I am designing a microphone with a two way communication using Tread and Zigbee protocol. I am looking at the eval boards offered by NXP. So, NXP offers 2 boards 1. Tower and 2. Freedom. Which one the two do you recommend me to start working with? I have not worked with either thread/zigbee protocol before. So with the help of the eval board I could work on it and understand it better.