MIKROE-2897 RS232 2 Click Mikroe MIKROE-2897 RS232 2 Click performs full RS232 to Universal Asynchronous Receiver-Transmitter (UART) signal conversion and allows both 3.3V and 5V operation. This click board features ±15kV Electrostatic Discharge (ESD) protection for the RS-232 I/O pins. Mikroe MIKROE-2897 Click features an onboard surface mount device (SMD) jumper that allows the user to select power supply voltages between 3.3V and 5V.