Scan for other devices using nrf51422 PCA10028

RE: Scan for other devices using nrf51422 PCA10028

Petter Myhre — Tue, 20 Oct 2015 12:02:18 GMT

You don't need to post everything, since the questions are not really related. Just add a new question, something like "How to advertise for less than 1 second?"

RE: Scan for other devices using nrf51422 PCA10028

Artucas — Tue, 20 Oct 2015 11:58:24 GMT

Sure. Do you want me to create new question and post everything i did to make this work, or just add the question and you will fix things up? I can make a short review how i did this and add it as an answer below newly created question. :)

RE: Scan for other devices using nrf51422 PCA10028

Petter Myhre — Tue, 20 Oct 2015 08:47:10 GMT

Thank you for the feedback. Appreciate it. Could you add this question as a new question? This is getting a bit cluttered.

RE: Scan for other devices using nrf51422 PCA10028

Artucas — Mon, 19 Oct 2015 06:57:50 GMT

Hello, i wanted to give a feedback and ask few last questions :) So i did what i need in my application: I'm scanning for devices and give a report when a device with specific address, which i know, is found. Then i start advertising for some time, actually for 1s, using APP_ADV_TIMEOUT_IN_SECONDS which you have mentioned. after i receive this event in a handler, i start to scan again and so on. Everything is tested and works fine. So thank you very much for your support, i'm accepting your answer now :) And the last question for this topic: stopping advertise after 1s is okay for now. But later i might be forced to lower the advertising time, so in case i need to stop advertising lets say after 250ms, how would you recommend to do it? just start advertising, and after advertising start function put a delay of 250ms, then stop? Would power consumption go up in this case? Thanks in advance. :)

RE: Scan for other devices using nrf51422 PCA10028

Petter Myhre — Fri, 16 Oct 2015 15:01:51 GMT

If sd_ble_gap_adv_stop() returns an error and you then call APP_ERROR_CHECK you will end up in app_error_handler in a while(true) loop. This will happen if you call it when you are not advertising, because you will get NRF_ERROR_INVALID_STATE. So you can either handle(ignore) the error, so something like:

err_code = sd_ble_gap_adv_stop();
if(err_code == NRF_ERROR_INVALID_STATE)
{
     err_code = NRF_SUCCESS;
}
APP_ERROR_CHECK(err_code);

Another option is to set the advertising timeout (APP_ADV_TIMEOUT_IN_SECONDS). But the minimum timeout is 1 second. Then you don't need to call sd_ble_gap_adv_stop() at all.

RE: Scan for other devices using nrf51422 PCA10028

Artucas — Fri, 16 Oct 2015 14:30:02 GMT

Woops, my mistake. Actually the code is working. But could you check if it is okay if i stop advertisements like this? I mean is it allowed, won't i cause hard fault or something if i'll try to stop advertise while it is going? because i don't know if device is advertising at the time i am calling sd_ble_gap_adv_stop(); function. Still keep an eye of this post if still possible :) Thanks.

RE: Scan for other devices using nrf51422 PCA10028

Artucas — Fri, 16 Oct 2015 12:53:47 GMT

Hey, it seems like i am having another problem right now. After looking at some ble_central examples, i was able to trigger certain actions only after my device with known address is found. Thats good news :) After that, i want to start advertising for about 250-500ms and then stop advertising. And thats the point at which i am stucking. After i found my device, i am stopping a scanner and starting to advertise some data, and i am not able to stop that advertisement. Now i am trying beacon example to stop advertisements, could you look at the code and explain why i'm not able to stop advertisements in this way? Regards. Code: http://pastebin.com/e57Yj0ye

RE: Scan for other devices using nrf51422 PCA10028

Petter Myhre — Thu, 15 Oct 2015 10:30:07 GMT

Great! You accept the answer by clicking the grey circle next to my answer, but thanks for the vote. I'll keep track. You can wait with the accept until you got this working.

RE: Scan for other devices using nrf51422 PCA10028

Artucas — Thu, 15 Oct 2015 10:23:28 GMT

Thanks for your help. Looked at ble_central examples and it seems like i'll be able to do what i want. Ill come back here with a feedback within a few days or so, so if you are able please keep a track of this post, in case ill have some more questions... ;) Right now ill accept your answer and thanks again. Regards.

RE: Scan for other devices using nrf51422 PCA10028

Artucas — Thu, 15 Oct 2015 09:13:56 GMT

Thank you for your answer, but this isn't exactly what i want. I don't need to connect to that device. In experimental_ble_app_hrs_scanner example there is a beacon_evt_handler, which is called every time the scanner founds some device. What i want: I want this function called only when, when scanner finds a device with a specific address which i know, but i dont want to connect to it. I just want to find that device, and then advertise some data for some time. I don't need to connect to that device. And another question i have is this: All the examples that are comming from nrf for scanning for devices, are made with Time Slot API? Are there any other examples for scanning for devices than experimental_ble_app_hrs_scanner? Thank you for your help. Regards

RE: Scan for other devices using nrf51422 PCA10028

Petter Myhre — Wed, 14 Oct 2015 11:29:54 GMT

You can tell the SoftDevice to connect to a specific address or IRK.

The radio will still receive all advertising packets, but if there is IRK or address match the packets will be ignored.

You can use the following function for this.

sd_ble_gap_connect(ble_gap_addr_t const *p_peer_addr, ble_gap_scan_params_t const *p_scan_params, ble_gap_conn_params_t const *p_conn_params));

So you can either set the address (not IRK) to p_peer_addr and don't use whitelisting. Or you can set p_peer_addr to NULL and add the address (or IRK) to the whitelist. If you have more than one address/IRK in the whitelist it will connect to the first valid advertising packet it receives.

Edit 15.10.2015

experimental_ble_app_multiactivity_beacon is a peripheral example. Peripherals don't usually scan, but here we added scan functionality by using the timeslot API.

Have a look at the examples in ble_central folder instead of ble_peripheral.

You start a scan by using sd_ble_gap_scan_start().

Then you will get the BLE_GAP_EVT_ADV_REPORT event every time the SoftDevice receives an advertising packet.

It will come together with ble_gap_evt_adv_report_t struct which contains the peer address. You can compare this with the known address and trigger an action if there is a match.

Or you can provide a whitelist to sd_ble_gap_scan_start(). In the whitelist you add the known address or IRK of the peripheral.

Then you will only receive the BLE_GAP_EVT_ADV_REPORT event when the SoftDevice receives and advertising packet from those devices.