UART3和UART4无法通信

• ezreal

  Posts: 15

  Joined: 2024-03-10 6:01

  2024-04-04 7:52

  但我单独测试UART3/4的RX和TX，都可以正常接发数据。
  当时当我将UART3.TX连接UART4.RX，以及UART4.TX连接UART3.RX，如下图：
  

  

  

  使用以下代码测试（一开始尝试的是单线程版）：
  

  Code: Select all

  from periphery import Serial
  import threading
  import time
  
  def uart3_task():
      uart3 = Serial(
          "/dev/ttyS3",
          baudrate=115200,
          databits=8,
          parity="none",
          stopbits=1,
          xonxoff=False,
          rtscts=False,
      )
  
      # Send messages from UART3
      print("UART3 starts working!")
      msg = b"START, PLEASE!\n"
  
      while True:
          # Continuously send messages until response received from UART4
          uart3.write(msg)
          print(f"UART3 sent: {msg}!")
  
          time.sleep(0.5)  # Sleep for 1 second between messages
  
          # Check if response received from UART4
          buf = uart3.read(128, 1)  # Set timeout to 1 second
          print(f"UART3 receive: {buf}")
          if buf:
              data_string = buf.decode("utf-8").strip()
              if data_string == "Response from UART4!":
                  print("UART3 received response from UART4:", data_string)
                  break  # Break out of loop if response received
  
      uart3.close()
  
  def uart4_task():
      uart4 = Serial(
          "/dev/ttyS4",
          baudrate=115200,
          databits=8,
          parity="none",
          stopbits=1,
          xonxoff=False,
          rtscts=False,
      )
      print("UART4 starts working!")
      while True:
          # Wait for message from UART3
          buf = uart4.read(128, 5)  # Set timeout to 1 second
          print(f"UART4 received: {buf}")
          if buf:
              data_string = buf.decode("utf-8").strip()
              print("UART4 received:", data_string)
  
              # Send response from UART4
              uart4.write(b"Response from UART4!\n")
              print("UART4 sent: Response from UART4!")
  
      uart4.close()
  
  # Create and start threads for UART tasks
  thread_uart3 = threading.Thread(target=uart3_task)
  thread_uart4 = threading.Thread(target=uart4_task)
  
  thread_uart3.start()
  thread_uart4.start()
  
  # Wait for threads to finish
  thread_uart3.join()
  thread_uart4.join()
  

  输出日志如下：

  Code: Select all

  # python uart.py
  UART3 starts working!
  UART3 sent: b'START, PLEASE!\n'!
  UART4 starts working!
  UART3 receive: b''
  UART3 sent: b'START, PLEASE!\n'!
  UART3 receive: b''
  UART3 sent: b'START, PLEASE!\n'!
  UART3 receive: b''
  UART3 sent: b'START, PLEASE!\n'!
  UART4 received: b''
  UART3 receive: b''
  UART3 sent: b'START, PLEASE!\n'!
  UART3 receive: b''
  UART3 sent: b'START, PLEASE!\n'!
  UART3 receive: b''
  UART3 sent: b'START, PLEASE!\n'!
  UART4 received: b''
  

  可以看到，UART3/4都是正常的，但是无法接受数据。
  
  不知道这是什么原因？

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