ATMEGA128-16AU SL383 Atmel, ATMEGA128-16AU SL383 Datasheet - Page 241

• Manufacturer Part Number: ATMEGA128-16AU SL383
• Manufacturer: Atmel

ADC Conversion
Result
2467S–AVR–07/09
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 97 on page 242
sents 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 96
selected with a gain of GAIN and a reference voltage of V
Figure 119. Differential Measurement Range
Figure 119
- V
REF
IN
POS
/GAIN
shows the resulting output codes if the differential input channel pair (ADCn - ADCm) is
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
shows the decoding of the differential input range.
and
ADC
Table 98 on page
=
Output Code
(
----------------------------------------------------------------------- -
0x3FF
V
ADC
REF
POS
0x1FF
0x000
the selected voltage reference. The result is presented
–
0
=
V
0x200
NEG
V
--------------------------
243). 0x000 represents ground, and 0x3FF repre-
V
IN
REF
V
) GAIN 512
⋅
REF
⋅
1024
NEG
REF
⋅
REF
the voltage on the negative input pin,
the selected voltage reference (see
.
V
REF
ATmega128
/GAIN Differential Input
Voltage (Volts)
241