Sleep Mode Deep on E-Series

Hardware
1

Hey guys,

I’ve been working on a carrier board based around the E-Series Module, and everything works as expected… besides SLEEP_MODE_DEEP.

When I call System.sleep(SLEEP_MODE_DEEP, 60); in the code, the device goes to sleep but will never wake up again.

I am almost certain this happens because the RTC on E-Series is not getting power, so it doesn’t know when to wake up.

The Network Standby Sleep works perfectly, when I call:

System.sleep(D1, RISING, SLEEP_NETWORK_STANDBY, 60);

So this problem is only with SLEEP_MODE_DEEP.

I have the VBAT pin on the E-Series connected to the LiPo, which I thought was enough to keep it alive while in deep sleep.

If anyone could let me know what pins need to be powered for the E-Series to wake up from SLEEP_MODE_DEEP, it would be greatly appreciated!

2

When suspecting a misbehaviour of the device OS you should always state what version you are testing on.

If the device can't wake after the timeout it is possible that you had a HIGH level on the WKP pin when you entered deep sleep. To prevent that there is a "new" overload for System.sleep() that allows to disable the WKP pin.
https://docs.particle.io/reference/device-os/firmware/electron/#sleep-sleep-

System.sleep(SLEEP_MODE_DEEP, long seconds, SLEEP_DISABLE_WKP_PIN).

But if this is the case

your PCB should make sure the VBAT pin is permanently powered.
Either the way how it's done on the Electron via a 0Ohm resistor between 3v3 and VBAT or via a dedicated supply in the voltage range 1.65V .. 3.6V (e.g. coin cell) - not sure if connecting it to the LiPo (up to 4.2V) is a good idea tho'.

https://docs.particle.io/datasheets/cellular/e-series-datasheet/

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3

Sorry, this is running on DeviceOS1.0.0.

I used that SLEEP_DISABLE_WKP_PIN command and its working great now.

I have an external watchdog that was holding the WKP pin high… I should have caught that.
Thanks for the help.

On my next iteration of this PCB, should I tie 3V3 and VBAT together instead?
Is there any negative consequences using my current boards that connect VBAT and LiPo pins?

Thanks for your help!

4

I'd say driving VBAT beyond the specs will most likely not increase life expectancy of the devices.

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