What had to be solved
The task was to create a hardware and firmware platform for automating ventilation equipment, local setup and integration with external dispatching systems.
Projects / Industrial automation and embedded control
HVAC equipment controller
Embedded controller for HVAC equipment: measurement channels, analog outputs, relay control, local display, Modbus RTU and an Ethernet-ready hardware/software base.
What the project reached
A working HVAC controller platform was developed with local operator control, industrial communication interfaces and a prepared base for further network development.
Project materials
Photos and working materials
Engineering context
Important constraints
The controller works with analog and discrete inputs and outputs.
A local operator interface on the built-in display had to be readable and serviceable.
The interface is controlled by an encoder and a button, including service and debugging screens.
Two independent isolated Modbus RTU channels were required.
Settings have to be saved between restarts.
Work done
What was included
Firmware for STM32F407.
Graphical interface on LVGL.
Modbus RTU exchange in Master and Slave modes.
Settings storage in external flash memory.
RTC with backup battery.
Ethernet bring-up on LAN8720A.
Details
Engineering project description
Implemented functions
- embedded GUI on the local display
- encoder and button control
- display of measured parameters and states
- analog and discrete inputs and outputs
- relay and analog-output control
- two independent Modbus RTU Master/Slave channels
- settings storage in external flash memory
- RTC with battery backup
- Ethernet bring-up on LAN8720A
- service and debug screens for diagnostics
Technology base
The project uses STM32F407, C / STM32 HAL, LVGL, Modbus RTU, external flash memory and RTC with VBAT. Ethernet bring-up on LAN8720A was performed separately: PHY operation, RMII clocking, link, receive and transmit were confirmed.
Operator interface
The embedded interface includes a main screen, debug screen and service sections. It is designed for navigation with an encoder and a button, including short and long presses, menu navigation and visible display of operating parameters.
Further development
The working plan still includes a PC tool for adding user algorithms, Modbus TCP and tests on real objects.
Contact
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