ATMEGA644PV ATMEL [ATMEL Corporation], ATMEGA644PV Datasheet - Page 251

• Manufacturer Part Number: ATMEGA644PV
• Description: 8-bit Microcontroller with 16/32/64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

21.8
8011D–AVR–02/07
ADC Conversion Result
After the conversion is complete (ADIF is high), the conversion result can be found in the ADC
Result Registers (ADCL, ADCH).
For single ended conversion, the result is
where V
Table 21-3 on page 253
0x3FF represents the selected reference voltage minus one LSB.
If differential channels are used, the result is
where V
GAIN the selected gain factor, and V
in two’s complement form, from 0x200 (-512d) through 0x1FF (+511d). Note that if the user
wants to perform a quick polarity check of the results, it is sufficient to read the MSB of the result
(ADC9 in ADCH). If this bit is one, the result is negative, and if this bit is zero, the result is posi-
tive.
Table 21-2 on page 252
(ADCn - ADCm) is selected with a gain of GAIN and a reference voltage of V
Figure 21-14 on page 252
IN
POS
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
and
shows the resulting output codes if the differential input channel pair
ADC
Table 21-4 on page
shows the decoding of the differential input range.
=
(
----------------------------------------------------------------------- -
V
ADC
POS
REF
the selected voltage reference. The result is presented
–
=
V
NEG
V
--------------------------
V
IN
REF
V
) GAIN 512
⋅
REF
ATmega164P/324P/644P
⋅
1024
254). 0x000 represents analog ground, and
NEG
REF
⋅
the voltage on the negative input pin,
the selected voltage reference (see
REF
.
251