/avr32-tools/avr32/include.

Alternatively, you can skip this step and download a preserved version of the AVR32 toolchain from MLAB Downloads.

wget http://home.mlab.cz/Downloads/Software/AVR32/avr32-tools_3.4.2.tar.bz2  ~/Download/

Then continue with the following steps:

cd ~/Download
tar -xvzf avr32-tools_3.4.2.tar.bz2
mv avr32-tools_3.4.2 $HOME/avr32-tools
export PATH=$PATH:$HOME/avr32-tools/bin

Test the functionality and version of the toolchain with:

kaklik@popelnice:~/programy/sdr-widget$ avr32-gcc --version
avr32-gcc (AVR_32_bit_GNU_Toolchain_3.4.2_435) 4.4.7
Copyright (C) 2010 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

If the output is similar to the above, you can proceed with compiling the SDR-Widget.

git clone  https://github.com/borgestrand/sdr-widget
cd sdr-widget/
git checkout audio-widget-experimental

Then compile the source code using the following command:

make sdr-widget

The result of the compilation will be utility programs and firmware, which will be uploaded to the MCU using the program-widget script via the dfu-programmer utility. See below.

To upload the firmware, we need a modified dfu-programmer, which we download as follows:

sudo apt-get install autotools-dev aclocal  
git clone https://github.com/MLAB-project/dfu-programmer-sdr-widget.git
cd dfu-programmer-sdr-widget/
./bootstrap.sh
./configure
make
sudo make install

You can download an older compiled version of the firmware from Google Code. However, for MLAB applications, an updated version with some bug fixes is used:

wget https://github.com/MLAB-project/sdr-widget/releases/download/bolidozor-v01/widget.elf

Before running the upload script, press the BOOT button (unlabeled button, hold it down until the RESET button is pressed and released) and the RESET button on the AVR32TQ board.

 sudo ./program-widget widget.elf

For any modifications, first run:

make clean

Then you can start the compilation again.

For the basic SDR-Widget construction, two modules are needed:

• adcaudio
• at32tq144

They are interconnected as follows:

Red, Blue

AT32TQ14401A/POWER +5V → ADCaudio01B/POWER +5V

Yellow 10cm

ADCaudio01B/MCLK → AT32TQ14401A/PC04

ADCaudio01B/BCLK → AT32TQ14401A/PX28 → AT32TQ14401A/PX34

ADCaudio01B/DOUT → AT32TQ14401A/PX25

ADCaudio01B/LRCLK → AT32TQ14401A/PX26 → AT32TQ14401A/PX36

ADCaudio01B/OSR0 (near label) → AT32TQ14401A/PB00

ADCaudio01B/OSR1 (near label) → AT32TQ14401A/PB01

Jumper on AUDIOF0

AT32TQ14401A/JTAG2 → AT32TQ14401A/PB06

This section describes the connection when using the ADCaudio01A module clocked by the CLKGEN01B module. If using the newer ADCaudio01B module, which has an integrated oscillator, the connection simplifies for most applications. Connecting an external oscillator is useful if you need a very stable sampling frequency, for example, for scientific experiments.

Red, Blue

CLKGEN01B/Vcore 3.3V → ADCaudio01A/POWER +5V → AT32TQ14401A/POWER +5V

Orange, Black

CLKGEN01B/POWER → TTLPECL01A/POWER → PIC16F87x/POWER

SATA cable

CLKGEN01B/CLKOUT → TTLPECL01A/PECL0

Yellow

TTLPECL01A/TTL0 → ADCaudio01A/MCLK → AT32TQ14401A/PC04

Brown

USBI2C01A/SCL → CLKGEN01B/SCL

White

USBI2C01A/SDA → CLKGEN01B/SDA

Blue

USBI2C01A/I2C GND → CLKGEN01B/POWER GND

ADCaudio01A/BCLK → AT32TQ14401A/PX28 → AT32TQ14401A/PX34

ADCaudio01A/DOUT → AT32TQ14401A/PX25

ADCaudio01A/LRCLK → AT32TQ14401A/PX26 → AT32TQ14401A/PX36

ADCaudio01A/OSR0 (near label) → AT32TQ14401A/PB00

ADCaudio01A/OSR1 (near label) → AT32TQ14401A/PB01

Jumper on AUDIOF0

AT32TQ14401A/JTAG2 → AT32TQ14401A/PB06

The SDR-widget can be configured into several operating modes. The configuration is done using the WidgetControl.py utility. Before running it, install the necessary dependencies.

sudo apt-get install python-pythoncard python-usb

Run the configuration utility.

~/git/sdr-widget$ sudo ./WidgetControl.py

For standard use, such as inside a Bolidozor station, set the configuration as follows:

To apply the settings, disconnect and reconnect the SDR-widget to USB.

How to install AVR 32-bit Toolchain on Linux

• Audio Widget README

The easiest way to test the device is by connecting a signal generator to the input in the standard sound card mode. The generator's output should be connected to the balanced input of the ADC through a transformer. However, for this purpose, you can easily create one from a ferrite core taken from a switched PC power supply. A signal amplitude of a few millivolts is sufficient even with a 1:1 transformer.

The software used to display the signal from the generator can be, for example, PySDR, or you can directly use ghpsdr3.

The test can also be performed without a generator using noise observable at the ADC input. The easiest display can be achieved using GNU Radio, which can be installed as follows:

 sudo apt install gnuradio

Then download the test script.

 svn co svn://svn.mlab.cz/MLAB/Modules/Audio/ADCaudio01B/SW/sdr-widget_test.grc 

Open the test script in GNU Radio:

 gnuradio-companion sdr-widget_test.grc

After running the script by pressing “Play,” the displayed spectrum should look approximately as follows.

The SDR-widget digitization unit, thanks to its versatility, can be used in many measurement projects and detection networks.

• Bolidozor station rmds
• lightning
• Ionozor

• Solve the issue of timestamping samples.