Micropython Firmware for DIN Rail Energy Monitor (ATM90E26/ATM90E36 and any future boards)

Micropython code to run on the DIN rail dual ATM90E26 module.

• Web Front End from @john_newall. Works on both ESP32 and ESP8266, better on ESP32 due to better RAM and CPU resources. Please read John's excellent article on web design with limited resources.

• Micropython Energy Monitor inspiration from @shenki. His presentation at PyconAU2017 inspired me to make this port and dive into the wonderful world of Python on microcontrollers, FPGA's and everything else.

---

Setup

If you would like to build your own micropython image please follow the ESP32 micropython instructions here or download a pre-built one here. Windows Subsystem for Linux, Babun or a VM is recommended for building on Windows.

The micropython packages can be baked in using instructions here:

• ../unix/micropython -m upip install -p modules picoweb
• ../unix/micropython -m upip install -p modules micropython-logging
• ../unix/micropython -m upip install -p modules utemplate
• ../unix/micropython -m upip install -p modules micropython-btreedb
• ../unix/micropython -m upip install -p modules micropython-btree

After firmware is built push it onto the ESP32 as below (I did not add my user to dialout, hence the sudo):

• sudo esptool.py --port /dev/ttyS10 write_flash -z 0x1000 build/firmware.bin

Loading Micropython code

For best performance this code uses a custom micropython image which can be obtained here. This image has picoweb and a few modules frozen to minimise runtime RAM footprint. Flash this image and copy over the required Python, HTML, CSS and JS files for the web application using the serial thunking approach developed by mpy-utils. The mpy-fuse is particularly useful for copying over the large selection of files which form this project. On Windows Subsystem for Linux mpy-sync is a viable but slower alternative for copying files via terminal. A sample mpy-sync command is shown below:

sudo mpy-sync --port /dev/ttyS10 DIN_Wemos_ATM90E26_upy/

NOTE: For mpy-sync to work it needs to access the REPL, ensure any running code is stopped and the ESP32 is in REPL mode before attempting to sync code

Running

The code base is composed of multiple runnable python files. The main.py is designed to get basic functionality going, additional experiments can be performed by pressing Ctrl+C in the micropython console and switching to another main function.

IoT Servers

The sample code here is targeted to self-hosted Graphite. Recommended method for installing and running with all the dependencies in place is a docker image on Linux and Vagrant on Windows. Alternative IoT data hosts are:

• AWS IoT
• EmonCMS
• Thingspeak
• Blynk
• and many many more ....