Datasheet

page 34
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. For example if microcontroller has 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 3.22mV.
mikromedia
™
workStation v7 board provides an interface in form of two potentiometers for simulating analog input
voltages that can be routed to any of the 7 supported analog input pins of mikromedia
™
board.
ADC inputs
P1
10K
R1
220
VCC-3.3V
J2
P2
10K
R8
220
VCC-3.3V
J7
C4
100nF
C1
100nF
G0.0
G0.1
G0.2
G0.3
G0.4
A0
A1
DATA BUS
Enabling ADC inputs
In order to connect the output of the
potentiometer P1 to G0.0, G0.1, G0.2,
G0.3 or G0.4 analog mikromedia
™
inputs,
you have to place the jumper J2 in the
desired position. If you want to connect
potentiometer P2 to A0 or A1 analog
mikromedia
™
inputs, place jumper J7
in the desired position. By moving the
potentiometer knob, you can create
voltages in range from GND to VCC.
Figure 14-1: use J2 and J7 jumpers
to connect analog input lines with
potentiometers P1 and P2
Figure 14-2: Schematic of ADC input
other modules