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Development of a full-fledged USB-interface for an existing microcontroller system

: Böhne, Bert
: Peter, Christian

Enschede, 2007, 71 pp.
Enschede, FH, Bachelor Thesis, 2007
Bachelor Thesis
Fraunhofer IGD ()
hardware; data interface; Device Interface

In the research project "EmotionsSensorik" of the Fraunhofer Institute for Computer Graphics in Rostock the objective is to determine the emotional condition of a human being. To do that, some physiological parameters have to be determined. Sensors are placed in a glove to measure the heart rate, skin conductivity and skin temperature. This data is sent to a mobile unit which can save it on a SD-Card or send it further to a PC via RS-232 (Com-Port). On the PC, advanced data analysis can be performed to determine the emotional condition.
The Com-Port is not longer a common port on today's PCs. It is counted to the so called "Legacy Ports". The new standard for serial communication is the Universal Serial Bus (USB). The USB brings faster speeds, plug and play, an extensible count of slots and more good features with it. In such a transitional period, existing products have to be changed or upgraded to support the new manner of communication. For the product of the Fraunhofer Institute this means that the mobile unit needs to be improved. The microprocessor which is used can communicate via RS-232 but is not applicable for USB. Redesign of the system with a new microcontroller which provides USB connectivity is not wanted. Therefore an USB to RS-232 bridge controller, a USB-Controller chip or a second microcontroller with the needed capabilities should be used. An USB to RS-232 bridge controller has already been added to the system for a quick solution. But this solution was not satisfying.
Hence in this bachelor thesis a full fledged USB communication is realized. A second microcontroller has been added to the system. The second microcontroller implements forwarding of RS-232 data via USB, updateability of it self and the possibility to read out the data of the SD-Card. Furthermore, to communicate with PC applications several existing drivers as well as a self-developed driver are used.