Heart rate monitor

A lightweight program to display the heart rate reading from a Bluetooth Low Energy device.

This has only been tested on a Polar H7 (non-referral link) but others should work.

Reportedly working devices include:

• Polar H7, Polar OH1, Polar 10
• Coospo HRM
• Magene H64

Requires Windows 8.1 or newer.

The executable and code are released under MIT license.

Code can be built using Visual Studio Community 2022.

Motivation

I owned a Polar H7 I could not get to work with any iOS software for use in the gym. I decided to repurpose it as a way to read my heartrate while I worked on the computer. I create my own due to lack of available software.

The program's secondary purpose is for Twitch streamers. After looking into streamer setups I saw an excessive mix of hardware and software was needed. I am not a Twitch streamer but I am willing to add the customizations needed by request.

Change log

1.7.4 May 3rd, 2022

• Include UDP output for IPC. (#35)

1.7.3 February 10th, 2022

• Drastic dependability improvements. Will retry more aggressively if the bluetooth device disconnects. (#25)
• Fixed quoting issues and incorrect column values in CSV output. (#27)

1.7.2 August 13th, 2021

• Added support for a heart rate file. A file that contains only the most present heart rate. (#25)
• Added file menus for adjusting csv, IBI, and heart rate file output.

1.7.1 December 29th, 2020

• Fixed font size in dialog not being what was entered. (#19)

1.7 November 30th, 2020

• Added text alignment option. (#17)
• Added window size being saved. (#17)
• Added font size and style selected in font dialog being used. (#17)
• Fixed a potential deadlock. (#17)

1.6 September 27th, 2020

• Added support for Energy Expended and RR-Intervals readings writing to logfile.
• Added support for IBI file output.
• Fixed logfiles containing date variables not working correctly.
• Fixed logfiles file access sharing, allowing proper real time reading of their contents.

1.5 June 13th, 2020

• Added background image support (#10)
• Made UI updates more responsive.
• Made context menu available from right clicking form, also.

1.4 April 27th, 2019 ·

• Added LogFile/LogFormat settings for writing BPM log to file.
• Added system tray context menu for selecting colors/fonts.
• Fixed (maybe?) the issue with the heart rate recording could stop.

How to use

1. Connect appropriate bluetooth device inside Window's bluetooth settings.
2. Download prebuilt binaries or build from source.
3. Run HeartRate.exe

I do not have the time to turn this into production grade software but I am willing to expand it to your needs. At startup, the program searches for an appropriate device and attempts to register a notification event for heart_rate_measurement. If this fails, the error is likely vague and not overly helpful. If you believe your device should work with this software but does not, please open a github issue with specifics.

This will not work for any general USB/bluetooth heart rate monitor. It has to be a Bluetooth Low Energy device supporting heart_rate_measurement.

By default, only an icon in the system tray is displayed. When the heart rate goes over an alert threshold, a balloon notification shows.

Clicking the system tray icon reveals a window with scaling text. This is for Twitch streamers to be able to region for broadcast.

Settings

Most settings are exposed in the UI through a context menu by right clicking the main window or the system tray icon. The rest can be accessed by editing the XML settings file directly.

Options not inside the UI Right clicking the system tray icon gives the option to edit an XML settings file. When the editor is closed, the settings will be reloaded automatically. The file is %appdata%\HeartRate\settings.xml

Setting	Type	Default	Description
Sizable	bool	true	If the window is a normal sizable window. false looks better but is not recognized by OBS as a window.
LogFormat	text	csv	The format to write to the LogFile. Only "csv" is valid.
LogDateFormat	text	OA	The format to write the date column as. See Datetime formatting.
LogFile	text	empty	The full path of where to write the logged data to. If empty, no file log is kept. A %date% token can be included to substitute in the date. A custom formatter can be included, such as %date:MM-dd-yyyy% Example: C:\users\joe\desktop\heartrate-%date%.csv
IBIFile	text	empty	The full path of where to write the IBI data to. Writes log of RR-Intervals in milliseconds in IBI supported file format. Supports date syntax like LogFile does.
HeartRateFile	text	empty	The full path of where to write the last heart rate to. Anything previously in the file is overwritten. Only the the most present heart rate will exist in the file. Supports date syntax like LogFile does.
AlertLevel	number	65	The heart rate to display a system tray notification balloon at. 0 to disable.
WarnLevel	number	70	The heart rate to use WarnColor at. 0 to disable.
AlertTimeout	number	120000	The amount of milliseconds to cooldown for being able to show an alert after one was shown.
DisconnectedTimeout	number	10000	The amount of milliseconds after disconnecting to await for a valid device connection before displaying "X"
UDP	host:port	empty	A UDP end point to write the "LogFile" output to. Format is ip:port, ie: <UDP>127.0.0.1:2115</UDP>

Settings also exposed by the UI

Setting	Type	Default	Description
FontName	text	Arial	The font name for the system tray icon.
UIFontName	text	Arial	The font name for the window display.
UIFontStyle	text	Regular	The font style for the window. Multiple styles can be specified by comma separation. Regular, Bold, Italic, Underline, Strikeout.
UITextAlignment	text	MiddleCenter	The alignment of the text in the UI. Can be TopLeft, TopCenter, TopRight, MiddleLeft, MiddleCenter, MiddleRight, BottomLeft, BottomCenter, BottomRight.
Color	color	FFADD8E6	The default color for the system tray icon.
WarnColor	color	FFFF0000	The system tray icon color once WarnLevel has been met.
UIColor	color	FF00008B	The default color for the window display.
UIWarnColor	color	FFFF0000	The window display color once WarnLevel has been met.
UIBackgroundColor	color	00FFFFFF	The background color for the window display.
UIBackgroundFile	text	empty	The full path of a background image.
UIBackgroundLayout	text	Stretch	The background image display layout. Possible values: None, Tile, Center, Stretch, and Zoom. More information.
UIFontUseSize	bool	false	Should the size in UIFontSize or selected from the Font dialog be used. If false, the font size scales automatically with the window.
UIFontSize	number	20	The size of the font if UIFontUseSize is true.
UIWindowSizeX/UIWindowSizeY	number	350/250	The saved window size. This is automatically saved when resizing.

color values are formatted as 32bit ARGB hex values. Leading 0's are optional.

Datetime formatting

Datetime formatting is done using the standard C# syntax. One special exception is "OA" which will convert to an "OLE Automation Date" formatted date, which is useful for Excel.

The default LogFile date formatter is yyyy-MM-dd hh-mm tt. The timestamp is taken at the startup time of the program.

Documents about standard and custom datetime formatters: https://docs.microsoft.com/en-us/dotnet/standard/base-types/custom-date-and-time-format-strings https://docs.microsoft.com/en-us/dotnet/standard/base-types/standard-date-and-time-format-strings

Notice on deployment

Some builds of Windows 10 have bug related to security which causes Desktop apps to stop receiving notification callbacks from GATT characteristics after receiving a few initial callbacks. More details available or in similar posts on social.msdn.microsoft.com.

There are several workarounds, the simplest being creating an AppId for the app in the Windows Registry and adding a security setting for the AppId, like below:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AppID\{C6BFD646-3DF0-4DE5-B7AF-5FFFACB844A5}]
"AccessPermission"=hex:01,00,04,80,9c,00,00,00,ac,00,00,00,00,00,00,00,14,00,\
  00,00,02,00,88,00,06,00,00,00,00,00,14,00,07,00,00,00,01,01,00,00,00,00,00,\
  05,0a,00,00,00,00,00,14,00,03,00,00,00,01,01,00,00,00,00,00,05,12,00,00,00,\
  00,00,18,00,07,00,00,00,01,02,00,00,00,00,00,05,20,00,00,00,20,02,00,00,00,\
  00,18,00,03,00,00,00,01,02,00,00,00,00,00,0f,02,00,00,00,01,00,00,00,00,00,\
  14,00,03,00,00,00,01,01,00,00,00,00,00,05,13,00,00,00,00,00,14,00,03,00,00,\
  00,01,01,00,00,00,00,00,05,14,00,00,00,01,02,00,00,00,00,00,05,20,00,00,00,\
  20,02,00,00,01,02,00,00,00,00,00,05,20,00,00,00,20,02,00,00

[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\AppID\YOURAPP.exe]
"AppID"="{C6BFD646-3DF0-4DE5-B7AF-5FFFACB844A5}"

Wanting to remain lightweight and not having an installer, this is not handled automatically by the program.

Icon Credit

Heart icon made by Paomedia.