JeVois Smart Embedded Machine Vision Toolkit
The hardware serial port (UART port) on your JeVois smart camera is TTL-level (not RS-232 levels) and supports both 3.3V and 5V logic.
The logic voltage to use is supplied by the connected microcontroller to the smart camera (RED wire, IOREF voltage. This voltage should be provided by your micro-controller and should be the voltage at which your RX and TX signals operate). Arduino boards provide the IOREF pin for this purpose. Thus, a 5V Arduino will output 5V to IOREF, and will use 5V levels for RX and TX. In contrast, a 3.3V Arduino will output 3.3V to IOREF and will use 3.3V levels for RX and TX.
To connect to an Arduino board, you would typically do as follows: