How to obtained BLE frequency hopping table from SoftDevice

[rav4]

Hi,

I am using radio time slot to run a second RF communication link.  The device is connected to a host (mobile phone) via BLE.  May I know how to obtain the BLE frequency hopping table (current BLE link) from SoftDevice so that I can either reuse or avoid the channels.

thank you.

[haakonsh]

Hey rav4,

There's no API to fetch the current channel map, but as long as you've not disabled a data channel then all data channels are used. If you have disabled one or more data channels then you already know the channel map. 

Cheers,

Håkon.

[rav4]

Håkon,

I understand that BT/BLE uses adaptive frequency hopping mechanism where central/device will mask out the channels used by Wifi.  Is this applicable in my use case? 

By the way, how to disable data channel?  Which API to use?

thanks.

rav4

[haakonsh]

BT/BLE does not yet use adaptive frequency hopping, you have to manually disable channels with a call to sd_ble_opt_set where you pass a ble_gap_opt_t of ble_gap_opt_ch_map_t.

See also ble_gap_ch_mask_t. 

[Dmitry]

In fact, host sometimes updates channel map. You can try to use sd_ble_opt_get() with BLE_GAP_OPT_CH_MAP  to read channel map.

[rav4]

Hi Håkon,

thanks.  I managed to read back the channel map.  May I know how to decode the value?  All the channels are marked with '0'?  Does it mean all channels are used?  Or the value is invalid.  The channel map was read at 1 second interval for testing purposes.

thanks.