KW36 BLE advertising interval 30s or 60s

[no6524]

I am working on BLE project with the KW36.

The advertising interval is currently configured to be 10s (16000 in units of 0.625ms).

I would like to change this to 30s and 60s (in different modes of my device). When I increase the values of minInterval and maxInterval for calling Gap_SetAdvertisingParameters, I no longer see any advertisement packets. Is there an upper limit to the minInterval and maxInterval values ?

Another question : what is the purpose of having two values (minInterval and maxInterval) for advertisement ? I understand for connection intervals but not for advertisement interval.

I know the BLE specification is limited to 10.24s but I don't intend to be Bluetooth SIG compliant so I don't really care.

[mario_castaneda · Accepted solution]

Hi @no6524,

I hope you are doing great.

Is there an upper limit to the minInterval and maxInterval values ?

Yes, you have some max and min limit values

For example: adv_fast_interval1, adv_fast_interval2, adv_slow_interval, etc. Please look at the Table A.1 in the Bluetooth SIG Spec.

Another question : what is the purpose of having two values (minInterval and maxInterval) for advertisement ?The ADV will send at the beginning using the min interval to send it and after that, if It doesn't receive any scan response could start to use the max interval, that is for the low power purpose.

You have to options to implement this.

1. You could use the periodic advertising events  4.4.2.2.3 Periodic advertising events or you could send adv for 1 second for example and stop the adv, use a timer and after 30 seconds you could send it again.

2. You could implement the beacon using the GFSK example, but you have to implement all the routing for the adv packet.

Regards,

Mario

[no6524]

Hi Mario,

Thanks for your suggestions.

When looking at the GAP time table, I see Tgap(103) : Minimum time span that a device is in discoverable mode. This is a required value of 30s. Does that mean that in theory when I start advertising, I should always advertise for at least 30s ? That is my understanding of the specification but I am not sure. If I am right, then it means that the first suggestion would therefore not be compliant (although I don't really care about compliancy).

I was actually planning to use GenFSK but my device will need at some point to become connectable (especially for enabling resolvable private MAC addresses). I don't think this is possible to do with GenFSK, is it ?

Regards.

[mario_castaneda]

Hi @no6524,

You are right, that is the Minimum time span that a device is in discoverable mode. However, you could go to sleep mode for a specific time depending on your application.

Regards,

Mario