How to prevent Radio test from stopping with cli disconnected?

[cpeng]

Hi Devzone:

We put the radio test project on our custom battery powered board and encountered a problem.

When we disconnect the usb cable, the tone emitted by radio test project disappeared.

We want to disconnect the cable as the cable could act as an antenna.

Why the radio test needs usb cable connected to keep running? Where can I modify the code so that disconnecting cable would not stop the test?

Thanks.

[cpeng]

Hi Jared, sorry I wasn't very specif in describing what I did:

by turning off all asserts, I just commented out ASSERT lines in nrf_cli_uart.c, nrf_cli.c, nrf_queue.c

I guess it's probably not beneficial to do.

The board is powered by battery, so after USB cable disconnected the code still runs.

I did have the board swd pins still connected after I disconnect the usb cable, and fired up the debugger.

Do you have any recommendation of what to check? The debugger shows the code still runs, bouncing between some nrf_cli files.

[Jared]

Hi,

The example uses CLI which again is dependent on the USB peripheral if you chose USB as the transport layer. CLI is used for communicating with the user on how to setup the test. You would have to modify the entire example so that it isn't dependent on the USB as transport layer. I haven't tested this but you could try to use the UART  as transport layer instead.

regards

Jared 

[cpeng]

Hi Jared:

Thanks for keep tracking this problem. Now with a new try the problem changes a little bit.

I spliced radio_test project with cli project in SDK 17.0.2 instead of 16, everything works with usb plugged in. CLI commands output a tone which I can measure in a spectrum analyzer. 

Now with USB cable unplugged, the tone didn't go away. Instead it shifts down by an offset.

For example, if cli command sets up a tone at channel 80 which is 2.48G, unplugging USB would have the tone shift down to 2.435Ghz. Similar offsets happens with other channels too.

Do you have any suggestion what could cause this shift?

Thanks again.

[Jared]

Hi,

SDK 17.0 includes a fix in the handling of the USB CLI backend when a port is closed. The changed behavior is probably related to this. I have a suspicion that your new behavior is caused by the example stopping the HFXO when you unplug the USB cable. Could you either probe the crystal or read out the NRF_CLOCK->HFCLKSTAT and see if it's stopped when you unplug the cable?

regards

Jared 

[cpeng]

Hi Jared: I will try to see if the clock stops and get back to you.

Oh and I need to clear out a confusion: in order to use radio project over USB, I had to merge the radio_test project with cli project so the CLI is through USB, not UART.

I think in the future Nordic should build a radio test project that does CLI over USB instead of UART.

Because UART needs the ARM chip on the DK board to work, and most people use radio test project on their own customized board in order to test their radio performance, and most likely the board will not have a huge ARM chip on it, so it defeats the purpose of building radio test project over UART.