A brief interlude

This won’t be a trip to the lobby but rather a reflection on the state of sports sensors. If you don’t want to read all of this the short is this: How come we don’t use a Bluetooth SPP and connect it directly to an AP2 module to build an ANT+ to Bluetooth bridge. It’d cost about 60+ dollars and your phone can talk to ANT+ without modifications.
Currently I have to say that as for interoperable sensors go I think Ant+ is the first time I’ve ever seen anything do better than this xkcd comic about standards. I think the biggest fiasco of it I seen was when NVidia decided to create MXM, a laptop graphics card. They built the standard, opened it to everyone, had ATI (at the time) review it and they gave them back revisions! And then what happened… Well several things happened but suffice to say it didn’t really catch on.
I think that with companies like Look and Polar being very against Ant+ they have made a decision to limit their own market share. At at least that’s how I want to see it, but it’s not the whole truth.
Look wants to go to Bluetooth LE for their KEO power meter, but there is no power meter profile and currently there is already interoperability issues for heart rate monitors using Bluetooth (but I haven’t seen it first hand) that I’ve heard of. Update: DCrainmaker has noted decent interoperability recently with the new LE devices.
Originally I picked up a Garmin FR60 so I could get a heart rate monitor and a ANT+ usb stick cheap. Each device on their own was 50 dollars, but I got the FR60, the stick, the HRM, and the foot pod shipped for 165. For and additional 50 dollars I purchased the bike sensor. This was all to gear up to make my “virtual coach” software which, while poorly written and buggy, I’ve used for the last year. When it became apparent that other people where doing the same and realizing my limited coding ability I decided to revive my strain gauge work and develop this power meter.
This is where things fall apart in terms of standards compatibility. ANT+ is great, but it’s not in phones, tablets, laptops, etc. What is common in these happens to be Bluetooth – we can thank all those hilarious looking people walking around with Bluetooth earpieces and the advent of AD2P for high quality audio in cars.
However, more and more people want to use their phones. I argued against running with my “free” phone, because out of contract it’s a minimum of 600 dollars to replace. That's right, most decent smart phones are 600+ dollars if not on a contract! My laptop didn’t cost that much! However, as I’ve gained faith in my Samsung product I’ve ditched my iPod Nano and now run with the phone. I still think my argument for getting a sensor based watch or GPS watch is valid - durability, price, weight, etc. Even the highest end models are not 600 dollars and are way more robust then a fragile smartphone. Plus my FR60 lasted a year on a single coin cell.
However, whenever I’ve met with anyone about these things the first question is usually revolving around can it be connected to their cell phone. The short answer is “likely not”.
If you have an old iPhone you could buy an adapter, now you have to buy and adapter to plug into another adapter and I haven’t heard for certain if it will work (ANT+ to 30pin, 30pin to lighting). On the Android front it’s worse as the 30 pin apple connector had serial lines, but Android has micro-usb leaving the only option to use some sort of Android IOIO device.
There exists a Bluetooth profile called SPP, or serial port protocol. The AP2 can be hardwired to serial at a specific baud rate. I’m probably going to order one of these and see if I can bridge the AP2 to Bluetooth via serial port protocol. It means that you can have this device on you, or on your bike, or in your bike phone mount.
What’s the downside. Power consumption. This is my nemesis most recently, as it’s an important aspect for the consumer market but many compromises have to be made to achieve it. Bluetooth 2.0 has the SPP profile but LE does not. That means it’s a bit more power hungry. Unfortunately I don’t know how hungry, but it’s worth the 20-30 dollars to get a Bluetooth SPP modem to find out.