Here is one fairly detailed tutorial. My worry is that there doesnt seem to be a delay in the write requests to ThingSpeak. You need to wait at least 15 s between requests to ThingSpeak for a free account. Hopefully you can make sure you add some delay. If you constantly bombard the ThingSpeak server, you might eventually be blocked.
In this tutorial, there is a delay of 2 seconds. If you have a paid license, that will work. If not, please increae the delay to 15 seconds at least.
