Delay before next join attempt

[Agathe Lee]

Hi!

I upgraded several of our mDots to the 1.0.8 firmware and have encountered (using them in Auto OTA mode) the following upon wake-up from sleep by interrupt:

Joining network…
Waiting 21 s before next join attempt
Network Joined

Now, is there a way to override this delay? Besides going back to previous firmware version? Our communication can’t afford that much latency. I have noticed wait times of anywhere between 4s and 41s so far…

Thanks,

Agathe

[Jason Reiss]

The session should be reloaded when you wake from sleep.

You could try to enable this setting.
AT+PS – Preserve session

The 1.0.8 firmware has session management functionality that can also be used in OTA mode. After a join you can save and restore the session info.
Be sure to save the session before going into deep-sleep mode.

AT+SS – save session
AT+RS – restore session

[Agathe Lee]

Thanks, Jason. Does this mean that at+sleep now enables a “deeper” sleep than what was possible on 0.1.4 firmware? I am trying to understand the differences between the two, and what there is to gain with the new firmware.
What are the differences in sleep modes? which one is the default? Any differences in power consumption between them?

[Jason Reiss]

I believe you will find your answers in our updated documentation.

Here is the updated AT Command Guide for 1.0.8
http://www.multitech.com/manuals/s000643_1_1.pdf

Here is the updated Developer Guide for 1.0.8
http://www.multitech.com/manuals/s000612_2_0_7.pdf

Thanks,

Jason

[Agathe Lee]

Alas, I was asking because these documents, which I have, do not shed much light on the differences between sleep modes (So, one means that ST Micro is stopped, while the other means it’s in standby, for a user, what does that mean? In terms of what do I need to save, what do I need to restore, how long does it take to wake up from each type of sleep, and what is the idle current draw of each, the manual, page 21, offers two conflicting answers)

Thanks,
Agathe

[Jason Reiss]

The ST Micro STANDBY is the lowest power mode. All RAM is lost and peripherals are off. Backup registers can be used to retain state over sleep. The libmDot will keep running state in the backup registers to be reloaded automatically so the session will be maintained. Execution begin at the start of the program as it would from power-up.

With ST Micro STOP RAM is maintained and peripherals are on. Execution resumes from the call to sleep.

Waking up from Stop mode takes 13-14 μsec.
Waking up from Standby mode takes 314-407 μsec.
RTC time period is 30.5 μsec.

These values have to be taken into account if you need to wake-up on a specific 1 msec timehack.

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