A couple of notes first:
- Please read this tutorial to the end, including the "tweaking" section. 99% of people having transfer problems simply didn't follow the advice in that chapter. Please do.
- If you have an HTC or LG phone running Lollipop (android 5) make sure that you get version 4.14 of the ANT+ radio service from google play, because earlier versions don't work on your device.
Step 0: check you Android device
If your device is in that list, you can skip Step 1, as you won't need the ANT+ USB dongle. In Step 2, you need only the Radio Service (don't install other stuff). In most cases, it will come preinstalled. However, you have to set the "force ant+ scan" option in my app.
If your device is not in that list, chances are it does not come with a big, size A usb port, so you might wonder how to plug in your ant+ dongle. The answer is quite simple: you need an OTG cable like this:

An OTG connector is usually cheap (a couple of euros / dollars) and it's generally speaking quite useful. For instance, you can use it to connect a keyboard to your android device.
Some tablets (some Samsung, some Asus, etc) do not have a micro-usb, and require a manufacturer-specific OTG adapter.
Step 1: check your ANT+ USB key
Step 2: install the ANT+ services
- The ANT Radio Service (which deals with ANT+ channels)
- The ANT USB Service (which deals with the USB key). This is not necessary if your device has an internal ANT+ chip.
Go ahead and do it!
Note that those apps require your Android device to be properly classified by Google Play as one with USB Host capabilities. Some devices, which are host-capable, are not properly classified in Google Play. In that case, unfortunately, the ANT+ services will result "incompatible" with your device and you won't be able to download them. As they're provided by Dynastream, there is little I can do about it - you'll have to find an alternative way to obtain and install the APK.
Step 3: check that everything works
If the dialog does not pop up, your USB key is not being recognized by the ANT+ Service. That's not part of Sportablet, so I can't really help you much on this side. Please check the Google Play page for the two ANT+ Service apps, as there are quite a few hints from users in the comments section. Sometimes, rebooting your tablet / phone with the ANT+ key connected is needed to make it work the first time (well, at least, that's what a few people told me - I never had to do it myself).
Now, if you want to double-check that it works, and you have a chest strap that you use with your Garmin, you can also download the free ANT+ Demo from Dynastream. It's a simple app that can connect with a chest strap or a scale and show you some values (it won't connect with your Garmin, just with the HR belt). If the ANT+ Demo works, everything has been set up properly. If you don't have a chest strap, just skip this step.
Step 4: configure your watch
Click Mode, then choose Settings > System > Data Transfer
Step 5: it's time to run the app!
UPDATE (July 2014). Due to a new version of the Dynastream Service, before you click get new please get into the options, scroll down to the ANT+ section, scroll down to the last entry (it should read "Force Claim Interface") and turn that ON. This is usually needed only if you use the ANT+ USB dongle, and not necessary if you have a built-in ANT+ chip in your phone.
NOTE: if you're using an Xperia or another device with internal ANT+ chip, remember to click options, and set "Force ANT+ scan" on. This will force the app to try using the internal chip.
device.Before you upload, it's advisable to turn off the gps in your Garmin. Now start the app, and click Get New (Sportablet) or Get Activities (Uploader). You may see that the app is trying to connect on different frequencies: that's ok as it's part of the ANT+ protocol. After a while, the app will ask you to accept pairing on your device:
After pairing, the app will try to download all your activities from the watch. If you have many, the transfer may fail, as ANT+ has very delicate timing and can easily go out of synch over long transfers. Still, downloaded activities are recovered (you can check that by clicking Done: downloaded activities will appear in the activity list). You can repeatedly download until you get them all.
NOTE: it is often necessary to set up a few options in the app, as well as to set up your tablet / phone properly. So, if the process fails or times out, please read the following section. It is *very* important that you turn off wifi / data / 3g / etc on your android device.
If you keep experiencing problems downloading, read on for a few tricks.
Tweaking : )
There are also a lot of settings under the ANT+ section of the app's Options.
- Make sure diagnostics is off.
- Lower the File Transfer Chunk. It's normally set to unlimited, as this is the setting that maximizes transfer speed. If you experience failures, move it down a notch to default; if it still fails, move it to small. It's relatively normal for some smartphones to require a small chunk.
- If it still fails, enable the "Delay Ack" option.
- If that is not enough, you can try to enable the power boost. In that case, make sure you don't have any other ANT+ equipment around, because increasing power will also increase the probability of interaction with distant devices.
If nothing works, get in touch. Enable logging, try an upload, stop it manually if needed, click the red "email log" button and maybe add a few lines to the email to explain what is going on on your side :-).