Completely disabling bluetooth.

[Anne]

Hey!

I'm working on a device which requires Bluetooth to be completely disabled for short periods of time. It's got a sensor in it that's sensitive to 2.4 GHz radiation. Chip is nRF51822, SoftDevice is S110 v6.0.0.

I disable Bluetooth using the following code snippet:

	// If connected, disconnect
	if (m_conn_handle != BLE_CONN_HANDLE_INVALID)
	{
		err_code = sd_ble_gap_disconnect(m_conn_handle,  BLE_HCI_REMOTE_USER_TERMINATED_CONNECTION);
		if (err_code != NRF_SUCCESS) return err_code;
	}

	// Stop advertising
	err_code = sd_ble_gap_adv_stop();
	if (err_code != NRF_SUCCESS) return err_code;

And reenable later by calling advertising start.

Does disconnecting and stopping advertising completely shut down the radio or do I need to do something more low-level? I want to be as certain as possible that Bluetooth isn't interfering with the sensor.

Cheers,

Anne.

[scytulip]

Hi, Anne,

I investigated the code for BLE serialization and found no clue of turning off Bluetooth completely.

However, I tried another solution:

NRF_RADIO->TASKS_DISABLE = 1;

It works! See the Fig.23 in NRF51822 reference manual v2.1, it says "No operations are going on inside the radio and the power consumption is at a minimum." I think this is what you need.

I tried this code,

advertising_start();
nrf_delay_ms(2000);

NRF_RADIO->TASKS_DISABLE = 1;

nrf_delay_ms(2000);
advertising_start();

Then the BLE resumes advertising without any problem.

[Anne]

I'm using the application timer module. I'm not sure, but I think disabling and reenabling the SD would mess them up. I've also got a critical region which uses sd_critical_region_enter which is called when Bluetooth needs to be active as well as when it needs to be disabled. I could manage these, of course, but it would be nice to know if there's any alternative.

[John]

I think the application timers would be unaffected by disabling and enabling the SD. They rely on SWI0 and RTC1 and those are "open" even when the SD is enabled. I do not know if the critical regions would still work with the SD disabled.

[Anne]

Thanks for your input guys ^^ I'll most definitely try out your suggestions and will let you know how they work :)

[Anne]

I finally got a chance to test it and it works fine for me too ^^