Disabling AFH (Adaptive Frequency Hopping)

[takashina hiroki]

Please tell me about AFH (Adaptive Frequency Hopping).

SDK：15.3.0
例：ble_app_multirole_lesc
DeviceA：EYSHJNZWZ（nRF52832）

In AFH (Adaptive Frequency Hopping), the frequency is switched between 0 to 36 CH when connected and 37 to 39 CH when advertised.
Is it possible to disable AFH?
In other words, is it possible to fix to any channel?
Please tell me if there is a way.

[Dmitry]

Just to note that such configuration will not match Bluetooth specification that says: The minimum number of used channels shall be 2.

[takashina hiroki]

Thank you for answering.

Is communication impossible when the number of channels is set to 1?
I want this setting for debugging purposes.
Eventually use AFH.

[Dmitry]

I believe it's possible, I can't say for sure. Try to mask all but one channel:

 ble_opt_t opt;
 memset(&opt, 0, sizeof(opt));
 opt.gap_opt.ch_map.ch_map[0] = 0xFE; // ch.1
 opt.gap_opt.ch_map.ch_map[1] = 0xFF;
 opt.gap_opt.ch_map.ch_map[2] = 0xFF;
 opt.gap_opt.ch_map.ch_map[3] = 0xFF;
 opt.gap_opt.ch_map.ch_map[4] = 0x1F;
 sd_ble_opt_set(BLE_GAP_OPT_CH_MAP, &opt);

takashina hiroki said:

Can I disable AFH in the same way when advertising as a peripheral device?

There is no AFH when advertising, instead, device is advertising sequentially on all 3 channels. Yes, you can change advertising channel mask in ble_gap_adv_params_t.

[takashina hiroki]

I understood it.
I will try it.