[Discuss-gnuradio] Make USRP run w/o SW intervention

[Reginald Cornwallice]

Hello Friends,

My name is Reginald and I am an SDR enthusiast currently pursuing my latest project with the N210 box. I have the utmost respect for this hardware and hope to integrate it into my newest intellectual pursuit.

My project is a box that sends and receives cellular SMS messages and with my expertise being mostly in FPGA I am tackling this venture by modifying the FPGA code. So far I have been successful implanting my HDL based cellular receiver in the FPGA after the dsp_core_rx module and a attaching my transmit directly to the DAC output pins, bypassing dsp_core_tx.

However, it seems that the box cannot run standalone without software intervention because the ethernet IO is not free running and ADC and DAC clocks can be shut off by software. Furthermore, it seems running example programs such as rx_samples_to_file overwrite SPI values programmed to AD9510 in the firmware burned onto the motherboard,  for example, changing the divisors for the clocks to ADC and DAC. I confirmed this by probing the hardware.

My project works when I run rx_samples_to_file program to force the board to be active on receive and transmit, and also force the ethernet output to be active, which I have configured to send out some status messages so I can tell the demodulator is functioning.

Is there any simple change I can make to the FPGA or firmware in order to have the box run without intervention, meaning all the SPI programming is handled by firmware, DAC/ADC clocks are on forever, and the ethernet output is continuously putting out the output I've wired it up for in the FPGA?

Many thanks for any assistance on this matter.


Reginald