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jules
17th August 2010, 14:33
Type K Thermocouple Shield for the Amicus18
Jules V. Jenson


This shield is based upon the Maxim™ Max6675 Cold-Junction-Compensated K-Thermocouple -to-Digital Converter (0°C to +1024°C). It needs no calibration and from 0 to +700 degrees Centigrade exhibits thermocouple accuracy.

This is not a low cost solution. This converter is quite expensive. One to twenty-four pricing at Farnell is £14.00. However it does the job and is quite easy to use.

The shield has two LEDs, one of which is used to indicate an open thermocouple condition. A Microchip™ MCP9791A Temperature sensor is on the board as well. Communication with the processor is via an SPI interface.

The code is continually executes a loop via a 57600 baud serial connection which outputs the on-board temp sensor’s calculated temperature, the measured sensor voltage, andADRESH AND ADRESL in hex format. It then reads the converter, checks the received value for an open thermocouple condition, then outputs the converter value in hex format and the calculated temperature of the thermocouple.

The Isis design, Ares Layout, and the cadcam files are available on request.