User`s guide

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
PIC® 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 0-5V, can be divided into 1024 discrete steps of about 4.88mV.
EasyPIC
™
v7 provides an interface in form of two potentiometers for simulating analog input voltages that can be routed to
any of the 10 supported analog input pins.
ADC inputs
P2
10K
R64
220
P1
10K
R63
220
J15
J16
VCC-MCU
VCC-MCU
RA2
RA1
RA0
RA3
RA5
RB2
RB1
RB0
RB3
RB4
DATA BUS
Enabling ADC inputs
In order to connect the output of the
potentiometer P1 to RA0, RA1, RA2,
RA3 or RA5 analog microcontroller inputs,
you have to place the jumper J15 in the
desired position. If you want to connect
potentiometer P2 to any of the RB0 – RB4
analog microcontroller inputs, place jumper
J16 in the desired position. By moving
the potentiometer knob, you can create
voltages in range from GND to VCC.
Figure 17-1: use J15 and J16 jumpers
to connect analog input lines with
potentiometers P1 and P2
page 30
Figure 17-2:
Schematic of ADC
input
modules