Sunday, January 6, 2013

Generic Updates for January 2013

I’d like to thank all the visitors to the blog so far. So what to expect in the new year.

1) V3 Power Meter – I’m a little off track due to the holidays and sorting out the averaging issue, but I’m getting back at to it soon. This weekend I’ll be sorting out ANT+ not updating consistently issue. I haven’t talked about this much, but as it stands sometimes it’s calculating everything but not updating the ANT+ transmission.

2) BT 2.0 to ANT+ Bridge – I’m received a little criticism but I’m going to carry ahead to see if it works. I think I have a voltage mismatch so I’ll have to sort that potentially if the BT module won’t run on 3.3V. It lists 3.6v to 6v, so I suspect it won’t run. The ANT+ module needs 3.3 and I don’t think will survive much beyond that. If this works out maybe I’ll look at making a schematic for the BT and AP2 Modules. Possibly set it up for individual usage or maybe

3) nRF51422 development – This might be a little longer in the works. I’ve been holding off on ordering the EK or the DK kits until the new year. Now that it’s the New Year I’ll get around to it soon.

4) V4? This will be a long way off, but I’m currently envisioning an nRF51422 with ADS1247 ADC and a simple digital SPI/I2C interfaced gyro. Continuous updates.

So what else is new, more after the break:

I was informed with some new details regarding Nordic Semiconductors forthcoming BTLE / ANT+ combination chip. It does both BTLE and ANT+…. at the same time. That’ll be quite something! I believe Stages Stage One does both simultaneously, this means that it’s competitors will be able to jump into the BTLE market too.

This is great for the market, though not as great for ANT+. While the nRF51822 BTLE chip and the nRF51422 ANT+ chip are pin compatible (requires re-coding I believe for the different stacks) this raises an interesting question. Will this mean the lagging BTLE eats into ANT+ market share? Will more people use cell phones biking? I don’t know, but I feel a little bad as the ANT+ did a lot of the heavy lifting in unifying the wireless communications for bikes.

ANT-duino? I’ve been conversing with a fellow “hacker” (hopefully he doesn’t mind me referring to him as that) and has suggested something like an Arduino but using the nRF51422. This is kind of akin to the AP2 modules that already have FCC certification. The idea would be a multipurpose small board (Teensy 2.0 style) with the nRF51 series chips. I like this idea but unless I tailor V4 to use this I feel I might not get around to it.

Personally I’m debating between ordering the DK (Development Kit) or the EK (Evaluation Kit) for the nRF51 series. The DK “requires” the nRFgo development board, but it generally doesn’t use anything on this board at all. It’s more for power and interfacing to their development environment. In fact, to program it, it comes with two Segger J-Link OEM modules. So really, if I just got the DK I’d have two nRF51422 dev boards, one with a trace and one with an SMA antenna, two programmers which I could use on custom boards, and sample chips! The EK is great value at 100 dollars but I get one battery powered board with an on-board programmer that is too large for the power meter application. I’d just have to run wires into the headers

Open-source workouts – Some people may be familiar with my trainer software from my old site ( I’ve taken a lot of the workouts from Training and Racing With a Power Meter (2nd ed) and converted them into the format that I use for my software. There is limitations however, namely only power is the goal. It can’t do targets for heart rate, average power over a certain time, total average power, speed, etc. It can have targets for Cadence though, but this feels more like a secondary target to the power. I’m thinking about creating a CSV open source format that would incorporate more advanced features. I’ve love some feedback on this concept. Email me

On to the Crazy ideas! WOOO

DIY VO2MAX Setup… over… you guessed it, ANT+!!!! Imagine doing your own VO2max tests at home with your desktop computer, cell phone, or cycle computer (Garmin, maybe another firmware update on the edge 500 please?). There are O2 and CO2 sensors. Potentially either could be used to measure O2 uptake. You’d need two of either. I haven’t done a lot of research on this but you’d have one on the intake to your lungs measuring O2 of the atmosphere, and one on the outlet measuring O2 exiting the lungs. The masks I believe have one way valves. This could be done with CO2 as I believe you’d still reach saturation on the outlet at VO2 max, so rather than watching O2 levels decrease to a plateau you would watch CO2 increase to a plateau.

Golf / Tennis power meter – not ANT+, but use the same tech to measure the force that the use hits the ball with along with the velocity via an accelerometer and gyro. It'd need a Kalman filter to get the approximate velocity. The math might be a bit harder than the power meter because of the free swing nature.

Driveshaft power meter – Again a reuse! Two guys at work have offered up their cars for me to implement this. 350z and a 230 Mercedes. Could be interesting, though I think transmitting data from under a metal car might be hard. I’ve heard of this in industry for race cars.


  1. On the tennis racket, you are welcome to pursue an idea that I had a while back. Tennis is both strength and technique bound. Force is important, but there is a sweet spot in the mesh where it is important for athletes to hit the ball. Some form of tension sensor or doppler sensors to identify the location of the ball on the mesh would be informative. A visualization (heat map) at the end of a training or match session may reveal how one's form degrades with fatigue.

    I'm enjoying reading about this project with the crank power meter.

    1. Not being a tennis play this is some interesting information. Determining a heat map might possibly be able to be done with some clever strain arrangement. I hadn't even thought about that. It'll sit in the back of my head waiting to get out. Thanks!