Switching from BLE mode to nRF/generic 2.4GHz mode not working properly?

[rbmarcus]

I am using nRF5 SDK v15.0.0 and an nRF52840 with the S140 SoftDevice (6.0.0). I have an application that works using a custom protocol with the nRF radio. Recently I added BLE functionality and switching to it works flawlessly, but when I attempt to disable the SoftDevice and switch back to the original wireless protocol, the radio doesn't work anymore. Specifically, the RADIO_IRQHandler is never called. Below I included most of the functions I use. Basically I start by enabling the radio, confirming it receives data, then I enable and disable BLE mode (which should re-enable the radio without the BLE stack).

void nrf_mode_init(void)
{
    NRF_RADIO->FREQUENCY = 0;
    NRF_RADIO->TXPOWER = (RADIO_TXPOWER_TXPOWER_Pos8dBm << RADIO_TXPOWER_TXPOWER_Pos);
    // I have a custom function here, setting PCNF0, PCNF1, CRCCNF, CRCINIT, CRCPOLY, MODE, INTENSET, and SHORTS
}

void nrf_mode_reset(void)
{
    NVIC_DisableIRQ(RADIO_IRQn);
    NRF_RADIO->EVENTS_DISABLED = 0U;
	NRF_RADIO->TASKS_DISABLE = 1;
    NRF_RADIO->EVENTS_END = 0U;
	NRF_RADIO->TXPOWER = (RADIO_TXPOWER_TXPOWER_Pos8dBm << RADIO_TXPOWER_TXPOWER_Pos);
}

void nrf_mode_enable_rx(void)
{
	NRF_RADIO->PACKETPTR = (uint32_t) &rx_packet;
	NVIC_ClearPendingIRQ(RADIO_IRQn);
	NVIC_EnableIRQ(RADIO_IRQn);
	NRF_RADIO->TASKS_RXEN = 1;
}

void ble_mode_init(void)
{
    nrf_mode_reset();
    ble_stack_init();
    gap_params_init();
    gatt_init();
    services_init();
    advertising_init();
    conn_params_init();
    advertising_start();
}

void ble_mode_disable(void)
{
    uint32_t err_code = nrf_sdh_disable_request();
    while(nrf_sdh_is_enabled()); // placeholder, confirmed SD is disabled in primary code before enabling nrf mode
    nrf_mode_init();
    nrf_mode_reset();
    nrf_mode_enable_rx();
}

Is there anything else I should be doing to fully disable the SoftDevice and to allow the RF mode to work properly?

[hmolesworth]

The SD takes over the interrupt vectors, though it might forward them when the SD is disabled which presumably is the case priot to enabling the SD. Maybe try power-cycling just the Radio:

NRF_RADIO->POWER = 0; /* Turn the radio off */
wait a bit ..
NRF_RADIO->POWER = 1; /* Turn the radio on */

[rbmarcus]

Thanks! I tested this out with nrf_delay_ms(5) in between and unfortunately it didn't work, but it's good to know that the SD takes over interrupt vectors. That may be related to the problem I'm having.

[Kenneth]

Can you take a look at the following example:
https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/ble_sdk_app_gzll.html 

I can for instance find the following implemention is used to switch from BLE->proprietary radio usage:

void ble_stack_stop(void)
{
    uint32_t err_code;

    err_code = nrf_sdh_disable_request();
    APP_ERROR_CHECK(err_code);

    ASSERT(!nrf_sdh_is_enabled());
}

Kenneth

[rbmarcus]

This is the example I used as a reference. Once nrf_sdh_is_enabled() returns 0, I continue testing the custom radio behavior. My program does not crash, but it also no longer triggers the RADIO_IRQHandler after entering and exiting BLE mode.

[Kenneth]

I can see that now, but I can't see anywhere you are starting the HFCLK?

Kenneth

[Kenneth]

One more thing, in addition to starting the HFCLK, let the first step after disabling the softdevice be to power cycle the radio peripheral using the POWER register:
https://infocenter.nordicsemi.com/topic/ps_nrf52840/radio.html#register.POWER

Kenneth

[rbmarcus]

Thank you for your response Kenneth. I managed to fix the problem, which was a combination of internal library initializations that needed to be called again, and notably this clock init function:

static void clock_initialization()
{
	/* Start 16 MHz crystal oscillator */
	NRF_CLOCK->EVENTS_HFCLKSTARTED = 0;
	NRF_CLOCK->TASKS_HFCLKSTART = 1;

	/* Wait for the external oscillator to start up */
	while (NRF_CLOCK->EVENTS_HFCLKSTARTED == 0)
	{
		// Do nothing.
	}

	// Old CLOCK_LFCLKSRC_SRC_Xtal -> Start long ? Rev C ?
	/* Start low frequency crystal oscillator for app_timer(used by bsp)*/
	NRF_CLOCK->LFCLKSRC = (CLOCK_LFCLKSRC_SRC_RC << CLOCK_LFCLKSRC_SRC_Pos);
	NRF_CLOCK->EVENTS_LFCLKSTARTED = 0;
	NRF_CLOCK->TASKS_LFCLKSTART = 1;

	while (NRF_CLOCK->EVENTS_LFCLKSTARTED == 0)
	{
		// Do nothing.
	}
}

I assume this solved the problem by restarting the HFCLK as you mentioned, and because of your response I was able to track this function down. I'm sorry for continually asking questions related to the deprecated nRF5 SDK, but I seriously appreciate all the help these forums and the Nordic dev team have provided, and we plan to switch to NCS + Zephyr for future products.