I'm building those 3D printed wristbands with an arduino connected to a NRF24L01 Transceiver module. It will be powered by a lipo cell with 160mAh and based on 3.3V operating power. The shells snap together with magnets. Those 4 switches are for chosing the channel you send and the bottom LED shows your own heartbeat. For now I start with a fingerclip with IR Leds to read the heartbeat. The missing parts are long ordered and for the contest I will create two working modules.
This could also be used for lasertag games, showing you the pulse of your team members and once they are "dead" they won't show anymore.
It has been 2 months now since I have ordered the cheaper heart rate sensor and unfortunately it got lost on its way here. Additionally I ordered around the Chinese National Day and I lost track of the time so now I'm overdue on my buyer protection. So I'm hoping that they will resend the sensor as soon as they read my reply today.
Some thoughts on the software, I think it will be a good idea to measure the time between pulses and send the value over the NRF24L01s and not the value of the analog read outs. Some what a bicycle computer for your heart. While writing that I just thought of connecting this project with the Open-Bicycle-Computer. Let's monitor the pulse of the bikes rotation and show the heart rate on the bicycle computer!
I'm going to order another heart rate sensor from a different seller to make sure I get one.
don't feed or order them at night. So the boards for the shield came in today and I placed all the parts facing towards the arduino board instead and missed connecting almost everything with vcc. It's all connected with each other, but not with vcc :D Luckily I can fix this with a jumper wire and turn everything upside down, put the dip switches on top of the smd resistors. I'm missing pin connectors to try complete the shield, so i'm ordering these and keep it in the box until arrival.. Normally I love those purple boards, but the leds and blue dip switches are hurting my eyes.
First things first - I can send data the way I want. Yay!
The bracelet is about 95% the same from the movie. It is missing those 4 dip switches, but is instead hard wired to channel 1 and I had to imrpovise about the leds. I don"t have a pulse sensor, but it would definately work as a prop the way it is right now.
As nothing ever is really done, I will get back to this after the contest.
Today my printrbot simple broke down on me, the hotend won't heat anymore - so there will be only one wristband. Meh. And I don"t have the arduino pro minis yet nor the leds so I had to improvise on the wristband. So backup strategy now will be round leds, one wristband, fake data from 2 breadboarded arduinos.
Having a slow day at work I decided to work on the pin settings and a test sketch for this set up. It really is only a blown-up blink sketch with inputs. While it does not sound like much, this is something I normally do on putting it together, realizing I failed too remember that I can't place those leds on the SPI and so on...
[updated] I integrated the code bits of the rf24 library and wrote some bits for the channel selection by the dip switch.