Smart Home Audio(325)


Old Thermostats use monochromatic LCD or LED solutions. In the past, the price of color LCD module was unattainable. However, as demand increased, production increased, and prices gradually approached civilianization, which in turn the display screens of home appliances gradually becoming color LCD module. The color LCD module can make the status display of temperature, weather, and humidity more user-friendly, and can make more interactive effects, including timer switches, settings, etc. can have more amazing performance.

Specifications of true color thermostat:

  • The requirement of chroma is true color 18-bit or 24-bit : the meticulous display of chroma will affect the performance of graphic colors, and then affect the user's perception.
  • It is necessary to use the protocol MODBUS RTU to control the surroundings such as temperature switches and temperature sensors through the RS485 interface.
  • Smooth touch panel screen : smoothness of control will affect user satisfaction
  • Graphic control interface process: Provide a convenient design user interface, which can save the time of product entering mass production

Nuvoton Technology ’s new true color temperature controller reference design provides a complete of solutions, starting from the hardware design, using the graphics control series N9H20 microprocessor, and built-in 32 MB SDRAM memory, reducing hardware Design difficulties, the built-in large-capacity memory brings three major benefits:

First, the circuit and PCB design are very simple, and the PCB area is reduced.

Second, reduce external high-speed signals, greatly reduce Electro Magnetic Interference (EMI), and easily pass FCC / CE / BSMI / CCC tests.

Third, using LQFP package, it is easy to debug and maintain.

This solution provides a complete hardware circuit design, and PCB layout. In software design, a complete graphic of the temperature controller is provided, which includes the power-on screen show, three-page slide mode switching, temperature display, temperature control, perpetual calendar, backlight control, and RS485 control. The software uses open source , so that users can change the process and pictures according to their own plans, and users can directly download and use related pictures.

TFT Thermostat-1

TFT Thermostat-2


Reference design specifications

CPU N9H20K51N : Arm926EJ-S 200MHz, Build-in 32 MB SDRAM
LCD 4” 480x480 18bit, Capacitive Touch
Storage 1 Gb NAND Flash
Input /output RS485 Port x 1, RS232 x1
Power USB 5V In ( 340 mA )



Thermostat Reference Design User Manual

Thermostat HMI Gerber & Schematic PCB File

Thermostat HMI example code

Thermostat HMI Github



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