Correction for AT+SDUR instructions in the AT command wiki

[Waywayway]

Just got my BlueDuino and started playing around with it. Soldered the pins in place, plugged in the USB wire, and uploaded the serial sample sketch. Amazing. It works.

Found one problem with the wiki instructions though. Regarding AT+SDUR, the AT command wiki says:

"AT+SDUR[param1] Scan duration in seconds AT+SDUR1 OK+Set:1"

First of all, you should probably add a note that the default is 4 seconds.

More importantly, you should add note:

"Run AT+RESET to make the command affected"

oops, that's not very good English. How about this instead:

"Run AT+RESET to activate the new duration timing"

In other words, simply using AT+SDUR command does not actually change the duration. Even though "AT+SDUR?" will return the duration that you just adjusted to, it's not actually in effect until you reset the module.

[aprilpea]

I've just added the line to the wiki.

Thank you very much for your mention.

[Waywayway]

Quick question: When I set the AT+SDUR to 1 second, does that mean the scan interval and scan window are both set to 1 second? (assuming I am using AT+SCAN2 for scanning)

[aprilpea]

It just mean scan interval is set to 1 second. The scan window is default value and I haven't found it at TI's document.

Do you need a shorter scan interval?

[Waywayway]

No, I'm just trying to get very reliable scans, 1 per second.

I currently have an iBeacon set to advertise once per second.

And now I have set the BlueDuino to AT-SDUR1 (i.e. 1 second scan duration).

So, in theory, the iBeacon is advertising once per second, and the BlueDuino is scanning for one second, sooooo it should capture every single advertisement from the iBeacon and I should get 1 scan result per second, but....

When I run a simple sketch, I get too much variability in the scan results. For example, here's what I get in the serial monitor (the RSSI number is incorrect; just ignore it):

The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 965
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1010
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1976
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 963
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1011
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 963
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1012
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 964
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 3947
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1976
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1010
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 962
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1977
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1011
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 963
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1014
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 964
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 2986
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 963
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1012
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1972
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 962
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1014
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 963
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 2986
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1984
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 963
The RSSI of the target bluetooth LE 4.0 fob is: 2
Milliseconds elapsed since last string: 1011

You can see from the bolded numbers above that I am getting slow scans every few seconds. Not sure why though.

I am currently trying a different approach where the sketch writes AT+SCAN2 then reads results for 1 second, then writes AT+SCAN0 (stops scanning), then loops back to write AT+SCAN2 again, etc etc. It seems to be getting better results, but still not all 1 second scans.

So I am still brainstorming how to get 100% reliable 1 second scans. That's why I asked the question about scan interval and scan window.

[aprilpea]

Please try to change the advertising interval to shorter. For example: 500ms or less. The beacon will advertise at three channels. BlueDuino may miss the advertising data.

[Waywayway]

Please try to change the advertising interval to shorter. For example: 500ms or less. The beacon will advertise at three channels. BlueDuino may miss the advertising data.

Haha, yes, I know that will help. But I am developing a consumer product and want the iBeacon to last as long as possible without needing a battery change. So, I need to stay at 1 advertisement per second.

Your point about three channels is interesting though. I will think about it some more. Thanks!