# CircuitPython BLE Heart Rate Zone Trainer Display ## Overview https://youtu.be/1j6aqB6q6_4 Heart rate zone training can be an excellent way to monitor workout intensity and increase your fitness and endurance. By spending certain periods of workout time at different percentages of your maximum heart rate. For example, warming up at 50-60%, then entering the "fitness zone" of 60-70% for a period, then going into the aerobic zone of 70-80%, finally peaking in the intense anaerobic zone of 80-90%. Using a Bluetooth LE heart rate monitor armband or chest strap, you can send up-to-the moment heart rate data to a battery-powered Feather nRF5280 Bluefruit equipped with a pair of seven segment LED displays. Place it on a wall or shelf where you can easily see it while you work out! Or carry it or hook it to your bike. CircuitPython makes it straightforward to connect to your heart rate monitor and stream the heart rate data and zone percentages to the displays. ## Parts & Materials ## Heart Rate Monitor You'll need a heart rate monitor that supports Bluetooth Low Energy (BLE). I'm using the [Scosche RHYTHM+](https://www.scosche.com/rhythm-plus-heart-rate-monitor-armband) but you should be able to use any monitor that uses the Bluetooth SIG Heart Rate service standard. These work by flashing green (and sometimes yellow) LEDs against your skin and then measuring the reflected light that returns. The color changes/darkens during the pulse of your heart thanks to all that blood sloshing around! ![circuitpython_rhythm-color-band_config_1000.jpg](https://cdn-learn.adafruit.com/assets/assets/000/087/965/medium640/circuitpython_rhythm-color-band_config_1000.jpg?1580514257) ### Adafruit Feather nRF52840 Express [Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062) The **Adafruit Feather nRF52840 Express** is the new Feather family member with Bluetooth® Low Energy and _native USB support_ featuring the nRF52840!  It's our take on an 'all-in-one' Arduino-compatible + Bluetooth® Low Energy with built-in USB... Out of Stock [Buy Now](https://www.adafruit.com/product/4062) [Related Guides to the Product](https://learn.adafruit.com/products/4062/guides) ![Angled shot of a Adafruit Feather nRF52840 Express. ](https://cdn-shop.adafruit.com/640x480/4062-02.jpg) ### FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers [FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers](https://www.adafruit.com/product/3417) This is the **FeatherWing Tripler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are three! The magic of the Tripler comes when you want to connect your Feather to... In Stock [Buy Now](https://www.adafruit.com/product/3417) [Related Guides to the Product](https://learn.adafruit.com/products/3417/guides) ![Triple prototyping feather wing PCB with socket headers installed](https://cdn-shop.adafruit.com/640x480/3417-05.jpg) ### Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Red [Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Red](https://www.adafruit.com/product/3108) One segment? No way dude! 7-Segments for life! This is the **Red Adafruit 0.56" 4-Digit 7-Segment Display w/ FeatherWing Combo Pack**! We also have these combo packs in [Green](https://www.adafruit.com/products/3107), In Stock [Buy Now](https://www.adafruit.com/product/3108) [Related Guides to the Product](https://learn.adafruit.com/products/3108/guides) ![Angled shot of a rectangular shaped 7-segment breakout board with an LED matrix soldered on.](https://cdn-shop.adafruit.com/640x480/3108-02.jpg) ### Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Blue [Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Blue](https://www.adafruit.com/product/3106) One segment? No way dude! 7-Segments for life! This is the **Blue Adafruit 0.56" 4-Digit 7-Segment Display w/ FeatherWing Combo Pack**! We also have these combo packs in [Green](https://www.adafruit.com/products/3107), In Stock [Buy Now](https://www.adafruit.com/product/3106) [Related Guides to the Product](https://learn.adafruit.com/products/3106/guides) ![Angled shot of a rectangular shaped 7-segment breakout board with an LED matrix soldered on.](https://cdn-shop.adafruit.com/640x480/3106-01.jpg) ### Lithium Ion Polymer Battery - 3.7v 1200mAh [Lithium Ion Polymer Battery - 3.7v 1200mAh](https://www.adafruit.com/product/258) Lithium-ion polymer (also known as 'lipo' or 'lipoly') batteries are thin, light, and powerful. The output ranges from 4.2V when completely charged to 3.7V. This battery has a capacity of 1200mAh for a total of about 4.5 Wh. If you need a larger battery, Out of Stock [Buy Now](https://www.adafruit.com/product/258) [Related Guides to the Product](https://learn.adafruit.com/products/258/guides) ![Lithium Ion Polymer Battery 3.7v 1200mAh with JST 2-PH connector](https://cdn-shop.adafruit.com/640x480/258-02.jpg) ### Part: USB Cable quantity: 1 USB A to Micro-B - 3 foot long [USB Cable](https://www.adafruit.com/product/592) ## Optional Seven Segment LED displays look pretty good on their own, but they look even better with a colored gel filter in front of them! I really like the way they look through a small piece of [LEE Filters CL797 Gel Filter Sheet - Deep Purple](http://www.leefilters.com/lighting/colour-details.html#797&filter=cf). I get mine from [Filmtools](https://www.filmtools.com/leegelsheet718.html). ![](https://cdn-learn.adafruit.com/assets/assets/000/087/916/medium800/circuitpython_hrt_build_0585.jpg?1580495202) ## Alt Version You can build a CLUE variant of this project instead. All you'll need are a CLUE board instead of the Feather and seven segment displays. ### Adafruit CLUE - nRF52840 Express with Bluetooth® LE [Adafruit CLUE - nRF52840 Express with Bluetooth® LE](https://www.adafruit.com/product/4500) Do you feel like you just don't have a CLUE? Well, we can help with that - get a CLUE here at Adafruit by picking up this sensor-packed development board. We wanted to build some projects that have a small screen and a lot of sensors. To make it compatible with existing projects, we made... In Stock [Buy Now](https://www.adafruit.com/product/4500) [Related Guides to the Product](https://learn.adafruit.com/products/4500/guides) ![Animated GIF showing CLUE board displaying data from the many on-board sensors.](https://cdn-shop.adafruit.com/product-videos/640x480/4500-04.jpg) - [Next Page](https://learn.adafruit.com/circuitpython-ble-heart-rate-monitor-gizmo/understanding-ble.md) ## Featured Products ### Adafruit Feather nRF52840 Express [Adafruit Feather nRF52840 Express](https://www.adafruit.com/product/4062) The **Adafruit Feather nRF52840 Express** is the new Feather family member with Bluetooth® Low Energy and _native USB support_ featuring the nRF52840!  It's our take on an 'all-in-one' Arduino-compatible + Bluetooth® Low Energy with built-in USB... Out of Stock [Buy Now](https://www.adafruit.com/product/4062) [Related Guides to the Product](https://learn.adafruit.com/products/4062/guides) ### FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers [FeatherWing Tripler Mini Kit - Prototyping Add-on For Feathers](https://www.adafruit.com/product/3417) This is the **FeatherWing Tripler** - a prototyping add-on and more for all Feather boards. This is similar to our [FeatherWing Proto](https://www.adafruit.com/products/2884) except there are three! The magic of the Tripler comes when you want to connect your Feather to... In Stock [Buy Now](https://www.adafruit.com/product/3417) [Related Guides to the Product](https://learn.adafruit.com/products/3417/guides) ### Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display [Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display](https://www.adafruit.com/product/3140) One segment? No way dude! 7-Segments for life! This is the  **Adafruit 0.56" 4-Digit 7-Segment Display w/ FeatherWing Combo Pack**! We have these combo packs in [Green](https://www.adafruit.com/products/3107),  Out of Stock [Buy Now](https://www.adafruit.com/product/3140) [Related Guides to the Product](https://learn.adafruit.com/products/3140/guides) ### Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Red [Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Red](https://www.adafruit.com/product/3108) One segment? No way dude! 7-Segments for life! This is the **Red Adafruit 0.56" 4-Digit 7-Segment Display w/ FeatherWing Combo Pack**! We also have these combo packs in [Green](https://www.adafruit.com/products/3107), In Stock [Buy Now](https://www.adafruit.com/product/3108) [Related Guides to the Product](https://learn.adafruit.com/products/3108/guides) ### Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Blue [Adafruit 0.56" 4-Digit 7-Segment FeatherWing Display - Blue](https://www.adafruit.com/product/3106) One segment? No way dude! 7-Segments for life! This is the **Blue Adafruit 0.56" 4-Digit 7-Segment Display w/ FeatherWing Combo Pack**! We also have these combo packs in [Green](https://www.adafruit.com/products/3107), In Stock [Buy Now](https://www.adafruit.com/product/3106) [Related Guides to the Product](https://learn.adafruit.com/products/3106/guides) ### Adafruit 4-Digit 7-Segment LED Matrix Display FeatherWing [Adafruit 4-Digit 7-Segment LED Matrix Display FeatherWing](https://www.adafruit.com/product/3088) One segment? No way dude! 7-Segments for life! A Feather board without ambition is a Feather board without FeatherWings! This is the  **Adafruit 4-Digit 7-Segment LED Matrix Display FeatherWing**! This 7-segment FeatherWing backpack makes it really easy to add... In Stock [Buy Now](https://www.adafruit.com/product/3088) [Related Guides to the Product](https://learn.adafruit.com/products/3088/guides) ### Red 7-segment clock display - 0.56" digit height [Red 7-segment clock display - 0.56" digit height](https://www.adafruit.com/product/865) Design a clock, timer or counter into your next project using our pretty 4-digit seven-segment display. These bright crisp displays are good for adding numeric output. Besides the four 7-segments, there are decimal points on each digit and an extra wire for colon-dots in the center (good for... In Stock [Buy Now](https://www.adafruit.com/product/865) [Related Guides to the Product](https://learn.adafruit.com/products/865/guides) ### Blue 7-segment clock display - 0.56" digit height [Blue 7-segment clock display - 0.56" digit height](https://www.adafruit.com/product/812) Design a clock, timer or counter into your next project using our pretty 4-digit seven-segment display. These bright crisp displays are good for adding numeric output. Besides the four 7-segments, there are decimal points on each digit and an extra wire for colon-dots in the center (good for... In Stock [Buy Now](https://www.adafruit.com/product/812) [Related Guides to the Product](https://learn.adafruit.com/products/812/guides) ## Related Guides - [Introducing the Adafruit nRF52840 Feather](https://learn.adafruit.com/introducing-the-adafruit-nrf52840-feather.md) - [Introducing Adafruit CLUE](https://learn.adafruit.com/adafruit-clue.md) - [Using the Bluefruit Dashboard with Web Bluetooth in Chrome](https://learn.adafruit.com/bluefruit-dashboard-web-bluetooth-chrome.md) - [No-Touch Hand Wash Timer for Circuit Playground Express and CLUE](https://learn.adafruit.com/no-touch-hand-wash-timer-for-cpx-and-clue.md) - [Adafruit 7-Segment LED FeatherWings](https://learn.adafruit.com/adafruit-7-segment-led-featherwings.md) - [RP2040 RunCPM Emulator with USB Keyboard & HDMI screen](https://learn.adafruit.com/rp2040-runcpm-emulator-with-usb-keyboard-hdmi-screen.md) - [CLUE case](https://learn.adafruit.com/clue-case.md) - [Garmin Lidar Lite Range Finder](https://learn.adafruit.com/garmin-lidar-lite-range-finder.md) - [CircuitPython BLE Morse Code Chat](https://learn.adafruit.com/circuitpython-ble-wireless-morse-code-chat.md) - [Arcade Synth Controller](https://learn.adafruit.com/arcade-synth-controller.md) - [BLE Synth with the Feather nRF52840 and Circuit Playground Bluefruit](https://learn.adafruit.com/ble-synth-with-the-feather-nrf52840-and-circuit-playground-bluefruit.md) - [CircuitPython Servo Tester](https://learn.adafruit.com/circuitpython-servo-tester.md) - [Creative Inspiration Activity Generator](https://learn.adafruit.com/creative-inspiration-activity-generator.md) - [Pulse Oximeter Wireless Data Logger](https://learn.adafruit.com/pulse-oximeter-wireless-data-logger.md) - [Bluetooth LE Sensor Nodes to Raspberry Pi WiFi Bridge](https://learn.adafruit.com/bluetooth-le-broadcastnet-sensor-node-raspberry-pi-wifi-bridge.md) - [Welcome to CircuitPython!](https://learn.adafruit.com/welcome-to-circuitpython.md) - [CLUE Step Counter](https://learn.adafruit.com/clue-step-counter-st-lsm6ds33.md)