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Adafruit Feather HUZZAH ESP8266 Power Consume
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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by hadim on Thu Mar 07, 2019 12:56 pm

What is the difference in the design that makes it consumes more than the Sparkfun ESP8266? According to this blog post https://openhomeautomation.net/esp8266-battery, its consumption can go as low as 77 uA!

From the photo, it looks like the board also has a USB-to-Serial converter.

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by adafruit_support_mike on Fri Mar 08, 2019 2:13 am

The Sparkfun ESP8266 Thing that has a LiPo connector doesn't have a USB-to-Serial converter, and has to be programmed with an external USB-to-Serial cable.

The ESP8266 Thing Dev Board that does have an onboard USB-to-Serial converter doesn't have the option to run from a LiPo.

The power issue on the Feather involves the connections between the USB 5V line, BAT for the LiPo, and the way the CP2104 USB-to-Serial converter gets its power.

The CP2104 can take power directly from the USB cable, which makes sense. When you connect a device to a USB host, there are valid reasons for its USB interface to be active, even if other parts of the system are shut down. On a Feather, the 5V and BAT traces both connect to the onboard 3.3V regulator, so the CP2104 could power itself parasitically from the LiPo even when the board wasn't connected to a USB host.

That specific set of connections doesn't exist on any of the ESP82366 Thing boards.

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by matthijskooijman on Fri Mar 08, 2019 6:38 am

matthijskooijman wrote:Ah, nice. Could you give a preview of the (relevant part of) the new schematic? Perhaps (in a branch on) github? I'm curious how you solved this, and might perhaps see if I can modify my revE huzzah in a similar way :-)


This question has gone unanswered and I'd like to still see it answered :-) It refers to the upcoming revF schematic for the ESP8266 Huzzah that @adafruit2 mentioned.

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by hadim on Fri Mar 08, 2019 8:12 am

Thank you Mike for the clear explanation.

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by adafruit2 on Sat Mar 09, 2019 8:01 pm

matt, this is completely untested, but we would try
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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by matthijskooijman on Tue Mar 12, 2019 8:15 am

Thanks for the schematic. Looks like a good aproach. Using a transistor rather than the current diode also has the advantage of having a lower voltage drop when running on the battery, which should make it run a little longer on the battery as well. When running off 5V USB, the extra drop isn't really relevant. AFAICS, this should indeed fix the 6mA current when the ESP is powered down or deepsleeping.

However, I do think the problem might not be 100% fixed (though probably already sufficiently). When the CP2104 is powered on while the ESP is powered off, the current design uses around 6mA. AFAIU this is not just the power usage of the CP2104 chip (whose idle current is a lot lower), but I suspect that the CP2104 is keeping some pin powered, while the powered-down ESP draws current from there (though I haven't quite figured out what route this current takes exactly). This problem is fixed by making sure that the CP2104 is powered down when USB is unplugged.

However, I can see two cases that are still not perfect:
  1. When USB is plugged and the ESP sleeps, the same 6mA will be leaked. Usually USB has plenty of power available, but this might not be the case when using e.g. a powerbank to power a project.
  2. When the ESP is powered on but the CP2104 is sleeping, there *might* be a similar leakage going the other way (e.g. the ESP keeping a pin powered and the CP2104 leaking current). I'm not sure if this actually happens, though. Because this is only the case when the ESP is running and thus draws a lot more current, this problem is more tricky to measure, but also less of a problem (since adding a few mA to the running current of the ESP has a lot less impact).

To really fix this problems, the conductive path between both chips should be cut when either of them is powered down. However, this is probably not an easy thing to do, requiring a lot of components. Given the limited impact of both problems, it's *probably* fine to leave them unsolved (if they exist at all), but I wanted to at least mention them.

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by adafruit2 on Tue Mar 12, 2019 12:54 pm

before, we had the CP2104 powered from the 3.3V regulator which means that when disabled, the converter would go off. however, this made the CP2104 very unhappy, especially when the regulator got power before the VBUS rose (or something like that, can't remember) and the chip would pop. you can see many threads of people who destroyed their boards. if you're powering over USB, we will just have to deal with the CP2104 being on :)

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by MCHayek5 on Sat Jun 22, 2019 4:37 pm

Hello,
It's pretty difficult to remove cp2104 to cut traces for a modification.
I may try, but risk wrecking the pads.
I'd like to upgrade my Feather Huzzah's to Rev. F.
Are these available yet, and how can I confirm while ordering that Rev. F will ship?
Thanks,
Matt

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by matthijskooijman on Sat Jun 22, 2019 5:10 pm

It's pretty difficult to remove cp2104 to cut traces for a modification.

I think you can cut the trace next to the chip without having to remove the chip itself, though it is a bit finnick to get it right. I was planning to test a modification where a trace is cut and a diode is added, but I haven't gotten around to testing this completely, let alone documenting it....

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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by MCHayek5 on Wed Jun 26, 2019 10:18 pm

Matt,

Upon closer examination, I discovered I have a Rev. E Feather.
I made one trace cut just under the regulator (U2 pin 1).
This wasn't too hard using a new sharp Xacto blade.
With this cut, I can power from the battery, and charge/program/monitor from USB.
And, my deepsleep current has improved from >6mA to about 500uA for the system.
I can not power from the USB without a battery, but this is alright since I plan to always have a battery connected.

Thanks!
Matt
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Re: Adafruit Feather HUZZAH ESP8266 Power Consume

by matthijskooijman on Thu Jun 27, 2019 6:24 am

MCHayek5 wrote:I made one trace cut just under the regulator (U2 pin 1).

Right, that was indeed the place where I cut the trace.


MCHayek5 wrote:I can not power from the USB without a battery, but this is alright since I plan to always have a battery connected.


I think you can make this work again by adding a diode from the USB-side of the (now separated) VBUS to the regulator side of VBUS (e.g. from C3 to D4, or C3 to the VBUS pin). Just in case you (or someone else) ever needs this anyway :-)

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