Hardware Reference
In-Depth Information
Given the price of the hardware I am sure we can all make do and work with what we have.
Pi In, Pi Out
Let's start off with the most common ports on the Pi. Figure
1-1
is a reference image of a Raspberry Pi.
Figure 1-1.
Raspberry Pi Model B
Let's look at the Pi from the top side, starting off with the USB port and moving clockwise around the board since
I am sure all of you know what a USB port looks like by now.
USB Port
The USB functions are provided by the SMSC LAN9512 on both the Model A and Model B. The LAN9512 is an
interesting package and a very good way to save PCB space; I can see why the foundation has selected this chip. The
USB ports on the Pi are USB 2.0 and provide everything you normally would need from a USB port with one small
drawback. The maximum recommended current draw is 100 milliampere or mA for short, compared to the possible
500 mA of a normal USB port in device-negotiated mode. So if you need to draw more than 100 mA you should look at
a powered USB hub or power the device externally. Devices like a USB flash drive should be fine; a 2.5-inch external
self-powered hard drive will not be fine on the other hand. So give some thought to what you're going to plug into
your Pi's USB ports.
While it's unlikely you will damage the Pi your device may not work or it may act very oddly. There is another
potential issue with the USB ports and also the LAN port. Why the LAN port, you ask?
