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ad9361 spi32766.0 error for RX on FMCOMMS5

Question asked by brandonj on Feb 6, 2015
Latest reply on Feb 9, 2015 by mhennerich

I have some application software that requires 4 channel receive and I'm having difficulty getting it to work. I'm using libiio and in my C code I'm enabling all 8 (4 IQ) channels of the FMCOMMS5. I pulled the latest, 2014_R2 a few days ago from libiio, hdl, kernel, and rootfs.

 

As a test I generate a CW from a siggen at a LO offset and connect it to channel 4. When I reboot and run osc on the target I observe the CW at the proper offset on the proper channel. However, as soon as I run my C application which attempts to capture all 4 channels the data appears to repeat samples 2x, so I observe a CW at offset/2 in addition to an alias.

 

I observed the scan_elements/enable files and they look correct, but one odd thing I noticed was that the ad9361 driver spit out an error when I ran my software. Here's a rundown of the procedure with some observations along the way:

 

<reboot. display contents of RX enable voltages>

root@analog:~# cat /sys/bus/iio/devices/iio\:device6/scan_elements/in_voltage*_en

1

1

1

1

1

1

1

1

 

<osc, enable channel 4 (voltage6,7)>

root@analog:~# cat /sys/bus/iio/devices/iio\:device6/scan_elements/in_voltage*_en

0

0

0

0

0

0

1

1

 

<run my software via network context. capture and plot data. observe CW at offset/2 + alias in frequency domain>

 

ad9361 spi32766.0: Rx0 is not enabled

 

root@analog:~# cat /sys/bus/iio/devices/iio\:device6/scan_elements/in_voltage*_en

1

1

1

1

1

1

1

1

 

<switch to osc app. enable osc on channel 4 and capture>

 

root@analog:~# cat /sys/bus/iio/devices/iio\:device6/scan_elements/in_voltage*_en

0

0

0

0

0

0

1

1

 

<in osc, observe CW at offset/2 + alias in frequency domain>

 

I traced this error to ad9361.c, line 1013 in the kernel drivers. It looks like it's a result of the SPI read failing on the register REG_RX_ENABLE_FILTER_CTRL (0x003). Any ideas of what I'm doing wrong? I've tested this application with the FMCOMMS3 and I don't have this issue.

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