5 years, 10 months ago.

Microcontroller is reseting when returning from sleep


I am working with some mDots. With this mDot_LoRa_Sleep_Example program some of them seem like the microcontroller is reseting when it returns from sleep state. Does anybody have this behaviour or issue?

Thank you and regards,


Question relating to:

Connecting to gateway, sending packets with a MultiTech mDot and entering deepsleep mode between transmissions. Lora, low power, mdot, multitech, Sleep

I guess I have found a work around for that one. You can use deepsleep() function available on mbed that puts the controller to sleep but keeps the peripheral clocks running.

posted by Abhimanyu Dhone 06 Apr 2016

2 Answers

5 years, 10 months ago.

The Cortex M4 has 3 sleep modes (SLEEP, STOP and STAND-BY).

The current mDot firmware will put the device into the lowest sleep mode, STAND-BY. When STAND-BY returns it is much like a reset as the RAM has been lost.

In our next firmware we will support the STOP mode that will preserve RAM.

Accepted Answer

Thats good to know Jason. Do you have a timescale for when the next release of the library will be available?

posted by Andrew Lindsay 15 Mar 2016

OK jason. So the actual library only supports STAND-BY mode. In my last comment I have made a mistake, the old hardware version is reseting too. I will wait to the new libmdot version. In the meantime, my application will have to function without sleep. Thank you for the information. Gilen

posted by Gilen Tell 15 Mar 2016

Can you suggest me a way to turn on/off the radio on the mDot?

posted by Abhimanyu Dhone 06 Apr 2016
5 years, 10 months ago.

I believe this is the normal behaviour as I have not seen any other way the mDot wakes up. I'm not sure if this is because the low power mode does not preserve RAM so has to perform a full restart on wakeup.


It can´t be the normal operation. The cortex M4 preserves RAM in sleep. I have a mDot unit of previous hardware version that doesn't reset when it is standalone, but this unit resets when it is inserted in MTUDK2-ST starter kit. The new hardware version mDots always reset returning from sleep. I think that the difference in hardware is a new regulator or LDO, because the old one had excesive current consumption. Is this a hardware issue or a libmdot bug? Thank you and regards, Gilen

posted by Gilen Tell 15 Mar 2016