M I K R O E L E K T R O N I K A S O F T W A R E A N D H A R D W A R E S O L U T I O N S F O R T H E E M B E D D E D W O R L D
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EasyAVR
USB
4
EasyAVR4 User
’
s Manual
MikroElektronika
Development
tools
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4.096V VOLTAGE REFERENCE
Figure 35.
4.096V voltage reference
Some of the Atmel’s microcontrollers have integrated A/D Converter (Analog-to-Digital
Converter). In order for A/D Converter to work, voltage reference must be used. It repre-
sents a maximum value that can be measured by microcontroller. EasyAVR4 uses 4.096V
voltage reference because number 4096 is a power of 2 which makes it easy to represent val-
ues as binary numbers in microcontroller. In case of the 10-bit A/D Converter the resolution
will be 4mV per bit. In case of the 12-bit A/D Converter the resolution will be 1mV per bit.
Analog input pins are placed on PORTA of microcontroller. In order to measure analog sig-
nal without interference, turn the coresponding switch on SW1 to OFF position. This will
disable connection of the used PORTA pin to the pull-up/down resistors.
Applications of A/D Conversion are various. Microcontroller takes analog signal from its
input pin and translates it into a digital value. Basically, you can measure any analog signal
that fits in range acceptable by MCU. With 4.096V voltage reference used (jumper J9 in
lower position) this range is 0V-4.096V. If you place jumper J9 in upper position 5V will be
used as voltage reference and therefor measure range will be 0V-5V.
VREF
4.096V
ON-BOARD
VREF
4.096V
ON-BOARD
