Transmission starts immediately even though a start_time is provided when using MultiUSRP.send_waveform() in the Python bindings

[zolveuran]

Issue Description

Transmission starts immediately even though a start_time is provided when using MultiUSRP.send_waveform() in the Python bindings. Caused by metadata.has_time_spec not being set to True when metadata.time_spec is set.

Suspect the same issue is present for recv_num_samps, where stream_cmd.stream_now = False is missing when stream_cmd.time_spec = start_time.

Setup Details

• USRP 2954
• Python bindings built on Ubuntu 22.04 (WSL2) on latest master (#d18647dd)
• FW version: 6.0
• FPGA version: 39.0
• FPGA git hash c781f75

Expected Behavior

Providing start_time should delay the start of transmission until the specified time.

Actual Behaviour

Transmission starts immediately.

Steps to reproduce the problem

Build UHD with Python bindings. Run tx_waveforms.py but modify to add start time.

Additional Information

Verified that my solution works for send_waveform. I'm not able to confirm recv_num_samps at the moment as I currently don't have physical access to the hardware.

[mbr0wn]

Fixed by f3815f3