Hardware Reference
In-Depth Information
From a quick glance at the datasheet, you can learn a considerable amount
about the microcontroller. You can ascertain that it has 32KB of programmable
flash memory, that it can be reprogrammed about 10,000 times, and that it can
operate from 1.8V to 5.5V (5V in the case of the Arduino). You can also learn
how many inputs/outputs (I/Os) it has, what special functions it has built in
(like hardware serial peripheral interface [SPI] and I
2
C interfaces), and what
resolution its analog-to-digital converter (ADC) is.
NOTE
Thisdatasheetisactuallyhundredsofpages,andtherecouldprobably
bean entire topic dedicated justtointerpretingit,soIwon'tgomuchfurtherhere.
However,throughouttheremainderofthisappendix,Idopointoutseveralmore
importanttopicstolookoutfor.
Datasheets as long as this one generally have PDF bookmarks built in that
make it easier to find what you're looking for. Of particular interest for your
Arduino adventures may be information about I/O ports, the timers, and the
various hardware serial interfaces. As one more example, consider Figure 13-1
from the datasheet's I/O section in the PDF, which is shown here as Figure A-2
for your convenience.
R
pu
Logic
See Figure
“General Digital I/O” for
Details
Pxn
C
pin
Figure A-2:
I/O pins diagram
Diagrams like this one can be found throughout the datasheet, and can give
you a deeper insight into how your Arduino is actually working. In this example,
you can see that the I/O pins all have protection diodes to protect them from
excessively high or negative voltages. It's also important to observe that there
is a known pin capacitance, which could have significant implications when
trying to determine the rise and fall times when switching the value of a pin.
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