Making Android Accessories with IOIO

Chapter 2. Intruder Alarm

In this chapter we’ll develop a motion sensor intruder alarm with a difference: it sends you a text message when it detects movement. The project has very few components apart from the IOIO. It uses just a PIR movement detector and a resistor.

Figure 2-1 shows the interface to the IOIO Alarm. There are two fields, one for the phone number to send the text to and one for the message to be sent when movement is detected.

Figure 2-1. IOIO intruder alarm

Under those fields appear two toggle buttons. The first toggles test mode on and off. When in test mode, no actual text messages are sent. A message appears on the screen momentarily instead. The second toggle button is labeled RUN; pressing this will start the monitoring after a period of 10 seconds, which gives you enough time to leave the room.

Warning

This project sends SMS text messages, which may cost you money. So do not get carried away when you are testing it.

Hardware

In addition to your IOIO, which you should have kitted out with sockets and a power lead, you will need to buy the items in Table 2-1.

Table 2-1. Parts bin

Quantity	Description	SparkFun SKU	Farnell code	Newark code
1	PIR Module	SEN-08630
1	10 kΩ 0.5W metal film resistor	9339787	38K5141

The schematic diagram for the project is shown in Figure 2-2.

Figure 2-2. The ...