怎么在同一引脚上连接TX和RX

大家好！我正在用PSoC 1 CY8C24123A做一个项目。硬件：我在PC -COM电缆上的软件-RS485到COMLATE（有最大的223（1设备）-最大值485（1设备））-CY8C24123A板（有SN75 176B……）。SN17176B的A、B信号与A、B信号最大值一致。（我使用RS485标准，波特率为19200）。通过UART用户模块实现PC与CY8C24123A之间的通信，但TX和RX连接到同一个PIN。PIN P0.4是TX和RX。我必须配置PIN 0.4。-P0.2控制SN75 176B发送或接收数据。P0.2＝1发送；P0.2＝0接收。内容：PC将发送数据到PSoC，之后PSoC将数据发送到PC。如果PSoC从PC接收3字节0xAA。PSOC发送0xAA、0x31、0x00到PC。如果PSoC从PC接收3字节0xBB。PSOC发送0xBB、0x33、0x00到PC。但是通信不好。有时，PC接收数据失败或不真实地接收数据。我想当我切换TX和RX在同一个引脚不好！你能告诉我解决这个问题的方法吗？多谢。下面是我的计划！
ADC16RS55V2.ZIP
251.5 K



     以下为原文
  Hi every body!
I'm doing a project with PSoC 1 CY8C24123A.
Hardware:
-My software on PC - COM cable - RS485 to COM circuit (have MAXIM232 (1 device)- MAXIM485(1 device)) - CY8C24123A board (have a SN75176B...).
A,B signal of SN75176B conect to A,B signal MAXIM485.
(I'm using RS485 standard, baudrate is 19200).
-Communication between PC and CY8C24123A via UART user module, but TX and RX connect to same pin.
-Pin P0.4 is TX and RX. I have to configure pin 0.4.
-P0.2 control SN75176B to transmit or receive data. P0.2 = 1 transmit; P0.2 = 0 receive.
Contents:
- PC will send data to PSoC, after that PSoC send data to PC.
-If PSoC received 3 bytes 0xAA from PC. After that  PSoC send 0xAA ,0x31, 0x00 to PC.
-If PSoC received 3 bytes 0xBB from PC. After that  PSoC send 0xBB ,0x33, 0x00 to PC.
But communication is not good.
Some times, PC received data fail or receive data not truely.
I think when I switch between TX and RX at the same pin not well!
Can you tell me solutions to solve that problem?
Many thanks.
Below is my project!
  

•   ADC_RS485_V2.zip 251.5 K