Hardware Reference
In-Depth Information
Building the Circuit
So what you need to do as the inal step is construct this circuit. I much prefer making cir-
cuits on strip board and not solderless breadboard. he problem with breadboard is that it
can make poor or intermittent contact which means that you could appear to have wired it
up correctly but it is not. herefore you can waste a lot of time just jiggling the components
around hoping this will make it work. A small piece of veroboard or prototyping strip board
is all you need. You can also use sockets for the integrated circuits, which means you can
reuse them or replace them if they are damaged. he physical layout of the circuit is shown in
Figure 11-8.
Figure 11-8:
he physical
layout of the
beat driver
circuit.
his shows the view of the board looking from the top or component side. he dotted lines
indicate the copper strips on the underside of the board.
Running the Circuit
After you have built the circuit you need to attach it to your audio input and wire the output,
5V and ground into the PiFace board. Adjust the threshold knob until it is at the mid-point,
and boot up your Raspberry Pi. hen run the sequence program and switch to the external
step. Start of the music and adjust the volume until you start to see the sequence advance.
If it won't turn up far enough, you might have to increase the value of R2; try changing it to
470K. hen adjust the threshold until you see the sequence pick up the beat of the music.
You might have to go back and adjust the volume. It works better on some types of music
than others.
