How to do Proximity Search with nRF51422

[angel]

Hi guys,

I have two nrF51 dongles and I am really interested in making the pairing of both of them using the proximity search feature of ANT. So far what I did is, I took the broadcast example and converted it into an acknowledge message example. I do the pairing using the most simple mechanism I know: wildcard channel ID. Now this is working fine, but as I said, I want to use proximity search because I will get two or three more dongles and I want to pair them in different ways depending on the distance, or, for example, only pair the two closest to the master node.

I really don't know how to continue from here. Can someone give me some support with this?

Thanks!

[Petter Myhre]

I see two options:

-You can use sd_ant_prox_search_set() to do a proximity search, see Section 6.4 in ANT Message Protocol 5.1 and the Proximity Search application note, both available here.

-You can use a background scanning channel, and enable extended data format with Channel ID Output and RSSI Output.

[angel]

Hi Petter, thanks for your fast answer!

I will first try the first solution you mentioned. I have read more or less all the documentation you mentioned, and so far I think that I only have to send this sd_ant_search_set() message right before opening the channel. I have a doubt though: so far I set it only on the master, but the device keeps pairing even at 2 or 3 meters distance when I set it to the minimum. Is there more or less any relationship between these PROXIMITY_THRESHOLD_X and the distances? This config message, does it have to be set in both master and slave? only slave? only master?

Thanks!

[Petter Myhre]

I think you are correct, but you should only set this on the slave. The thresholds are RSSI values, and there is a relationship between RSSI and distance, but it depends on a lot of factors, so I can't give you a general formula, see this for more information.