Connection between two hidden NRF51822 modules

[vldzero]

Hello

First of all, I would like to apologize if a similar question was already asked but all this BLE matter is so broad that it defeats me. I am planning to put two NRF51822 devices into my project. I want one of the devices to pull one of the GPIO pins down as soon as the other one is in the range of 10-30m. Also, I want it to be secure, I don't want anyone else to scan my devices, copy them and control the pin with another one. I want slave device to consume as low energy as possible.

My idea is:

1. make both devices undiscoverable so it will be difficult to scan for them.
2. The master device (the one that controls the GPIO pin) will advertise only to the slave one and it will be visible only for the slave one.
3. The slave device will check if it is in range of 10-30-m and if so it will send back a message/password or whatever to master. If it is not in range it won't send any message.
4. If master receives the message it pulls the pin down.
5. Repeat points 2-4 each 1s.

Is it possible to implement such routine? Or are there any better ideas? I am a total newbie in BLE. I managed to run simple advertising example but nothing more. I would appreciate a guidance, not a readymade solution.

vldzero

[Petter Myhre]

sd_ble_gap_whitelist_set() is not supported by S130.

The whitelist has be set when you start to advertise:

/**@brief GAP advertising parameters.*/
typedef struct
{
  uint8_t               type;                 /**< See @ref BLE_GAP_ADV_TYPES. */
  ble_gap_addr_t       *p_peer_addr;          /**< For @ref BLE_GAP_ADV_TYPE_ADV_DIRECT_IND mode only, known peer address. */
  uint8_t               fp;                   /**< Filter Policy, see @ref BLE_GAP_ADV_FILTER_POLICIES. */
  ble_gap_whitelist_t  *p_whitelist;          /**< Pointer to whitelist, NULL if no whitelist or the current active whitelist is to be used. */
  uint16_t              interval;             /**< Advertising interval between 0x0020 and 0x4000 in 0.625 ms units (20ms to 10.24s), see @ref BLE_GAP_ADV_INTERVALS.
                                                   - If type equals @ref BLE_GAP_ADV_TYPE_ADV_DIRECT_IND, this parameter must be set to 0 for high duty cycle directed advertising.
                                                   - If type equals @ref BLE_GAP_ADV_TYPE_ADV_DIRECT_IND, set @ref BLE_GAP_ADV_INTERVAL_MIN <= interval <= @ref BLE_GAP_ADV_INTERVAL_MAX for low duty cycle advertising.*/
  uint16_t              timeout;              /**< Advertising timeout between 0x0001 and 0x3FFF in seconds, 0x0000 disables timeout. See also @ref BLE_GAP_ADV_TIMEOUT_VALUES. If type equals @ref BLE_GAP_ADV_TYPE_ADV_DIRECT_IND, this parameter must be set to 0 for High duty cycle directed advertising. */
  ble_gap_adv_ch_mask_t channel_mask;         /**< Advertising channel mask. See @ref ble_gap_adv_ch_mask_t. */
} ble_gap_adv_params_t;

You can also let the advertising module handle it.

Add options.ble_adv_whitelist_enabled = true; in advertising_init().

Then you need to handle the BLE_ADV_EVT_WHITELIST_REQUEST event that you get in on_adv_evt(), by replying with ble_advertising_whitelist_reply().

[vldzero]

Still no success.....

I added below lines to the definition of advertising_start() function.

ble_gap_whitelist_t  whitelist;
	ble_gap_addr_t *p_whitelist_addr[1];
	ble_gap_addr_t  whitelist_addr = {BLE_GAP_ADDR_TYPE_RANDOM_STATIC,{0xfc, 0x45, 0x92, 0x76, 0xc4, 0x0c}} ; //MAC addres of my phone

and after memset(&adv_params, 0, sizeof(adv_params)); I added this:

	adv_params.type = BLE_GAP_ADV_TYPE_ADV_IND;
	adv_params.p_peer_addr = NULL; 
	adv_params.fp   = BLE_GAP_ADV_FP_ANY;
	
	p_whitelist_addr[0] = &whitelist_addr;

	whitelist.addr_count = 1;
	whitelist.pp_addrs = p_whitelist_addr;
	whitelist.irk_count = 0;
	whitelist.pp_irks = NULL;
	
	adv_params.p_whitelist = &whitelist;

[vldzero]

in on_adv_evt new lines are:

	ble_gap_addr_t whitelist_addr = 
	{
		BLE_GAP_ADDR_TYPE_RANDOM_STATIC,
		{0xfc, 0x45, 0x92, 0x76, 0xc4, 0x0c}  //my BT phone MAC address again
	};
	ble_gap_addr_t *p_whitelist_addr = &whitelist_addr;

and

				case BLE_ADV_EVT_WHITELIST_REQUEST:
					err_code = ble_advertising_whitelist_reply(p_whitelist_addr, 1, NULL, 0);
					APP_ERROR_CHECK(err_code);
					break;

when options.ble_adv_whitelist_enabled = true; it does not conect even though ble_advertising_whitelist_reply returns with NRF_SUCCESS When options.ble_adv_whitelist_enabled = false it connects...

[Petter Myhre]

Looks correct. You are connecting to a smart phone? What kind? Are you sure the address is correct? And the type? If you can upload your complete project I can try to test it here, if you want.

[vldzero]

I am connecting to a smartphone. CAT S60 (Android 6.01) using nrfConnect. I also just checked it with another one also with no success. The address is correct. Here you'll find the project Click

[Petter Myhre]

I tested your code. Seems to be working fine. Are you sure that also the address type is correct? You can check by letting the CAT connect (when you advertise without whitelist) and check

p_ble_evt->evt.gap_evt.params.connected.peer_addr.addr_type; 

when you get the BLE_GAP_EVT_CONNECTED event.