NZ5000: software and hardware PC interface for heart rate monitors


It does what the $800+ Polar heart rate monitors & interfaces do: gives realtime pulse display, flashes on each systole and downloads and analyzes the data in realtime, saving it in an ASCII file to be read by graphing or other programs.

The unit converts pulse data from heart rate monitors such as the Cat Eye PL-5000 into serial data which can be saved in flash memory or on a disk and then analyzed and graphed on a PC. The serial data may be output to a laptop, palmtop or one of the units designed for embedded systems such as the i386EX, which has a built-in serial port and is about 3" x 3" x 0.25" (7.6 x 7.6 x 0.6 cm).

For connection to a PL-5000, the hardware portion of the interface can be easily constructed at home with a soldering iron and a few inexpensive parts that may not even need to be purchased if one already has them "lying around". Or the hardware can be mailed along with the software; please specify what kind of serial connector is required (e.g. DB-9, DB-25, proprietary, etc.)

The unit was designed for cycling but can be used for any athletic activity, or for measuring resting heart rate, even during sleep.

The software consists of an 880-byte executable which performs the logging and display functions, plus two other programs, each about 70 KB, for graphing and analysis. VGA or better display recommended but not required.

Sample of output:

Graph of a resting pulse log: (Click here)
Report file: (Click here)

(This log from July 17th, 1997 from 3:28 to 9:53 a.m. shows the resting pulse drop into the 30's during sleep; for verification I measured my pulse over several ten-second and one-minute intervals manually while I was awake. The lowest my heart rate got while awake was 39 bpm.)

Report file from July 18th, 1997, the day before I did the bike tour of Massachusetts and Pennsylvania (Boston-Hillside 1997) for which I have a trip diary elsewhere in this website: (Click here for report file). This was when I recorded my lowest resting heart rate (36 bpm). Graph of a bicycle ride log: (Click here: self-executing)
Report file: (Click here)

(the current version has many more features than that in these samples.)

The log of the July 4th, 1997 ride includes a significant amount of time after the ride itself, showing the settling of the pulse rate afterwards and causing the average heart rate to drop to the 90's.

Custom interfaces can also be designed for other earlobe pulse sensors and some chest-mount sensors; please e-mail for further information. It is recommended that you verify that you have a compatible hardware configuration before ordering anything. The logging software is priced at US $25.00, and the analysis and graphing software is also US $25.00.

Click here if you are interested!
First posted: July 4, 1997. Last updated: Mar. 10, 2003.

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For the legal beagles:

Cat Eye is a registered trademark of Tsuyama/Cat Eye, Osaka, Japan.

i386EX is a trademark of Intel.

Other trademarks and registered trademarks belong to their respective owners, i.e. Polar, NZ-5000.