New order of LoPy - deep sleep issues?

[mahe]

Hi,

I am contemplating ordering a couple more LoPy's. However I was quite dissapointed the last time I ordered when receiving a product that doesn't really live up to the specs.. It says:

– Ultra-low power usage: a fraction compared to other connected micro controllers

However even with the deep sleep shield (which also adds bulk) it seems that this isn't really the case..
Maybe I missed something, but I did not see any disclaimer anywhere when ordering, that it was basically not functioning as advertised - not very cool..

So I was wondering if we can expect a fix on the LoPy so that new orders will receive actual functioning products - or if it is a better bet to go for the LoPy4 maybe?

[sioo]

I'm using an Lopy4 powered by a Lifepo4 battery. For testing purposes I'm reading a sensor (bme280), sending the data using lora and then going to sleep for about 10 minutes.

[jcaron]

@sioo can you clarify your setup? LoPy or LoPy 4? Deep Sleep shield, expansion board, Pysense, PyTrack? Power source? Any active sensors?...

[sioo]

@dbrgn How did you get it down to 16.5uA? I'm currently reading around 30uA in deep sleep.

[dbrgn]

Since last time I tried the test script again, with the latest firmware (from 3 days ago). Now I get down to 16.5 uA. Not sure if the firmware is related.

Interesting is that when testing the same board on our custom hardware, I can get down to ~13uA. Maybe because some pins aren't floating anymore?

Anyways, it seems to be possible now to get below 20uA in deep sleep.

Edit: And I also sometimes experience the issue that the LED quickly lights up when waking up from sleep or when powering on the device for the first time.

[peekay123]

So, with the simple code below, the heartbeat LED pulses very briefly when my LoPy wakes from deep sleep.

[peekay123]

I'll give it a test tonight as well.

[beyonlo]

@robin I have not tested that.

[Robin]

@beyonlo have you also found that the LED flickers on after resetting from deep sleep?

[beyonlo]

@dbrgn All right, so that's two lines are unnecessary:

pycom.heartbeat(False)
pycom.wifi_on_boot(False)

[dbrgn]

I think I wouldn't even need to disable wifi on boot, since it should be off in deep sleep anyways.

[beyonlo]

@dbrgn Don't need to disable the Bluetooth/BLE too, like as you did with WiFi (pycom.wifi_on_boot(False)) ?

[dbrgn]

With nothing but the LoPy4 connected to the Otii (at 3.75V with auto range mode) I measure ~32uA in deep sleep.

Is this the best we can expect, or should it go lower?

This is the code (boot.py):

import machine
import pycom
pycom.heartbeat(False)
pycom.wifi_on_boot(False)
machine.deepsleep(15000)

As soon as I connect it to the expansion board (with all jumpers removed, power supply via JST connector) current goes to ~170uA.

[ssmith]

@robin I use this device. http://www.cmicrotek.com

You can also use a resistor in series with the 5V input and measure the voltage drop. You just have to size it correctly so you still get enough voltage to run the device. You also have to short it out till the device is asleep.

[bmarkus]

This tool can be also interesting

http://store.digilentinc.com/openscope-mz-open-source-all-in-one-instrumentation/

or a bit more expensive but more complex

http://store.digilentinc.com/analog-discovery-100msps-usb-oscilloscope-logic-analyzer-limited-time/

[danielm]

@jmarcelino
I was not aware of such device, are you satisfied with it? What are the most notable issues/drawbacks from you experience?
I am considering to buy it.

[jmarcelino]

@robin
I use this tool now, not the cheapest thing but very convenient.
https://www.qoitech.com

[danielm]

I use this tool:
http://www.eevblog.com/product/ucurrentgold/

Unfortunately, it seems to be out of stock.

[Robin]

@mahe
I have a LoPy4 in front of me and am considering how to test power consumption. Previously i had someone who helped with an oscilloscope, but that is a quite impractical for me at the moment. Is there another way to measure low power current drain from the battery? Presumably a multimeter is too imprecise?

[bmarkus]

@jmarcelino said in New order of LoPy - deep sleep issues?:

Thanks @danielm

Yes the L01 + baseboard combination will give you very low power deepsleep right now.

Any estimation what very low means?