Hi, We are looking to have an easy hardware interface for plugin to an Iphone. We have a sensor that measures the heart pulse rate. The goal is to "adjust" this low frequency pulse to an appropriate signal similar to the signal magnitude of a microphone. Presently I have no idea what signal magnitude comes out of a microphone (standard Apple Iphone ear phone with microphone) that is plugged into the Iphone - and I have no idea which poles of the 4-mini Jack poles one needs to use, and what needs to be done that the Iphone recognizes a plugged in tool as a microphone... Several questions that need to be found out and answered by an expert as you are.
There is a free Iphone (also available for Android) app called "60beat" - and if you just plugin the Iphone headset and tap a pulse onto the microphone (or make a voice rhythm with "popping"), the app will recognize the pulse and shows the rate. Your job would be to use our sensor with 3V square signal and "adjust" it to microphone magnitude - and make sure that our sensor will be recognized by the Iphone as a microphone.
What we know by now is, that we could use the standard microphone, tap on the microphone and the software does recognize this signal. We need someone who is able to provide a very simple way of damping the 3V peak to peak rectangle signal to a signal that is similar to the microphone signal.
Your job is to provide a detailled hardware plan of this interface with wiring plan with which we can use our sensor unit and plug it in to an Iphone, as follows:
EXISTING SENSOR WITH 3 CONNECTORS (GND, VCC-3V, SIGNAL-OUTPUT) - Power supply by battery
>>>> YOUR INTERFACE with Mini-Jack (4-poles)
The steps of the project involve (as you proposed):
1)Theoretical work--------------IEEE papers
3)Component selection----------Digikey, mouser
6)Manufacturing and building board------manufacture company
7)Prototype test------------Labotary equipment
8.)Sending the prototype to Switzerland for testing
For the project we will send our hardware to you. At the end of the project you send the the prototype and our hardware back to Switzerland.
Project fee would be 200 USD – with a 100USD milestone, which will be release when you provide a photo with the hardware prototype and schematic design.
After receiving the prototype here in Switzerland, we will test the prototype and if everything is ok, we will release the final milestone of 100USD.
1 freelancer is bidding on average $200 for this job
This is not a bid, it is a technical information note only. We are members of MFI Apple Program and involved in iPhone/iPad accessories design and are open for collaboration with you on any projects. Regards, Stephan