DDS Mode: set scale(dBFS) is not working under mac os x on an Adalm Pluto board and no tone is output by the board

[sacatak]

When I set on my mac machine the parameter scale(dBFS) in DDS Mode for "one cw tone" or "two cw tones", I can't see any tone outputs from the board. When I do the same configuration from my ubuntu machine, it works. Both machines have the same version: master-g8825ea7 and libiio-version:0.18-c0012d0 I have found a workaround under mac by using debug>cf-ad9361-dds-core-lpc and writing directly the iio device attributes like output atlvoltage0(TX1-I_F1) scale to outputs the tone. I have the feeling that setting the scale of the tones by the DDS mode window do nothing. In addition when I push "reload settings", I see that these scale values are always refresh with -inf value since I put a value directly in the iio device attributes

[tfcollins]

I can't repeat this issue on Mojave with master or the latest release. The version of macOS are you on? Have you tried the brew builds?

-Travis

[sacatak]

Thanks Travis for your return. My mojave version is 10.14.6. I'm not too familiar with brew. I've installled the software with the following command: brew install --HEAD tfcollins/homebrew-formulae/i-i-o-oscilloscope. As it seems that it was probably a software issue, I've edit the brew with "brew edit tfcollins/formulae/i-i-o-oscilloscope" to test the branch "2019_R1" by adding: ,:branch => "2019_R1" at the end of line head "https://github.com/analogdevicesinc/iio-oscilloscope.git". And I have the same behavior with the 2019_R1 version. I don't understand what you mean by trying the brew builds. Concerning the libad9361, I've installed the latest: master_latest_libad9361-iio-darwin-10.14.4.pkg Do you have other ideas to investigate.

Regards, Nicolas

[tfcollins]

Try the Mac instructions here: https://wiki.analog.com/sdrseminars

-Travis

[sacatak]

Dear Travis,

I've followed the instructions from https://wiki.analog.com/sdrseminars on an other mac computer and I've still have the problem. Regards, Nicolas

[sacatak]

Oct-25-2019 22-33-44.mp4.zip

Dear Travis, I use the adalm pluto with a loopback between TX and RX. In this video, I have set the RX OL to 2400Mhz and the TX OL to 2400.5Mhz. I want to output a tone at 5Mhz in TX base band and it should appears at 2405.5Mhz on the spectrum. At the begin of the video all these parameters are set except the scale of the tone (equal to -inf)and I try to change the scale of the tone and nothing happens. When I push reload settings the scale came back to -inf. After that I put directly the value on the register for I and Q and the spectrum shows the tone. The video is cut but when I do a reload on the scale, it takes the value expected and not the -inf value Regards, Nicolas

[mhennerich]

What LOCALE settings are you using?

[tfcollins]

@mhennerich is probably right here. We've seen similar things with non-English installs

-Travis

[sacatak]

What LOCALE settings are you using?

Thanks @mhennerich for your your answer. My locale settings are french. I have installed english locales, restart and now it works! Thanks to both of you. I'm wondering if this bug was not du to the translation of dB in linear that should give a float. In French locale, we use the dot instead of comma. Maybe there is issue around this

Regards, Nicolas

[sacatak]

Dear @tfcollins , Do you think is it possible to correct this behaviour? Regards, Nicolas

[tfcollins]

This can be difficult for us to support since no current staff use that locale. We do accept full requests if you find a solution:). I will defer to @mhennerich though.

-Travis

[mhennerich]

The problem is really that the kernel has a fixed API. For IIO the scales use a period to indicate the decimal place. It is a very common problem, but libiio is intended to work around it by providing methods such as iio_device_attr_read_double() to mitigate this problem. (see libiio/utilities.c) The issue persists if for exmple iio_device_attr_read() is used and then the string maybe containing a number is parsed using scanf() and friends. There seems to be such places dac_data_manager and and it's underlying iio_widget library.

Maybe @dNechita can have a look and see if there is a simple fix.

-Michael

[dNechita]

It's very likely that parts of iio-osc are interpreting float strings in a way which ignores LOCALE. I'll look into it. But in this case I can track the problem all the way to libiio, were iio_device_attr_write_double() doesn't work as expected. The internal implementation of iio_device_attr_write_double() will use iio_snprintf() which is actually snprintf. This happens because on macOS the following never gets defined: https://github.com/analogdevicesinc/libiio/blob/v0.18/utilities.c#L33 Therefore, the snprintf will format a string using a comma instead of dot which is specific to a number of locales. E.g "0,44". When this string if passed to iio_channel_attr_write(), it fails with Invalid Argument as error.

[dNechita]

A few more details about this: Simple programs based on libiio (e.g iio_info, iio_readdev, etc.) work well on mac OSX because they get a default locale (which is called locale C) no matter what locale is set on the system. What happens for iio-oscilloscope is that it is also based on GTK2 which is a UI library that needs to be aware of locale. In iio-oscilloscope, when gtk_init() gets called, internally, the locale is being set to whatever the system locale is. From this point on everything is being affected by locale, including libiio.