[Hangshun Training Camp] 485 communication display instrument-340465A

This is my first time using a 32-bit microcontroller. I hope I can implement a common function while learning and practicing at the same time.

Predictive features:

• For some models of instruments, Pv value reading and display
• RS485 interface/ModBusRTU protocol
• With over-limit alarm (relay/buzzer)
• Dimming
• 220V power supply

Non-target functions:

• Differential ADC test (cancelled)
• PWM output

Main material pre-selection:

• Main control: HK32F030MF4P6 with issue price <1 yuan
• Power supply: Linear transformer
• Alarm: 9V relay
• Communication: Maxim’s 485 chip serves as the communication interface
• Display: TM1650 is used as the display driver, and the 0.52 common cathode digital tube is used as the display (please pay attention to the pin position)
• Input: Touch the switch as input.

Problems encountered:

• [ ] I don’t understand USART’s RS485 DE hardware management function, and I don’t know how to configure the pins (I can’t find which pin can be configured as RTS)
• [x] Almost forgot to leave the debugging interface
• [ ] I have never used differential ADC and I don’t know how to deal with it.
• [ ] ------------------21/3/28----------------------------- ----------
• [x] The current input occupies the programming port and cannot be programmed. This function will not be tested. Solution without welding
• [x] There is no routine for I2C, and it took three nights to send something out.
• [x] 485 characters are incomplete during communication. Use a logic analyzer to find that 485 was forced into receiving mode before sending.

Some functional tests:

• The circuit welding is completed and the power-on temperature is normal.
• Classic introduction: light up an LED and learn about the use of GPIO firmware library
• Buzzer: Learned about the use of beep firmware library and learned to initialize peripherals. Using the internal low-speed oscillator buzzer, the measured frequency is 3.565KHz
• Button reading: use two buttons to control the buzzer switch
• Digital tube display: Use hardware I2C to successfully light up the digital tube, but the driver chip does not have an address. It feels like it is troublesome to use the firmware library. ----------------2021/3/29------------------------------
• Serial port transceiver: The routine is running. The most important thing is to delay the transmission, otherwise the 485 will change to the receiving mode before the 485 is sent.