5584

Controller with ESP32-S3 for demand controlled ventilation system with 12 valves and 16 sensors and LCD display

This project is intended as a replacement of the Itho demandflow controller. The reason that this project was started because my controller at home was behaving strange, the transformer and fuse failed and it is expensive to replace. With modern microcontrollers it should be relatively easy to make a controller for such a system. This project is inspired by the orignal Itho controller but not intended to be an exact copy of the Itho controller.

The basis for this design is:

  • Speed of Itho fan can be controlled by either MQTT or HTTP API with settings Low, Medium and High
  • The controller has 12 channels for 12 Itho valves of type DemandFlow Klep (545-7100). The interface is identical.
  • This controller can be a 1:1 replacement
  • The system must be modular, e.g. it is not required to add the display, a different RTC could be used, the number of sensors can be
  • The software must be open source
  • The hardware must be open source
The hardware design is based on common electronic parts. The basis of the design:

  • Microcontroller ESP32-S3 or ESP32. The design is with the ESP32-S3 soldered on the board but one could also choose to install an ESP32 microcontroller through the 30-pin interface
  • 74HC595 for multiplication of processor I/O. Each valve has 4 coils to control and therefore 4 outputs are required per valve. In total 48 outputs are required. The 74HC595 are divided in two groups enabling scaling down to 6 valves for smaller houses
  • I2C interface for: 
    • up to 16 sensors
    • Display (4x20 characters LCD with I2C backpack)
    • Realtime Clock
  • Use of two I2C busses, Wire and Wire1: 
    • Wire: Bus 0 sensors and LCD
    • Wire1: Bus1 sensors and RTC
  • Connection to sensors through I2C multiplexer (TCA...) enabling the use of I2C sensors with fixed I2C addresses
  • Addressable RGB LEDs for status
  • Accurate RTC with battery backup because most actions are time based
  • Single 15V power supply with on-board 3.3V and 5V convertors (1A capacity each)
  • Operation of sensors on 5V or 3.3V. Data communication always on 3.3V
  • MOSFET output drivers for low on state resistance. Alternatively ULN2803 could used as well (pin compatible)