Page 167 - Making PIC Microcontroller Instruments and Controllers

tHE MOST BASTC OUESflON WE ilusl ANSWER 1S... l6i

Car odometer 0 to 999,000 miles 0.1 miles for short dislances

6-inch ruler 0 to 6 inches 1/32 inch at besl
Steel tape 0 to 96 inches 1/16 inch
M€chanical stop watch 0 to 30 minules 0.05 seconds

we will
Since we are interested in the use ofsensors that connect to microcontrollers,
restrict ouNelves to those sensors that provide an electrical signal or a signal that is easily
convefied into an electrical signal. Signals that dre easy to interface to a microcontrcller
are signals that have (changing) electrical properties like...

I Resistance
I Voltage
I Capacitance
I Reluctance
I Frequency

What competencies must be mastered in order to create miooconfoller-based instru
ments and controllers? Basically, you have a signal that must be transfomed into a read-
ing oi some sort in a one- or two-line display, or something similar What you must
master is the process between the two. Thus, the tasks involved break down tbis way:

l. Understanding the problem (this is much more important than it seems)
2. Capturing the signal
3, Filtering out the part you want
4. Conditioning the signal to make it acceptable to the PIC
jt
5, Converting to a digital format
6. Manipulating the digital data to create a readable value
7. Doing one or more of the following:
I Displaying the value on the LCD
I Transmitting the value to a computer for collection and storage
I Turning extemal device(s) on and off as necessary

Essentiaily, the chapten in this tutorial are devoted to these tasks.

The Most Basic
Question
I
We MustAnswers...

u hy \\ould T wanr ro build an in'rrumenl when
instruments to measue almost everything I am

interested in are already available off the shelfl