Lowest power (battery compatible) breakout board for LoRa and ESP32 or ARM processors

Dear TTN-fellows,

I’ve searched a lot for the most efficient lora boards that consume let’s say below 100µA in deep sleep and also read carefull through this topic:

However, when I have tried the TTGO or Heltec boards, I’ve had deep sleep currents of 12mA or 2mA respectively.

Here are the two boards that I have tried:

  1. TTGO LoRa v1.0 an v2.1 with ESP32
    https://www.banggood.com/2Pcs-LILYGO-TTGO-ESP32-SX1276-LoRa-868MHz-bluetooth-WI-FI-Lora-Internet-Antenna-Development-Board-p-1295045.html?rmmds=search&cur_warehouse=CN

  2. Heltec with ESP32:
    https://www.amazon.de/MakerHawk-Entwicklungs-Brett-0-96inch-Anzeige-kompatibles/dp/B076P8GRWV/ref=sr_1_15?__mk_de_DE=ÅMÅŽÕÑ&dchild=1&keywords=esp32+lora&qid=1598547777&s=computers&sr=1-15

This one seems super interesting to me:
3. Heltec cubecell with arm processor:
https://www.amazon.de/LoRaWAN-Entwicklungsboard-ASR6501-Consumption-Intelligent-siehe-abbildung/dp/B07ZH7NL38/ref=psdc_1626220031_t3_B07HF1V2G8

So probably it has all been discussed but the big ESP32 & SX127X topic doesn’t give makers a clear advise on what are really the best boards to use atm.
So I hope this thread will still be useful.

Those sound more like “failure to enter sleep” current readings.

The ESP32 has fairly limited and awkward suspend capabilities compared to a true MCU. Almost any ARM Cortex part will be more flexible than an ESP32 or ESP8266 in this regard.

However, just having the right chip isn’t enough - there are 1000 ways to get low power hardware and software design wrong, any of which will cause a failure to achieve your goal. Many boards have been fabbed with just one little mistake which costs a few hundred out-of-spec microamps, and cannot be fixed without a respin. Meanwhile various software bugs can cause things to stay awake when they should sleep.

Thinks to watch out for:

  • Oscillators left running, especially TCXO’s
  • Signals asserted against pulling resistors
  • Signals driven to powered off peripherals, which end up trying to run off the I/O in place of the missing supply
  • Debug interface connections donating or stealing power
  • Getting stuck in a non-sleep software state
  • Peripheral chips not configured to low power state
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Yup, low power ain’t easy. But it is possible. In this case, using an STM32.

Robust, memory- and power-efficient system layer, programmable via USB using the Arduino IDE. So easy to use and 2 uA sleep current.

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You may have missed this:

Above post also mentions Heltec CubeCell, which is further detailed in its own topic:

Heltec CubeCell - part 1
Heltec CubeCell - part 2

Currently I’m using an Adafruit Feather M0 with RFM95 LoRa radio and needed to get it into deep sleep to preserve battery life. Unfortunately the best I could do with the stock Adafruit Feather board was to get a sleep current of about 80uA. My approach to resolve the issue was to develop a extremely low power Feather Wing board to control power to the device I was able to reduce sleep current to 16uA and in some configurations 220nA. Greatly expanding my battery life.

The Feather Wing I designed, includes a very low power RTC and a 6 axis accelerometer. Together these devices can switch power to the Feather M0 board on a time or 6D/4D orientation change or motion detection event.

Perhaps a similar approach is possible for your design.

Have you shared this design anywhere?

Additional details on the design of the PowerMiser FeatherWing can be found at
https://origtech.com/Products/PowerMiserFeatherWing.html

I designed a board that gets 1.6uA in deep sleep.

https://www.thethingsnetwork.org/forum/t/smart-garden-project-complete-with-mobile-app/

But until you either start selling it or share the design, that doesn’t help the OP

True. @ecosoph do you have any other requirements other than low power consumption? If you are looking for a solar recharging dev kit, I would caution against using LiPo for unattended, outdoor applications. At a minimum, you’ll want to monitor battery temperature to ensure you are not charging outside of spec.