About the Device
Can I buy one?
No, sorry… not yet. This past year has been a research and design phase and the product has been submitted for patent approval.
Does it really work?
Absolutely. Check out the videos section for clips of it in action
How does it work?
It’s fairly complicated, but essentially the device plugs in the bottom of the iPod (dock connector) and uses a microcontroller to tell the iPod what to do. The microcontroller samples two sensors, an ECG or an Accelerometer, and calculates the frequency from the users heart rate or jogging speed. Once calculated, the microcontroller will then command the ipod to switch to a playlist containing songs matching that BPM.
During a workout, these statistics (heart rate, time, current song) are being recorded in the device and are transferred to a computer via usb when the device is synced. In the BPMsync application, you can plot your heart rate or running speed over time and view what songs were played during each section. You can also save and compare previous workouts and share them with friends.
How do you command the iPod?
The iPod is controlled with an interface known as AiR (Apple iPod Remote) via the Apple Accessory Protocol. AiR is what is used in higher end cars to control iPods from steering wheels and to display songs on the dashboard. Its a RS-232 protocol 8N1 and gives great functionality of the device. For more information about Air or the Apple Accessory Protocol, please visit the iPodLinux website.
How is the heart rate calculated?
Originally we planned on using a method called Photoplethysmography which is an optical way of detecting a users heart rate. You shine an IR led through a thin piece of skin and read the reflection. As the heart pumps blood in and out of the cells, they become darker and lighter. After testing this in the lab, it was very difficult to get a clean signal on a user who was moving around, so we decided to use a wireless ECG chestband.
What Microcontroller are you using?
Texas Instruments MSP430F2272 with the IAR C Programming environment and the EZ430 USB programmer. The microcontrollers are free samples from ti.com, the software is free, and the programmer was $20
About Capstone
What is capstone?
Capstone is a Senior Design Project competition designed by Northeastern University. 20 teams competed in the Electrical and Computer Engineering department to create a new device that encompasses what was learned over your entire college career.
How much money were you given?
Each group is given a budget of $500 to $1000 dollars. Purchases are paid out of pocket and reimbursed by the school right before graduation. We used every last dollar of the $1000 budget which included the cost of 3 board designs, digikey orders for various parts, a POLAR wireless chestband and receiver, and an iPod Nano.
Other Questions?
Contact me and I’ll post them