Distance of UART communication

Answer:

Question Is it possible to use UART serial communication without any external component upto 25 feet? How can higher distance be achieved?

Response Yes. This will be possible at lower baud rates. If longer communication is required, we can use the correct impedance termination at the receiver end. The resistor network will maintain the receiver logic to be around 2V and thus the distance can be much higher than 20 meters. The block diagram of the system is shown below. This system was implemented in PSoC1 and the hardware set up using a CY3210 Eval 1 kit is also shown below