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 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. EasyMx PRO
™
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.
other modules
page 38
ADC inputs
DATA BUS
P1
10K
R56
220
VCC-3.3V
J9
M2X5
PE4
PE5
PE6
PE7
PD7
Enabling ADC inputs
In order to connect the output of the
potentiometer P1 to PE7, PE6, PE5, PE4
or PD7 analog microcontroller inputs, you
have to place the jumper J9 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
EasyMx PRO
v7