Datasheet

page 38
v7
Digital signals have two discrete states, which are decoded as
high and low, and interpreted as logic 1 and logic 0. Analog
signals, on the other hand, are continuous, and can have
any value within dened range. A/D converters are
specialized circuits which can convert analog signals
(voltages) into a digital representation, usually in
form of an integer number. The value of this
number is linearly dependent on the input
voltage value. Most microcontrollers
nowadays internally have A/D
converters connected to one or
more input pins. Some of the
most important parameters of
A/D converters are conversion
time and resolution. Conversion
time determines how fast can an
analog voltage be represented in form of
a digital number. This is an important parameter
if you need fast data acquisition. The other parameter
is resolution. Resolution represents the number of discrete
steps that supported voltage range can be divided into. It determines
the sensitivity of the A/D converter. Resolution is represented in maximum number of bits that resulting number occupies. Most
microcontrollers have 10-bit resolution, meaning that maximum value of conversion can be represented with 10 bits, which converted to
integer is 2
10
=1024. This means that supported voltage range, for example from 0-3.3V, can be divided into 1024 discrete steps of about 3.222mV.
EasyPIC Fusion
™
v7 provides an interface in form of potentiometer for simulating analog input voltages that can be routed to any of the 5 supported
analog input pins.
P1
10K
R42
220
VCC-3.3V
J8
C28
100nF
RB9
RB0
RB8
RB1
RB4
E18
10uF
DATA BUS
Enabling ADC inputs
In order to connect the output of the
potentiometer P1 to RB0, RB1, RB4, RB8
or RB9 analog microcontroller inputs, you
have to place the jumper J8 in the desired
position. By moving the potentiometer
knob, you can create voltages in range
from GND to VCC.
Figure 24-1:
Schematic of ADC
input
ADC inputs
other modules