AD9371 OBS as an extra RX channel

Are you using Linux or no os drivers? Can you share your init script? Hope you are enabling the ORX channel while initializing the chip?

Using analogdevicesinc/linux with the PetaLinux build system.  

Init:

$BIN_DIR/profile_loader.py -i $PROFILE_DIR/profile_rx100_ob200.txt > $LOG_DIR/profile_loader.log 2>&1

sleep 1

# Configure AD9371 gain control to manual
iio_attr -c ad9371-phy voltage0 gain_control_mode manual
iio_attr -c ad9371-phy voltage2 gain_control_mode manual

# Disable Tx1 and Tx2
iio_attr -D ad9371-phy adi,tx-settings-tx-channels-enable 0

# Set OBS pll: OBSLO_SNIFFER_PLL (1) OBSLO_TX_PLL (0)
iio_attr -D ad9371-phy adi,obs-settings-obs-rx-lo-source 1

# Configure AD9371 obs source
iio_attr -D ad9371-phy adi,obs-settings-default-obs-rx-channel 5
iio_attr -c ad9371-phy voltage2 rf_port_select ORX1_SN_LO

We are able to work around it by using the following calls from the ad9381-iiostream example:

get_ad9371_stream_ch(ctx, OBS, obs, 0, 'i', &obs_i)
get_ad9371_stream_ch(ctx, OBS, obs, 0, 'q', &obs_q)
iio_channel_enable(obs_i);
iio_channel_enable(obs_q);
obsbuf = iio_device_create_buffer(obs, 1024*1024, false);

Using analogdevicesinc/linux with the PetaLinux build system.  

Init:

$BIN_DIR/profile_loader.py -i $PROFILE_DIR/profile_rx100_ob200.txt > $LOG_DIR/profile_loader.log 2>&1

sleep 1

# Configure AD9371 gain control to manual
iio_attr -c ad9371-phy voltage0 gain_control_mode manual
iio_attr -c ad9371-phy voltage2 gain_control_mode manual

# Disable Tx1 and Tx2
iio_attr -D ad9371-phy adi,tx-settings-tx-channels-enable 0

# Set OBS pll: OBSLO_SNIFFER_PLL (1) OBSLO_TX_PLL (0)
iio_attr -D ad9371-phy adi,obs-settings-obs-rx-lo-source 1

# Configure AD9371 obs source
iio_attr -D ad9371-phy adi,obs-settings-default-obs-rx-channel 5
iio_attr -c ad9371-phy voltage2 rf_port_select ORX1_SN_LO

We are able to work around it by using the following calls from the ad9381-iiostream example:

get_ad9371_stream_ch(ctx, OBS, obs, 0, 'i', &obs_i)
get_ad9371_stream_ch(ctx, OBS, obs, 0, 'q', &obs_q)
iio_channel_enable(obs_i);
iio_channel_enable(obs_q);
obsbuf = iio_device_create_buffer(obs, 1024*1024, false);

My guess is that you mentioned enabling the channels during initialization, which we accomplished with:

iio_channel_enable(obs_i);
iio_channel_enable(obs_q);

obsbuf = iio_device_create_buffer(obs, 1024*1024, false);

The odd part is that the RX channels didn't require these same calls.

Moving to the Linux subspace.

Hi,

You should always enable and disable the channels required.

Not doing it and depending on some defaults can lead to undesired behavior.

So please consider this not a workaround, but mandatory operations.

The main RX is handled here:

https://github.com/analogdevicesinc/linux/blob/master/drivers/iio/adc/ad9371_conv.c#L185

This code enables the channel by default.

While the ORX is handled by a completely different driver, which doesn't do that.

-Michael