Disabling AFH (Adaptive Frequency Hopping)

RE: Disabling AFH (Adaptive Frequency Hopping)

takashina hiroki — Fri, 20 Dec 2019 03:58:53 GMT

Thank you for answering.
I will try it.

RE: Disabling AFH (Adaptive Frequency Hopping)

Jimmy Wong — Thu, 19 Dec 2019 06:40:07 GMT

You can use the channel survey and do the channel map update from central.
The example code is here.
https://github.com/jimmywong2003/nrf52-central-channel-map-update-with-survey

RE: Disabling AFH (Adaptive Frequency Hopping)

takashina hiroki — Thu, 19 Dec 2019 04:32:24 GMT

I understood it.
I will try it.

RE: Disabling AFH (Adaptive Frequency Hopping)

Dmitry — Wed, 18 Dec 2019 09:33:59 GMT

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);

[quote userid="72172" url="~/f/nordic-q-a/55715/disabling-afh-adaptive-frequency-hopping/225994"]Can I disable AFH in the same way when advertising as a peripheral device?[/quote]

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.

RE: Disabling AFH (Adaptive Frequency Hopping)

takashina hiroki — Tue, 17 Dec 2019 23:38:12 GMT

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

RE: Disabling AFH (Adaptive Frequency Hopping)

takashina hiroki — Tue, 17 Dec 2019 23:35:01 GMT

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.

RE: Disabling AFH (Adaptive Frequency Hopping)

takashina hiroki — Tue, 17 Dec 2019 22:52:35 GMT

Thank you for answering.

Can "sd_ble_opt_set" be used only on the central device?
Can it be used from a peripheral device?

Also, I'm not sure how to use "sd_ble_opt_set".
For example, what should be specified for "opt_id"?
Are there any samples that use "sd_ble_opt_set"?

RE: Disabling AFH (Adaptive Frequency Hopping)

Dmitry — Tue, 17 Dec 2019 09:27:11 GMT

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

RE: Disabling AFH (Adaptive Frequency Hopping)

bjorn-spockeli — Tue, 17 Dec 2019 09:22:58 GMT

Hi Hiroki-san,

it is the Central device that dictates the channel map used in a connection and it can be modified through the sd_ble_opt_set API, see S132 SoftDevice v7.0.1: ble_gap_opt_ch_map_t Struct Reference. So by removing all but one channel from the channel map, you should be able to restrict communication to a single channel.

Best regards

Bjørn