Page 148 - Programming the Photon Getting Started With the Internet of Things

The relay shield uses a switch mode regulator that provides a constant 5 V to the
Particle and the relays. The regulator is rated at 1.2 A maximum output current, which is
sufficient to power the Photon and the four relays while still having power left over to

control other things that you connect to the Photon device. You can power the relay shield
using the DC socket or through a screw terminal with a voltage range between 7 and 20 V
DC.

Let’s take a look at some code that we can use to control a simple lightbulb. The relay

acts as our switch, which is normally open, and when pin D3 on the Photon is turned
HIGH, it activates the relay and switches on the light. The hardware for this experiment
can be seen in Table 7.2 and the layout diagram in Figure 7.4.

Description Appendix

Photon board M1

Relay shield M3

Power supply H7

Lightbulb H8

9-V battery H9

Equipment wire H10

Table 7.2 Components and Hardware

Figure 7.4 Photon relay layout diagram.