How to change the mac address when the system boots up?

[Ben.Qin]

As said on the topic "GAP Address types", the random static address can be changed when system boots up. I can't find any content about how to make it. Could anyone offer any tips? best regards!

[Håkon Alseth]

Check out the function "sd_ble_gap_address_set" in ble_gap.h. Here's an example:

ble_gap_addr_t gap_addr;
gap_addr.addr_type = BLE_GAP_ADDR_TYPE_RANDOM_STATIC;
// "my_random_addr" must be random generated.
memcpy(&gap_addr.addr, my_random_addr, sizeof(gap_addr.addr));
gap_addr.addr[5] |= 0xc0; // 2 MSBit must be '11' for RANDOM_STATIC address, see v4.0, Vol 3, Part C, chapter 10.8
err_code = sd_ble_gap_address_set(gap_addr);
APP_ERROR_CHECK(err_code);

[Artem Zemlyanukhin]

Hi,

in what type of memory will be written to the new address? what will be with this address after reset?

Best regards, Artem

[Håkon Alseth]

This will be stored in the softdevice's RAM. This means that you will have to set the custom address, using the above sd_-call, on every boot up.

[Sarah]

Where would be a good place to include this code if we are using the sample beacon project? I currently cannot find where in this sample project, the function sd_ble_gap_address_set() is being called. I'm quite new to nRF programming, so I would appreciate if you could give some basic instructions.

[Håkon Alseth]

Hi Sarah, You can place this code in the init, after ble_stack_init().

Cheers, Håkon