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--- resources:tools-software:linux-software:libiio:iio_readdev [23 May 2019 02:51]
Travis Collins Update to modern IIO tools
+++ resources:tools-software:linux-software:libiio:iio_readdev [30 May 2019 02:35]
Travis Collins Update example to use realistic rates and DDS frequency
@@ Line 50: / Line 50: @@
 dev 'ad9361-phy', debug attr 'loopback', value :'1'
 </xterm>
-  - set the DDS to something slow, so it is easier to see, and we don't alias when looking at things in the time domain.<xterm>analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage0 frequency 5000**
+  - set the DDS to something slow, so it is easier to see, and we don't alias when looking at things in the time domain.<xterm>analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage0 frequency 50000**
 Using auto-detected IIO context at URI "usb:2.26.5"
 dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage0' (output), id 'TX1_I_F1', attr 'frequency', value '9279985'
 wrote 5 bytes to frequency
-dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage0' (output), id 'TX1_I_F1', attr 'frequency', value '5156'
+dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage0' (output), id 'TX1_I_F1', attr 'frequency', value '50034'
-analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage1 frequency 5000**
+analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage2 frequency 50000**
 Using auto-detected IIO context at URI "usb:2.26.5"
-dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage1' (output), id 'TX1_I_F2', attr 'frequency', value '9279985'
+dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage2' (output), id 'TX1_I_F2', attr 'frequency', value '9279985'
 wrote 5 bytes to frequency
-dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage1' (output), id 'TX1_I_F2', attr 'frequency', value '5156'
+dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage2' (output), id 'TX1_I_F2', attr 'frequency', value '50034'
 </xterm>
@@ Line 69: / Line 69: @@
 dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage0' (output), id 'TX1_I_F1', attr 'scale', value '0.400024'
-analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage1 scale 0.4**
+analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage1 scale 0.0**
 Using auto-detected IIO context at URI "usb:2.26.5"
 dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage1' (output), id 'TX1_I_F2', attr 'scale', value '0.000000'
 wrote 4 bytes to scale
-dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage1' (output), id 'TX1_I_F2', attr 'scale', value '0.400024'
+dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage1' (output), id 'TX1_I_F2', attr 'scale', value '0.000000'
 analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage2 scale 0.4**
@@ Line 81: / Line 81: @@
 dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage2' (output), id 'TX1_I_F2', attr 'scale', value '0.400024'
-analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage3 scale 0.4**
+analog@imhotep:~$ **iio_attr -a -c cf-ad9361-dds-core-lpc altvoltage3 scale 0.0**
 Using auto-detected IIO context at URI "usb:2.26.5"
 dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage3' (output), id 'TX1_I_F2', attr 'scale', value '0.000000'
 wrote 4 bytes to scale
-dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage3' (output), id 'TX1_I_F2', attr 'scale', value '0.400024'
+dev 'cf-ad9361-dds-core-lpc', channel 'altvoltage3' (output), id 'TX1_I_F2', attr 'scale', value '0.000000'
+</xterm>
+  - Set the sample rate to something reasonable for the DDS frequency<xterm>
+analog@imhotep:~$ **iio_attr -a -i -c ad9361-phy voltage0 sampling_frequency 3000000**
+Using auto-detected IIO context at URI "usb:2.29.5"
+dev 'ad9361-phy', channel 'voltage0' (input), attr 'sampling_frequency', value '3000000'
+wrote 8 bytes to sampling_frequency
+dev 'ad9361-phy', channel 'voltage0' (input), attr 'sampling_frequency', value '3000000'
 </xterm>
   - capture 1024 samples in 256 sample buffers <xterm>analog@imhotep:~$ **iio_readdev -u usb:3.80.5 -b 256 -s 1024 cf-ad9361-lpc > samples.dat**
@@ Line 100: / Line 107: @@
 0000080   01431   00225   01401   00370   01356   00512   01296   00648
 </xterm>
-  - plot the results in gnuplot:<xterm>analog@imhotep:~$ .**gnuplot**
+  - plot the results in gnuplot:<xterm>analog@imhotep:~$ **gnuplot**
 gnuplot> **plot 'samples.dat' binary format='%short%short' using 1 with lines, 'samples.dat' binary format='%short%short' using 2 with lines**
-</xterm>{{:resources:tools-software:linux-software:libiio:readdev_gnuplot.png?600|}}
+</xterm>{{ :resources:tools-software:linux-software:libiio:sine_wave_pluto.png?600 |}}
-  - you can see from the discontinuities that the sample rate is too high, so check that.<xterm>analog@imhotep:~$ **iio_attr -a -i -c ad9361-phy voltage0 sampling_frequency**
+  - If you can see discontinuities then the sample rate is too high, so check that.<xterm>analog@imhotep:~$ **iio_attr -a -i -c ad9361-phy voltage0 sampling_frequency**
 dev 'ad9361-phy', channel 'voltage0' (input), attr 'sampling_frequency', value '30720000'
 </xterm>You can expect that 30.72 MSPS is too fast to stream over USB with zero gaps between buffers. Increasing the buffer length is the best thing to do.

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