CRC bytes in advertising data

[dblasco]

Hello,

I am implementing a central which is scanning for advertising packets using s130, SDK11, nRF51822 and based on example ble_app_hrs_rscs_relay.

I get the advertising packets in function

static void on_ble_central_evt(const ble_evt_t * const p_ble_evt)

in the event BLE_GAP_EVT_ADV_REPORT.

I can read from

const ble_gap_evt_t   * const p_gap_evt = &p_ble_evt->evt.gap_evt;

all the manufacturer data in

p_gap_evt->params.adv_report.data

However, I would like also to get the 3 bytes CRC that are included at the end of this data, but I cannot find the way to access to them.

How could I get these CRC bytes?

Thank you

[RK]

You can't get them - they are there as a checksum on the packet and stripped off before the data is passed to your application.

Why do you want them?

[dblasco]

I need them to know which advertising packets I have received and which not. I am building multiple devices acting as repeaters (they will advertise data that have heared). But I don't want to advertise the same data again, and I was planning to keep a database of CRCs to know which messages I have received.

[RK]

well you can always recalculate the CRC, or just use any hashing function you like to make a hash of the advertising data.