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Minimum Mass Wireless Coupled Scanning Voltmeter
Near Field Communications (NFC)
A 10 bit scanning voltmeter with a Minimum Mass Wireless Coupler, based on the ATMega8.Range to the Minimum Mass Base Unit is 10 to 15 cm. If the voltmeter is battery operated, it can be floated from ground.


The basic Minimum Mass Wireless Coupler technology is described and links to other projects on this site that use the Minimum Mass Wireless Coupler are located on the web page, Minimum Mass Wireless Coupler.

Downloads
Download the AVRStudio assembly source for the program: vlfvmtrmg8.asm
Download the AVRStudio assembly source for the include file: vlfcwm8.inc



Schematic of the 4 channel scanning voltmeter. The layout isn't
critical. The 33 uH choke is reduce noise from the controller's
VCC pin on the analog reference voltage.

This project is very simple physically, intended to demonstrate how easily the Minimum Mass RF Link can be added to a project. The circuit shown does not have a lot if the nice things that I would usually include in an instrument, such as the ability to handle out-of-range input signals without the circuit suffering damage. Therefore, I suggest that if you build this as a stand-alone instrument, that you add protection crcuitry to the inputs.

The power suuply is the reference voltage in this case, and the binary-to-decimal conversion assumes that the refernce voltage is +5 volts, so I sugges that an adjustable regulator be used to obtain a precise +5 volts. You could use three alkaline cells (for example) in series, but the calibration would be way off.

The A/D converter setup and binary-to-decmial conversion routines were taken from the Low Cost Telemetry Device project  on this site. The firmware was created by taking the Low Cost Telemetry Device firmware, removing the un-needed code, and adding calls to the Minimum Mass Wireless Coupler drivers instead of to the USART routines.


External link:
Two students at Cornell University incorporated some of these concepts in their school project. The project as posted at the university website is very complete and very well written.
A Remote Controlled DMM With Minimum Mass Wireless Coupler

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Contents ©2005 Richard Cappels All Rights Reserved. http://www.projects.cappels.org/

First posted in March, 2005

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(Summary: No warranties, use these pages at your own risk. You may use the information provided here for personal and educational purposes but you may not republish or use this information for any commercial purpose without explicit permission.) I neither express nor imply any warranty for the quality, fitness for any particular purpose or  user, or freedom from patents or other restrictions on the rights of use of any software, firmware, hardware, design, service,information, or advice provided, mentioned,or made reference to in these pages. By utilizing or relying on software, firmware, hardware, design, service,information, or advice provided, mentioned, or made reference to in these pages, the user takes responsibility to assume all risk and associated with said activity and hold Richard Cappels harmless in the event of any loss or expense associated with said activity. The contents of this web site, unless otherwise noted, is copyrighted by Richard Cappels. Use of information presented on this site for personal, nonprofit educational and noncommercial use is encouraged, but unless explicitly stated with respect to particular material, the material itself may not be republished or used directly for commercial purposes. For the purposes of this notice, copying binary data resulting from program files, including assembly source code and object (hex) files into semiconductor memories for personal, nonprofit educational or other noncommercial use is not considered republishing. Entities desiring to use any material published in this pages for commercial purposes should contact the respective copyright holder(s).