To use CardioTrainer's pedometer feature, you can use the "Treadmill Walking" or "Treadmill Running" exercise types.
NOTE: If you're recording a workout with an exercise type that uses GPS, CardioTrainer will use the pedometer until it has found a GPS signal. Once it has that GPS signal, it won't switch back to using the pedometer for the rest of the workout.
If your phone is not counting steps while the screen is off, please read this post in our User Group for more information.
This could be related to how you hold your phone or your stride length. Take a short walk/run and manually count your paces, then check to make sure CardioTrainer approximately reflects this number. If not, change the position of your phone (put it in your pocket, hold it in your hand, strap it to your arm). Then, check to make sure your stride length is accurate. Stride length can be viewed and modified by selecting Settings > GPS / Pedometer Settings.
The stride length is the distance from one foot to another. There are many ways to calculate it, and we don't have official recommendations. However, there's some great dialogue in our user group. Search "stride length" and check out the suggestions. Google is also a great resource for finding how-to's.