The XR21V1410 is a single channel 3.3V USB UART compliant with the USB 2.0 Full-Speed specifications. Up to six of the modem control signals per UART channel can be used as General Purpose I/O, or GPIO, pins. The XR21V1412 is a two channel version of the XR21V1410; therefore it can have up to twelve GPIOs. Similarly, the XR21V1414 is a four channel USB UART and can have up to twenty four GPIO pins. The XR21V141x USB UART products have an I²C interface where an I²C EEPROM can be used to specify various USB parameters such as a custom Vendor ID (VID), Product ID (PID), remote wake-up support, bus-powered or self-powered mode, and maximum USB power. The core logic and UARTs run from the internal 48 MHz oscillator.