Time to connect to wifi long, reduce current consumption

In our battery powered application 50% off the battery is used up because IMP is trying to connect. Connect time strongly depends on wifi/network. I logged microseconds to connect to wifi. Often it connects after 3 seconds, but if it doesn’t connect, the next possible time to connect is about 2 seconds later and in the mean time it is wasting battery power. Why is it waiting 2s? And why is it wasting battery power while waiting. Do you have tips to improve battery life?

Which release is this on?

There are many things that could happen there; it may be the association failing and being retried (which we retry immediately when we’re told it failed), it may be not getting a DHCP reply (which I believe may be retried after 2s, but the time intervals are set by the DHCP spec), it could be no reply to a TCP SYN hence a TCP retry interval, etc.

If you have wireless captures of slow connects (wireshark in monitor mode on an unencrypted network) then more detail can be gleaned about this.

Still, ~3 seconds seems like a long time compared to what I see in the office, where it’s typically around 1s from a cold boot.

I use developer IDE and it showed Device firmware version: 78f540f - release-32.12 - Thu Jul 16 09:55:33 2015. It just updated impOS. What can you tell about the releases?

In the future (after 6 weeks) I will further investigate the time it takes to connect to wifi and use tools like wireshark.

In the oldest post I added a picture, why is it gone now?

I can see the picture here?

32 uses an older Broadcom firmware than release 30 did as we found that connect times were on average slower with the newer one.