Hardware Reference
In-Depth Information
In addition to providing the usual access to the Pi's GPIO pins, the Gertboard also
provides these features:
•
Twelve
buffered
I/O pins
•
Three push buttons
•
Six open collector drivers (up to 50 V, 500 mA)
•
A motor controller (18 V, 2 A)
•
A two-channel 8/10/12 bit digital-to-analog converter
•
A two-channel 10-bit analog-to-digital converter
•
A 28-pin DIP ATmega microcontroller
This provides a ready-made learning environment for the student, who is anxious
to wire up something and just “make it work.” Many of the 3-volt logic and buffering
concerns are eliminated, allowing the student to focus on projects.
Bare Metal
Despite the availability of nice adapters like the Gertboard, the focus of this text is on
interfacing directly to the Pi's 3 V GPIO pins. Here are some of the reasons:
•
No specific adapter has to be purchased for the projects in this topic.
•
Any specified adapter can go out of production.
•
You'll not likely use an expensive adapter on each
deployed
Pi.
•
Bare metal interfacing will exercise your design skills.
If we were to do projects with only wiring involved, there wouldn't be much learning
involved. Facing the design issues that arise from working with weak 3 V GPIOs driving
the outside world will be much more educational.
The third bullet speaks to finished projects. If you're building a robot, for example,
you're not going to buy Gertboards everywhere you need to control a motor or read
sensor data. You're going to want to economize and build that yourself. This topic is
designed to help you
face
those kinds of challenges.
