Low Power USB On-The-Go for AVR
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Development of devices, used for connections to personal computers, has mainly been based on the use of the parallel port and serial port on the PC. These interface connections are large and they re being replaced by smaller and faster interfaces. The USB interface is standard on modern PC s, and the old interfaces are in most cases removed. New challenges for the hardware developers arise, when the easy and reliable serial port interface is no longer available and the only way to connect to the computer is through USB. A study of the possibilities of a USB connection to an AVR has been performed. The small cost RISC microprocessors developed by Atmel have been utilized in several different products all over the world. The USB market using AVR microprocessors is yet to be explored by the industry and new innovating ways to use the USB is described in this study. A new line of AVR microprocessors incorporates a USB OTG module as a peripheral to handle the fast speed of the USB 2.0 interface. The AT90USB1287 microprocessor was used in this assignment, where the possibility to use the MCU as a host to connect other USB devices to it, was investigated. A system case based on this commercially available microprocessor has been done, where a USB On-The-Go interface has been realized. The development was done using the USB Key evaluation kit available from Atmel, with the AT90USB1287 microprocessor on board. Using this, a Mass Storage host was created. The firmware written for this application contains a file system driver using the Microsoft standard FAT file system. A memory card interface driver and protocol stack was also implemented to enable the user to connect to variable sized memory.