RE: What is the relationship between the BLE address and the various FICR registers?

Edvin — Wed, 31 Jul 2019 13:43:48 GMT

No worries. Happy to help 🙂 Maybe someone else who has the same questions in the future will find this post helpful, so no need to apologize.

Best regards,

Edvin

RE: What is the relationship between the BLE address and the various FICR registers?

Acutetech — Wed, 31 Jul 2019 12:58:35 GMT

Hi Edvin

First, thanks for pointing out my coding error (DEVICEADDR[0] etc). When I read NRF_FICR->DEVICEADDR[0] and NRF_FICR->DEVICEADDR[1] I now get this result, with the board address shown as originating from DEVICEADDR:

<info> app:    Board address = E2:2A:8F:50:F5:A3
<info> app:     addr_type=1, addr_id_peer=0
<info> app:    DEVICEADDRTYPE: FFFFFFFF
<info> app:    DEVICEID[0]: 4BC5E0FB
<info> app:    DEVICEID[1]: 75CAE81E
<info> app:    DEVICEADDR[0]: 8F50F5A3
<info> app:    DEVICEADDR[1]: 7483622A

In the case of my own app, you guessed correctly: I was calling sd_ble_gap_addr_get() too soon (error code was 02). When I move this call after the softdevice is initialised it works the same as above.

My apologies for my simple errors and thank you for your quick response!

RE: What is the relationship between the BLE address and the various FICR registers?

Edvin — Wed, 31 Jul 2019 12:06:04 GMT

Hello,

A1:

[quote user=""]

    NRF_LOG_INFO("   Board address = %02x:%02x:%02x:%02x:%02x:%02x",
           boardAddress.addr[5], boardAddress.addr[4], boardAddress.addr[3],
           boardAddress.addr[2], boardAddress.addr[1], boardAddress.addr[0]);
    NRF_LOG_INFO("    addr_type=%d, addr_id_peer=%d", boardAddress.addr_type, boardAddress.addr_id_peer);
    NRF_LOG_INFO("   DEVICEADDRTYPE: %08X", NRF_FICR->DEVICEADDRTYPE);
    NRF_LOG_INFO("   DEVICEID0: %08X", NRF_FICR->DEVICEID[0]);
    NRF_LOG_INFO("   DEVICEID1: %08X", NRF_FICR->DEVICEID[1]);
    NRF_LOG_INFO("   DEVICEADDR: %08X", NRF_FICR->DEVICEADDR);

The output is as follows:

<info> app:    Board address = E2:2A:8F:50:F5:A3
<info> app:     addr_type=1, addr_id_peer=0
<info> app:    DEVICEADDRTYPE: FFFFFFFF
<info> app:    DEVICEID0: 4BC5E0FB
<info> app:    DEVICEID1: 75CAE81E
<info> app:    DEVICEADDR: 100000A4

[/quote]

It is actually the DEVICEADDR that is the BLE address, not the DEVICEID. I see that you missed one thing when printing the DEVICEADDR. Like the DEVICEID registers the DEVICEADDR is two registers. Try to print:

NRF_LOG_INFO("    DEVICEADDR0 %08x", NRF_FICR->DEVICEADDR[0]);
NRF_LOG_INFO("    DEVICEADDR1 %08x", NRF_FICR->DEVICEADDR[1]);

Right now it only prints the address where the DEVICEADDR register is located, 0x1000000A4, which you can see here. (baseaddress: 0x10000000, offset 0x0A4)

It says in the description of DEVICEADDR (from the link):

48 bit device address
DEVICEADDR[0] contains the least significant bits of the device address. DEVICEADDR[1] contains the most significant bits of the device address. Only bits [15:0] of DEVICEADDR[1] are used.

So only 2 bytes of DEVICEADDR are used. Also, the 2 MSBits of the BLE address has to be '11' according to the BLE spec.

You may notice (but it may not be the case on your device) that some bits of DEVICEADDR are "wrong" compared to the board address that you check with sd_ble_gap_addr_get(); This is because the some address bits are tied to the address type. So if your deviceaddr says 0x65, the address will be 0xE5, given that you use a random static address.

A2:

These values look semi-random. Do you fetch them the same way as you did in Q1? Where in the project do you do it? Before or after the softdevice is initialized? Does sd_ble_gap_addr_get() return 0? Try:

ble_gap_addr_t boardAddress;
ret_code_t err_code;
err_code = sd_ble_gap_addr_get(&boardAddress);
if (err_code == NRF_SUCCESS)
{
    NRF_LOG_INFO("   Board address = %02x:%02x:%02x:%02x:%02x:%02x",
            boardAddress.addr[5], boardAddress.addr[4], boardAddress.addr[3],
            boardAddress.addr[2], boardAddress.addr[1], boardAddress.addr[0]);
    NRF_LOG_INFO("    addr_type=%d, addr_id_peer=%d", boardAddress.addr_type, boardAddress.addr_id_peer);
    NRF_LOG_INFO("   DEVICEADDRTYPE: %08X", NRF_FICR->DEVICEADDRTYPE);
    NRF_LOG_INFO("   DEVICEID0: %08X", NRF_FICR->DEVICEID[0]);
    NRF_LOG_INFO("   DEVICEID1: %08X", NRF_FICR->DEVICEID[1]);
    NRF_LOG_INFO("   DEVICEADDR: %08X", NRF_FICR->DEVICEADDR);
}
else
{
    NRF_LOG_INFO("sd_ble_gap_addr_get() failed with err_code 0x%x", err_code);
}

What does it say?

Best regards,

Edvin