EEMON42

ESP32-C3-based 42-channel home energy monitor using the Analog Device ADE7816 emergy monitor chip

Features

42 Current monitoring inputs with 3.5 mm jacks for current transformers
Single board, 10x10 cm design with OLED screen with a OLED/switch/rotary encoder user interface
Two AC voltage for split phase voltage monitoring and board powering
Micropython control software with MQTT telemetry streamed over WiFi

Status

V0 Hardware - Board is built. - Hardware validation: - Switcher works. Board can be powered via USB or AC jacks. - Can operate the ESP32 via the USB and micropython. - All buttons work. - OLED display works - Only one ADE7816 is populated so far, but we can read registers. - Todo: - Check analog inputs of ADE7816. Populate rest of the board. Calibrate all inputs.

Software - Building basic micropyton modules - Todo: - Implement main loop and monitoring/GUI tasks as coroutines. Improve display functions. Integrate with Home Assistant.

Design Details:

Accurate Energy monitoring performed by seven ADE7816
- ESP32-C3 controller implemented with a Espressif ESP32-C3-WROOM-02 or AI Thinker ESP-C3-13 module, providing
  - Single core RISC-V 160 MHz processor
  - 4 MB flash
  - Wifi, Bluetooth
  - Embedded USB controller
- 96x64 pixel, 0.96" OLED display
- 3 pushbutton keys
- Rotary encoder with integrated push button
- Dual 9-15VAC inputs for line voltage monitoring and powering the board
- Micro-USB connector for UART programming and JTAG debugging, and alternate board powering
- Integrated DC-DC converter for wide input voltage range

Rationale

The EEMON42 was developed as personal project for learning all the steps to build an embedded controller project from A to Z, starting from from schematics & layout, online PCB manufacturing, hand soldering of high density SMD devices, an developing the embedded controller software. More specifically, this includes:

Learn KiCAD 6.0 and learn to place and route designs
Use PCBWay or JLCPCB to manufacture the PCB
Learn SMD soldering techniques for sizes down to 0603 and QFN 0.5mm pitch devices
Learn the internal architecture of the ESP32-C3-based module
Software development tools (Visual Studio Code / Platform IO / ESP IDF/ Micropython etc)

History

2022/06: Design start 2022/12: Board was manufactured by PCBJLC. Board is assembled. Preliminary hardware verification is performed: power, ESP32, buttons and OLED display works with Micropython. Discovered bug in esptool that prevent the flashing stub to operate when USB-enabled micropython has booted first. 2023/03: ADE7816 is installed. Successful communication with it. Implement Python object for it. Implement SPI object to handle SPI CS pins shared with buttons and pin interrupts.

Known bugs & gotcha's:

v1 hardware:

GPIO9 can be pull down and prevent micropython boot if encoder is left in mid-position
Missing GPIO2 & GPIO8 pullup (but still works without those)
A reset swwitch would be nice, but is becoming les and less necessary as hardware matures
A power LED would prevent accidental soldering on a powered board...
Pad and copper pour cleareaces too small close to USB connector: rookie solderers might cause shorts when applying too much solder...
serial number chip (or some GPIO strapping) might be useful for software to identify the hardware automatically. rev2 GPIOs assignments will change.
encoder is a bit too close to screen for big fingers. Buttons should be spread out more.
Find socket with proper height for screen.

Changelog:

v2 hardware (in development):

OLED CS7 is now on FSPICS0 for native hardware-enabled CS toggling (if possible)
Encoder Button CS2 is on GPIO9 to prevent unwanted boot mode and allow user-controlled to force downnloader boot (although USB interface does not need it except for esptool bug)
CS0 and CS1 moved to other GPIOs
Added weak pullups on GPIO2 and GPIO8 to be sure

danodus / EMON36