Hardware Reference
In-Depth Information
To test the voltage:
1. Plug in all the peripherals you expect to use, and power on the Pi (and the pe-
ripherals).
2. Set your multimeter range to 20 V.
3. Touch the red lead of your multimeter to TP1 and the black lead to TP2 (as shown
in
Figure 1-15
).
Figure 1-15.
Testing the voltage
The Pi needs a good 5 V supply but has a tolerance of +/-0.25 V or so. That means
that, at a minimum, you should be seeing 4.75 V, preferably more like 4.8 V or more.
Below that, and either your peripherals will start acting up or the Pi might not even
boot at all. It might also reboot spontaneously.
You can also try unplugging various peripherals, using different monitors, removing
Ethernet, etc. Test again to see how the result changes.
It's Electric!
It's entirely possible that the Raspberry Pi is the first place you've gotten
this close to the electricity part of your electronics. If that's the case, it's
worth some light reading about how all this power stuff works. But at the
most basic level, you'll want to understand these three terms and the rela-
tionship among them:
