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4 port USB thermometer
USBTherm is a simple USB device based on the AVRUSB project, more specifically the hid-data project.
It is intended for monitoring server room and air-conditioning temperatures but could of course be used for any temperature monitoring.
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USBTherm allows up to 4 thermistors to be connected to it to and it logs the temperatures from these to a file on the
host PC. The device uses RJ45 sockets for the thermistor connectors, allowing you to use existing cabling to position thermistors
around the room or building.
This page is not intended as a guide for building a USBTherm (just look at the hid-data example and add some thermistors in),
rather it is merely here as a location for firmware and documentation.
Thermistors are connected to pins 2 and 6 in an RJ45 plug [todo - picture].
The device uses KTY81-121 positive correlated thermistors. Alternative thermistors can be used but if their characteristics differ a great deal from
the KTY81-121, 4 internal resistors may require changing. The precision is about 0.4 degrees C, and the range is -15 to 80 degrees. Distance over
cat5 has a small effect but this can be accounted for on the host computer.
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