The Serial Port is Dead! Long Live the Serial Port!
followed. Violating the
rules can result in your
PC assuming a USB bus
power fault and the PC
will then shut down (no
warning, just a black
screen and bye-bye to all
your unsaved work — this
is not an official fact, but
a personal observation).
Save your work frequently
when playing with these
devices and be prepared
to reboot your system.
The USB peripheral tells the USB host how
much power it needs in 100 mA units up to
500 mA. It cannot use more than 100 mA while
starting up before making a request for more
power. And the USB host can deny the
peripheral’s request for more power. Also, if the
USB host tells the peripheral to go into suspend
mode, it must not use more than 500 μA. This
can get complex. For instance, a device off a
USB bus-powered hub cannot use more than
100 mA, but you can have hubs with external
power that can supply the full 500 mA. For this
article, we will assume that the device is
powered either directly from a PC or from an externally
powered hub so that we can use up to 500 mA.
The BBUSB can be powered directly from the USB
bus or it can be powered from an external power source.
Figure 3 shows three ways to wire the BBUSB. First, you
can use the five volts from the USB bus; second, you can
use the BBUSB to convert the bus power to 3. 3 volts to
power other circuits on the breadboard; and third, you
can use external power between 3. 3 and five volts.
FIGURE 3. Power wiring.
FIGURE 4. Loop
Click the “Install from a list or specific location
(advanced)” radio button, then “Next>.”
• The Wizard will then ask “Please choose your search
and installation options.” Click the “Search for the best
drive in these locations” radio button, then click the check
box for “Include this location in the search.”
Using the BBUSB on a Breadboard
Before plugging the BBUSB into the USB port, you will
need to download the CDM 2.00.00 (or the most recent
version) drivers from ftdichip.com/Drivers/VCP.htm.
• Click on the browse button to locate the directory
containing FTDI’s CDM 2.00.00
(or the most
FIGURE 6. Port settings.
• Wire the BBUSB as in Figure 4.
• Plug a USB cable into your PC and the BBUSB.
• In the final
click “Finish.” You
will see a “Found
• Windows will display a Found
New Hardware Wizard, which
will ask you “Can Windows
connect to Windows Update to
search for software?” Click the
“No, not this time” radio button,
• The Wizard will then ask “What
do you want the wizard to do?”
FIGURE 5. Simple terminal.
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