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CC3000 connecting time

Hi,

I'm having working system with PIC32 and CC3000 module. I've run some measurements of my setup, and I get some results that confuses me. I measured time to establish connection with AP (I've used Mikrotik). I've measured required time to establish connection in two scenarios: when CC3000 has to scan all channels, and when it was set to scan only working channel of my AP. Time I've measured was from point when wlan_connect command was issued until HCI_EVNT_WLAN_UNSOL_CONNECT event. Working AP channel was channel with lowest interference (no other AP in vicinity operated on that channel). Fast connection nor smartprofiles were used, but all SSID parameters were passed on wlan_connect command.

In fist case I've got that CC3000 requires some 1.2 seconds to HCI_EVNT_WLAN_UNSOL_CONNECT event (+/- few miliseconds). And that's fine.

However, in second case, I've got two bins. In one bin it took it 1.059second (+/- few milisecond) to establish connection, while in second bin I've measured around 60ms. Nothing in between, it is either 60ms or 1second. I've run something like 50 runs, and number of events in each bin is approximately equal (50%). Now, I'm confused why I'm seeing those two bins, why is there so huge difference between them, and what can be cause of it. Does anybody has any idea or suggestion?

Thanks.

Regards,

Boris

  • It seems that this issue is related with parameters of wlan_ioctl_set_scan_params function. If both, MinDwellTime and MaxDwellTime are set below 100 ms, connection time is consistent and always around 50ms. If I set MinDwellTime and MaxDwellTime are higher than 100ms, connection time is consistent and always higher than 1 second. However, if MinDwellTime is set to 20ms and MaxDwellTime is set to 100 ms, connection time is sometimes 50ms and sometimes 1 second. All other settings do not have any effect on this behavior. As, before, CC3000 should scan only one channel.

    Does anybody have any idea how channel scanning is implemented in CC3000, what are MinDwellTime and MaxDwellTime, and why they influence connection time in this way. Any suggestions would be welcome.

    Regards,
    Boris