I'm tasked with a design/proof of concept for electrical side of fitness equipment. The main problem for me how to transfer the statistics from the fitness equipment to various consumer devices- iPhones/iPads/Android phones/PC's etc. The controller will probably be Arduino, at least for the initial prototype.

What I have come up with:

  • Use BlueGiga's BLE112 (as outlined here http://www.glynstore.com/bluegiga-ble112-bluetooth-low-energy-module/) for interfacing iPhone 4S+, iPad3, latest Macs and some of the latest Android devices.
  • Use some regular Arduino BT shield for communication with pretty much all other phones, except < iPhone4s (which don't have Bluetooth LE stack). Our company does not want to participate in Made For iPhone program in order to be able to communicate with < iPhone4S.
  • Use either Arduino Ethernet together with WiFi router packaged in fitness equipment OR use Arduino WiFi shield in adhoc mode, to communicate with < iPhone4s.

All of this seems an overkill- I could just use Arduino WiFi shield in adhoc mode, and that would probably cover all the other use cases (except for devices without wifi), however, I really don't like that device won't have access to the internet when connected to our equipment via wifi.

I have also explored using phones cellular data connection, but that would require internet access on the fitness equipment, which some might find weird.

I'm wondering if there are some other wireless ways of communication which I have overlooked. We would like to maintain a wide range of supported devices.


@RussellMcMahon hardware "dongle" would require participation in Made For iPhone program, wouldn't it? I'm also skeptic about communication via headphone jack- it just seems plain wrong for me.

@m.Alin Currently I'm looking for 1:1 communication between consumer device and our equipment, but keeping an option to connect the equipment to the internet would be nice.

  • \$\begingroup\$ Are you willing to have a low cost piece of hardware connect to the phone to give it wireless capability? This could free up your options substantially. Connection via USB to the "dongle" from the phone then allows almost any sort o suitable coms from dingle to exercise equipment. eg RF in many forms, IR, ultrasonic, NFC, ... . \$\endgroup\$
    – Russell McMahon
    Commented Apr 18, 2012 at 14:03
  • \$\begingroup\$ @fest how to transfer the statistics from the fitness equipment to various consumer devices So do you want a 1-to-1 communication between an equipment and a client's device? Or do you want a centralized communication between all the equipment and a device/server? \$\endgroup\$
    – m.Alin
    Commented Apr 18, 2012 at 15:08
  • \$\begingroup\$ @fest - I don't know enough about the 4s to be sure of the answer but I'd hope that they were not so insane as to close USB access to the extent that you could not write to and read from any USB device without their benison. If you can then you can make an interface. If you can't then they are very confident of their powers indeed. \$\endgroup\$
    – Russell McMahon
    Commented Apr 19, 2012 at 1:10
  • \$\begingroup\$ Let's try to remain objective about the problem, rather than arguing about the merits and demerits of the platform. Comments deleted. \$\endgroup\$ Commented Apr 19, 2012 at 1:17
  • \$\begingroup\$ @RussellMcMahon if by USB access you mean a device connected to Apple's proprietary hardware port, then that requires participation in Made For iPhone program to be allowed to use the port in your devices. \$\endgroup\$
    – fest
    Commented Apr 19, 2012 at 8:09

2 Answers 2


You could transfer the data over the microphone part of the microphone/headphone port present in almost all of these phones. Project HiJack provides an introduction to these methods. Most of these solutions transfer the data with Bell 202 modulation. There’s even a $79 development kit available.

It doesn’t sound like you need to actually power your equipment through the headphone jack.

You may also be familiar with the Square card reader. The older versions were passive and simply hooked up a cassette tape head to the microphone connection through a resistor, i.e. analog transfer. I believe the newer versions have a battery and a microcontroller and may also use Bell 202 or similar modulation.

  • \$\begingroup\$ I'm specifically looking for wireless solutions. \$\endgroup\$
    – fest
    Commented May 23, 2012 at 21:00

I have actually settled on a solution, which is quite close but not exactly one of proposed solutions in OP. I designed and successfully tested a prototype of Arduino shield that among application specific hardware also hosts Carambola embedded Linux module which is used for WiFi communication.

The module is relatively inexpensive (22 euro) for what it provides. I'm only using it's serial port for communication with MCU and wifi in access point mode- HTTP server running on it serves as a transport mechanism. The only downside for me was the need to come up with 12V->3.3V switching regulator to power the module.


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