USB TWI is an example application using Objective Development's firmware-only USB driver for Atmel's AVR microcontrollers. This project describes the realizzation of a device that through the PC USB interface allows to acquire data from the peripheral of a microcontroller and also by TWI (Two Wire Interface, I2C derivative technologies) sensors. USB TWI provides a simple interface at same microcontroller peripherals. So you can use GPIO, ADC and TWI easy in your own PC application. Objective Development's USB driver is a firmware-only implementation of the USB 1.1 standard on cheap single chip microcomputers of Atmel's AVR series. It implements the standard to the point where useful applications can be implemented. The firmware requires avr-gcc and avr-libc package. Examples of applications are;

• USBStepper: it drive a stepper motor trought a TMC222 integrated circuit is been developped to explain how this device could be used. USBDataLogger is an example application using USB-TWI device;
• USBDataLogger: it can be read temperature from same 2-wire temperature sensors, like the MCP9800, and read the microcontroller's analog input. The acquired data can be recorded on a file (CSV format) with a minimum time step of 2 seconds.