Page 348 - ARM Based Microcontroller Projects Using MBED

334 14. ADVANCED PROJECTS

board. The relays are controlled (turned ON or OFF) from an Android mobile phone (or any
other device with network access, e.g., PC or tablet) by sending TCP-based commands to
the Wi-Fi expansion board through a Wi-Fi link established using a network router.

14.3.2 Aim

The aim of this project is to show how a number of relays connected to the Nucleo-F411RE
development board can be controlled wirelessly through a Wi-Fi link using the Nucleo Wi-Fi
expansion board. Additionally, the project shows how a TCP-based program can be devel-
oped on the Nucleo development board in order to communicate with a TCP application
running on an Android mobile phone.

14.3.3 Block Diagram
There are many different Nucleo expansion boards that can be used to simplify the design
of projects using the Nucleo development boards. Some expansion boards include sensors
such as accelerometer, temperature and humidity sensor, magnetometer, NFC card reader,
etc., some include indicators such as LEDs, some include actuators such as DC motor drivers
or stepper motor drivers, and some others include Wi-Fi or Bluetooth communication mod-
ules. The expansion boards plug on top of the Nucleo development boards through the
Arduino connectors.
The block diagram of the project is shown in Fig. 14.1. Here, a Wi-Fi router provides
the wireless connection between the mobile phone and the Wi-Fi expansion board.
A 4-channel relay board is connected to the Nucleo-F411RE development board. Various
indicators or actuators can be connected to these relays.

14.3.4 TCP and UDP Communications

When devices are connected to each other wirelessly through a Wi-Fi router, communication
between these devices can be established using either the TCP or the UDP protocols.

FIG. 14.1 Block diagram of the project.