Nixie tube clock system based on the Internet of Things

B station video display: [IoT Nixie tube clock](https://b23.tv/gIcZlZN)
1. System overall framework design
  The main function of this design is that the MCU connects to wifi through the Tuya module (WIFI module) to obtain local weather information and use it to calibrate the system clock. The temperature and humidity of the surrounding environment are obtained through the temperature and humidity chip SHT30, and uploaded to the server through the Tuya module. The MCU processes the time information generated by the internal RTC clock and lights up the Nixie tube to display the time information through the driver chip HV57708. A 1.3-inch LCD color screen displays weather information and settings and other human-machine interfaces, and is controlled by three touch buttons.
2. System hardware design
2.1 The main control chip
  uses STMicroelectronics' STM32F103CBT6 as the main control chip. The initial design used C8T6, and later it was changed to CBT6 because the font and picture parameters exceeded 64k. There is no difference between the two chips except for the memory size (in fact, the memory is the same, but C8T6 is not detected after 64k when it leaves the factory, which may cause problems). It is tested that C8T6 can be used directly. It can be downloaded directly in KEIL using STlink and work normally (the C8T6 I use here is from LiChuang Mall and is guaranteed to be authentic. It is not clear whether some merchants on tb are feasible).
2.2 Driving
  Circuit The Nixie tube driver chip is HV57708. HV57708 is a serial input to parallel output driver chip that can withstand high voltage and can complete the function of 4-way input to 64-way output. Here we refer to the clever solution of netizens. It is known that the maximum voltage supported by HV57708 is 90V, and the minimum voltage maintained by the Nixie tube is 145V. Here, a 75V voltage regulator diode is used to input a 75V voltage to HV57708. When HV57708 outputs a high level of 75V, the voltage between the Nixie tube pin and the anode is less than 100V and cannot be ignited. When HV57708 outputs a low level of 0V, the voltage between the Nixie tube pin and the anode is 170V, and the Nixie tube lights up.
2.3 Power module
  The power comes from a 12V power adapter. To meet the needs of other devices, the 12V is stabilized to 5V using the DCDC chip LM2596S-5.0 and then stabilized to 3.3V using the AMS1117. The 12V is boosted to 170V using the MAX1771.
2.4 WIFI module
  The WIFI module uses the Tuya Smart IOT wb3s module and is connected to the microcontroller using UART.
2.6 Temperature and humidity module
  The temperature and humidity module uses sht30. Use IIC to connect to the microcontroller.
2.7 EEPROM
  Since some data needs to be saved when the power is off, AT24C02 is used in this project to connect to the microcontroller through IIC to store data.
3. System Software Design
(This is a very sad news. On August 25, I planned to start writing the software design part, but I found that I had deleted the last code project when I was organizing the materials . Nearly two

weeks of work was wasted . Hard disks have value , but data is priceless ! ... TIM3_IRQHandler(void)//Timer 3 interrupt service routine { if (TIM_GetITStatus(TIM3, TIM_IT_Update) != RESET) { LCD_Scan();//Screen refresh HGG_Display();//Nixie tube display TIM_ClearITPendingBit(TIM3, TIM_IT_Update ); } } ``` As shown in the above code, the system work is divided into three parts, namely the main loop, 20ms timer 2 and 100ms timer 3. The main loop processes the data received by the Tuya module serial port; Timer 2 executes functions that require fast speed and are not easy to be blocked, such as buttons, controls and Nixie tube refresh functions; Timer 3 does not need to execute so fast, but there are functions like screen refresh, which will be blocked for a short time. Therefore, in terms of priority, Timer 2>Timer 3>Main loop.   You can download the code project to see how each function completes the corresponding work. The comments are very clear. 4. Shell design The shell is drawn using soilworks. The source file and STL file are placed in the attached model. The source file can be modified or directly printed using the STL file. The actual project is printed on 3D Monkey. The smaller aperture can be used normally. You can watch the video on station B for assembly. There is a disassembly screen. 5. Function implementation and results Normal display status: ![Download (3).jpg] Non-nixie tube display time period: ![Download (1).jpg] Weather display: ![Download (2).jpg] Configuration interface: ![Download.jpg] **The open source design has a screen panel, which is printed using the Jiali Chuang panel as the front cover of the design. The dimensions in the design are measured and there is no problem. You can modify it to your favorite pattern. Order link: [Li Chuang Mall Panel Printing](https://dos.szlcsc.com/). ** **Order parameter selection: ** Printing material: Black translucent Printing method: Front material thickness: 1mm
















































Material size: 200×300mm
3M adhesive: The required
light shielding degree, both regular and strong light shielding can be used

Panel printing effect:
![IMG_20221025_130541.jpg]