New order of LoPy - deep sleep issues?

[mahe]

I never received any replies here. I needed some extra LoPy's for testing, so I ordered some even though I didn't expect to receive anything different from last time. If low power consumption is needed the LoPy is not the way to go. Maybe the LoPy4 is better, but I haven't seen any examples..

I must admit, that I feel Pycom is using false advertisement in regards to the LoPy. It still says:

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

on the product page. I don't see anywhere mentioned that this is not true - even with the low power shield (which as far as I can see is not mentioned anywhere either - even though it radically changes the form factor of the LoPy).. The first time I ordered I had no idea that the product I would receive was completely useless for my application..

[jmarcelino]

Hi @robin,

The LoPy4 is not finished yet and we don't have final production hardware. We'll have full power consumption results when it's released.

That'll will happen closer to end of this month.

[danielm]

I am able to achieve 16uA deep-sleep current using LM3281 voltage regulator and L01 OEM module. LoPy4 will carry different Semtech chip if I remember correctly.

You may try to use L01 + OEM baseboard from Pycom.

[jmarcelino]

Thanks @danielm

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

The LoPy4 does have a different Semtech chip SX1276 but the power specifications difference from that isn't major.The other difference is a TCXO (temperature compensated crystal). But in terms of deepsleep that shouldn't matter.

We'll have detailed official numbers (deepsleep, sleep, transmit, receive) later in the month. I'm expecting to present it at The Things Conference.

[jcaron]

@jmarcelino should probably update the web shop then, it still says

Purchasing the LoPy4 means you are pre-ordering ready for shipment 27th December 2017

(Twice)

While we’re on that topic, what’s the status on the new cases?

[jcaron]

Welcome to the twilight zone...

The LoPy4 is not finished yet and we don't have final production hardware. We'll have full power consumption results when it's released.

That'll will happen closer to end of this month.

But then you post on Twitter:

Yay! The NEW LoPy4.0 is shipping :) Come and try out our new #LoRa #Sigfox #WiFi #BLE @ESP32net @LoRaAlliance @sigfox #IoT developer board #GOINVENT

(and I notice the shipment date warning has been removed from the web shop).

Oh, it seems the new cases have been pushed back to... April!

[jmarcelino]

@jcaron

Yes, the LoPy4 hardware has arrived earlier and is actually shipping today (I was surprised myself to learn this).

However the software side is still being worked on so I can't offer power consumption figures yet, they'll definitely be done by end of month but hopefully sooner.

[Robin]

@jmarcelino and @mahe and @livius
I ordered LoPy4's today on the webshop. They were picked up by DHL this afternoon so i should have them next week. Will let you know how i get on with the following:

• Power consumption
• RTC being reset every sleep cycle
• Unpredictable sleep intervals

[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?

[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?

[danielm]

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

Unfortunately, it seems to be out of stock.

[jmarcelino]

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

[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.

[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/

[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.

[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.

[beyonlo]

@dbrgn Don't need to disable the Bluetooth/BLE too, like as you did with WiFi (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 All right, so that's two lines are unnecessary:

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

[Robin]

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