Datasheet

133
8006H–AVR–10/09
ATtiny24/44/84
Figure 16-1. Analog to Digital Converter Block Schematic
16.3 Operation
The ADC converts an analog input voltage to a 10-bit digital value through successive approxi-
mation. The minimum value represents GND and the maximum value represents the reference
voltage.The voltage reference for the ADC may be selected by writing to the REFS1..0 bits in
ADMUX. The VCC supply, the AREF pin or an internal 1.1V voltage reference may be selected
as the ADC voltage reference.
The analog input channel and differential gain are selected by writing to the MUX5..0 bits in
ADMUX. Any of the eight ADC input pins ADC7..0 can be selected as single ended inputs to the
ADC. For differential measurements all analog inputs next to each other can be selected as a
input pair. Every input is also possible to measure with ADC3. These pairs of differential inputs
are measured by ADC trough the differential gain amplifier.
ADC CONVERSION
COMPLETE IRQ
8-BIT DATA BUS
15 0
ADC MULTIPLEXER
SELECT (ADMUX)
ADC CTRL. & STATUS A
REGISTER (ADCSRA)
ADC DATA REGISTER
(ADCH/ADCL)
ADIE
ADATE
ADSC
ADEN
ADIF
ADIF
MUX4...MUX0
ADPS0
ADPS1
ADPS2
CONVERSION LOGIC
10-BIT DAC
+
-
SAMPLE & HOLD
COMPARATOR
INTERNAL
REFERENCE
1.1V
MUX DECODER
V
CC
ADC7
ADC6
ADC5
ADC4
REFS1..REFS0
ADLAR
CHANNEL SELECTION
ADC[9:0]
ADC MULTIPLEXER
OUTPUT
PRESCALER
TRIGGER
SELECT
ADTS2...ADTS0
INTERRUPT
FLAGS
START
+
-
GAIN SELECTION
GAIN
AMPLIFIER
NEG.
INPUT
MUX
SINGLE ENDED / DIFFERENTIAL SELECTION
TEMPERATURE
SENSOR
ADC8
BIN
ADC3
ADC2
ADC1
ADC0
POS.
INPUT
MUX
AGND
ADC CTRL. & STATUS B
REGISTER (ADCSRB)
AREF