Low Power ESP8266 – Sleeping at 78 micro Amps

I recently bumped into NodeMCU firmware for the ESP8266. It’s an Lua interpreter, making tinkering with IoT ideas really simple. Just flash the firmware onto the ESP8266 and connect via serial console. You can start prototyping right away using the interactive Lua interpreter. You can easily persist your ideas on a simple flash file system.

print(wifi.sta.getip())
--nil
wifi.setmode(wifi.STATION)
wifi.sta.config("SSID","password")
print(wifi.sta.getip())
--192.168.13.101

For convenient development, there is ESPlorer, a basic IDE for Lua on the NodeMCU. It allows you to develop the Lua scripts locally and then save them to the MCU via serial protocol.
ESPlorer

To make developing with the ESP-01 module easier, I created a basic development board. It provides easier access to the individual pins, has jumpers for flashing mode (GPIO00) and enable (CH_PD), offers a button for reset, and also integrates a socket for a step-down power supply.
ESP8266 (ESP-01) dev board top-view ESP8266 (ESP-01) dev board side-view
ESP8266 (ESP-01) dev board front-view ESP8266 Development Board

Although NodeMCU provides access to the deep-sleep mode of the ESP8266

node.dsleep(microSecs);

this is not available straight away on the ESP-01 module, as the ‘post-sleep-reset-pin’ XPD_DCDC (8) of the MCU is not connected to the reset pin. I solved this by manually soldering a single wire of a stranded cable between the reset pin of the module and the XPD_DCDC (8) pin of the MCU (bottom right corner of the mcu in the first photo). On top of this, I also removed the red power LED by simply prying it off with a tiny screw driver.
With these two modifications, the module is able to make use of the deep-sleep mode and successfully resets and restarts after waking.

During deep sleep the module now uses just 78 microAmps! On two normal AA batteries with 2600mAh, that’s good for well over 3 years!

Update 2015-04-12:

Due to frequent questions about the Fritzing file or schematics, I uploaded the Fritzing file:
ESP-01_ESP8266_Board.fzz
(if the file extension gets mixed up, apply .fzz manually)

Update 2015-11-18:

Marv Marvelous over at http://blog.grafovision.sk/ translated this article into Slovak. Thanks Marv!

55 thoughts on “Low Power ESP8266 – Sleeping at 78 micro Amps

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