Central - use public address

[M]

Hi. I'm new to Nordic BLE devices. Using the nrf51-DK. I have a peripheral device (non-Nordic) which I want to connect to from a Nordic central (S130) using the public address. It seems that by default the address used by the central is the random one. Is this possible? How can I do this? Thanks.

[Jørgen Holmefjord]

Hi,

There should be no difference in the way you connect to a peripheral with a public or a random address.

The softdevice function sd_ble_gap_connect() takes a pointer to the address struct, ble_gap_addr_t, as agrument. This should be filled with the address and the address type. By setting the type to BLE_GAP_ADDR_TYPE_PUBLIC, you can connect to a device that has a public address.

If your central is scanning for advertising packets from the device before connecting, you can pass the address struct included in the advertising report, peer_addr, directly to the connect function.

Best regards,

Jørgen

[Jørgen Holmefjord]

If you set the address type to BLE_GAP_ADDR_TYPE_RANDOM_STATIC, the address will be constant but not entirely unique, as it is randomly generated during production. However, with 2^46 combinations of addresses, the chance of getting two devices with the same address is practically zero. As long as you do not call sd_ble_gap_address_set() anywhere in your code, this is the default behaviour of the softdevice, so you should not have to change anything. The FICR registers cannot be changed, meaning your device will keep the same address for its whole lifetime.