Hi there!
We are setting up an AD9081 with the Stingray X-band radar front end. We can get the radar to control it's T/R timing with the TDD module, but are having a hard time synchronizing the data capture to get coherent capture of each radar pulse. If we continuously sample the buffer across T and R, we can enable the TX in continuous mode, and then just sample many pulses of data continuously. That seems to essentially start at a random point in the pulse, but we can then reshape it to be coherent across pulses until it gets to 2^16 samples, at which point it jumps to a new reference position in the pulse. We assume it's filling up a buffer and then dumping it before beginning sampling again.
If we try using the sync_start features, and run the example script (https://github.com/analogdevicesinc/pyadi-iio/blob/master/examples/ad9081_sync_start_example.py), the device never modes into the "arm" state. We tried using the iio_attr and iio_info commands to directly control the device, but it still does not respond there, remaining in "disarm" mode, but indicating that "arm" and "trigger_manual" states are available (see data at bottom of post). We looked at the HDL to make sure that the EXT_SYNC is enabled, which we believe it is. We checked the box in the ADI AXI DMA Controller (axi_mxfe_rx_dma) for "Transfer start synchronization" enable. But we can't seem to move the 9081 to "arm" to get it through the sequence.
Any help in identifying what is required to capture the A/D data starting at the same time each pulse (soon after the end of the pulse) to get coherent returns with known range (time) offset would be appreciated.
root@analog:~# iio_attr -d axi-ad9081-rx-hpc .
dev 'axi-ad9081-rx-hpc', attr 'adc_clk_powerdown', value :'0'
dev 'axi-ad9081-rx-hpc', attr 'filter_fir_config', value :ERROR: Permission denied (13)
dev 'axi-ad9081-rx-hpc', attr 'jesd204_fsm_ctrl', value :'1'
dev 'axi-ad9081-rx-hpc', attr 'jesd204_fsm_error', value :'0'
dev 'axi-ad9081-rx-hpc', attr 'jesd204_fsm_paused', value :'0'
dev 'axi-ad9081-rx-hpc', attr 'jesd204_fsm_resume', value :ERROR: Permission denied (13)
dev 'axi-ad9081-rx-hpc', attr 'jesd204_fsm_state', value :'opt_post_running_stage'
dev 'axi-ad9081-rx-hpc', attr 'loopback_mode', value :'0'
dev 'axi-ad9081-rx-hpc', attr 'loopback_mode_available', value :'0 1 2 3'
dev 'axi-ad9081-rx-hpc', attr 'multichip_sync', value :'0'
dev 'axi-ad9081-rx-hpc', attr 'powerdown', value :'0'
dev 'axi-ad9081-rx-hpc', attr 'sync_start_enable', value :'disarm'
dev 'axi-ad9081-rx-hpc', attr 'sync_start_enable_available', value :'arm disarm trigger_manual'
dev 'axi-ad9081-rx-hpc', attr 'waiting_for_supplier', value :'0'
