Let's summarize what we did in this chapter. As usual, we connected a BLE module to our Arduino board so that it can receive commands via the Android phone. We also connected a simple relay module to the board, to control it via an Android application. Then we designed an application using the Android speech engine to control the relay depending on what the user says to the Android phone.

In the next chapter, we will use another feature of the Android phone to control Arduino projects: NFC. We will use NFC to control the state of a relay just by putting our phone in front of an Arduino NFC shield.