Hardware Reference
In-Depth Information
Summary
In this chapter you got to use the I2C bus, one of the many buses on the Raspberry Pi. I started off with the simple
character LCD that you used throughout the chapter: the cheap and plentiful HD44780 or one of its many clones.
I would expect you could find or scavenge one of these LCDs from anywhere; they turn up in a lot more places than
you would think.
Up next was the I2C bus; this older bus is still widely used in today's technology. It's not the fastest bus in the
world but you don't really need a PCI bus to drive a character LCD. You also found out that you can chain more than
one device off the I2C bus, making it an even better value for the Raspberry Pi.
After that it was time to bust out the breadboard and dig into some chips. In this chapter you used the
PCF8574AN shift register as the workhorse for converting the serial signal on the I2C bus to a parallel signal. Shift
registers are pretty cool when you think about them. After this chapter you could in theory use most parallel devices
on your Raspberry Pi, without the need to have a parallel port or to use up valuable GPIO pins.
Of course, what good is all this hardware if you don't have any software to use on it? In the last part of this chapter
I showed you how to set up
lcdproc
and how to make use of the generic
lcdproc
client. Then I showed you how easy
it can be to write your own
lcdproc
client by using a simple Ruby script. You can now use your LCD for anything you
may think of. Or you may want to use it in Chapter 7 when you set up XBMC on your Raspberry Pi.
