Receiving on a set BLE frequency

[StevenG]

HI!

I'm currently working on a project where I'd like to send and receive BLE messages using my own channel hopping mechanism.

I've read into the 17.0.2 Examples > Peripheral > radio_test files for a first look at this but I'm having trouble actually making sure the things that I'm sending on a set frequency are able to be received.

As it seems easier to first do an unmodulated message, Id preferred doing this first

So far I have as peripheral/sender

/**
 * 
 * Function from radio_test.c example, line 306
*/

void radio_unmodulated_tx_carrier(uint16_t channel)
{
    radio_disable();

    //Radio modes constants: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/group__nrf__radio__hal.html#gacf631e29d43c93acac290a18850e9c40
    nrf_radio_mode_set(NRF_RADIO_MODE_BLE_1MBIT);
    //Using standard BLE 1MBit/sec

    //Radio tx powers constants: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/group__nrf__radio__hal.html#gaf10bff1d03d8156b3af56540701d6b3d
    nrf_radio_txpower_set(NRF_RADIO_TXPOWER_0DBM);

    //Set the frequency, in MHz
    nrf_radio_frequency_set(channel);

    //Task constants: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.0.2/group__nrf__radio__hal.html#ga607fff2f027c323b3dc8af40ab489a2f
    nrf_radio_task_trigger(NRF_RADIO_TASK_TXEN);
}

Which I derived from the mentioned example.

But now I'm having trouble receiving this. Also because I can't seem to find a good tutorial or something to explain this.

( https://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.sdk5.v15.2.0%2Fgroup__nrf__radio__hal.html is an empty reference guide?)

The current receiving function that I have is almost identical but changing the last task trigger to a 'TASK_RXEN' instead of 'TX'.

Any help or a good tutorial link :)?

Besides this I have some questions as well

1. This radio_disable() function, is this needed? It seems that if I boot up the board it should be disabled by default, why start by disabling this?

2. As of Bluetooth 5 we have bigger beacon packets. I assume this Radio HAL is only capable of using this 255byte message size right? The examples are using rather small payloads so I can't really tell.
Now that I'm typing this I'm not sure that this is even how this works, will look into this right after this post :)

3. Something totally unrelated, but I've spend too much time on this already so I figured I'd ask now.
I am still unable to turn on my LEDS in any way. I've flashed the basic turn-on-the-4-LEDS-examples, looked at the code, tried to replicate my own bsp_board_leds_on() functions, sdk_config should be fine? It's so basic that I gave up putting time into but it would be nice to toggle a led when an event occurs for example.

Currently the only LED blinking is the yellow power one.

Any tips?

Thanks in advance, 

Steven

[Kenneth]

Hi,

If you are interested in making a BLE enabled product you should use one of our precompiled softdevices:
https://infocenter.nordicsemi.com/topic/struct_nrf52/struct/nrf52_softdevices.html

E.g. nRF52840 + S140 softdevice, you should be able to find several examples in the nRF5 SDK (look for pca10056 (=nRF52840-DK) in \ble_peripheral folder).

The undertaking of trying to make a BLE enabled peripheral (or even Beacon) from scratch is simply to great.

Best regards,
Kenneth

[StevenG]

I think you misunderstood my question. 

I don't want to make something from scratch, I'd like to use the SDK to transmit/receive on frequencies that I calculate beforehand. Ive found examples on transmitting but not receiving.

And yes, I know this probably isn't super easy, I need to do this for my master thesis. I have to extend the MAC layer with my own.

[Kenneth]

The source you are looking at is not BLE in any way. I suggest to look at zephyr Bluetooth LE controller:
https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/guides/bluetooth/bluetooth-arch.html#source-tree-layout

The source should be available from:
https://github.com/zephyrproject-rtos/zephyr/tree/master/subsys/bluetooth/controller

In specific:
https://github.com/zephyrproject-rtos/zephyr/tree/master/subsys/bluetooth/controller/ll_sw/nordic

[StevenG]

Hey Kenneth, 

Thanks for the reply. I guess I was confused by the fact you could set the radio mode to a _BLE_ version?

I've done the Get Started tutorial, got the blinky working (yay) and now I was looking again at sending and receiving on a set frequency. 

In the API you provided I could find

void radio_freq_chan_set(uint32_t chan)

void radio_rx_enable(void)

void radio_tx_enable(void)

Which sounds promising!

But I'm unable to find any other information in the Docs about this. When I go into API Reference > Bluetooth > Controller, there is no mention of anything regarding the Github source.

Am I missing something? The source is quite new so it might just be that this is being worked on...

Thanks,

Steven

[Kenneth]

We don't have any more description than what you may find in the source and for the radio peripheral in the nRF52840 product specifications:
https://infocenter.nordicsemi.com/topic/ps_nrf52840/radio.html

The above should cover how to configure and use the radio. I assume you would need to refer to the Bluetooth core specification on what the configuration should be.

Kenneth