ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 292

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

ADC Conversion Result
292
ATmega640/1280/1281/2560/2561
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
ence (see Table 128 on page 294 and Table 129 on page 295). 0x000 represents
analog ground, and 0x3FF represents the selected reference voltage minus one LSB.
If differential channels are used, the result is
where V
input pin, and V
plement form, from 0x200 (-512d) through 0x1FF (+511d). Note that if the user wants to
perform a quick polarity check of the result, it is sufficient to read the MSB of the result
(ADC9 in ADCH). If the bit is one, the result is negative, and if this bit is zero, the result
is positive. Figure 127 shows the decoding of the differential input range.
Table 127 shows the resulting output codes if the differential input channel pair (ADCn -
ADCm) is selected with a gain of GAIN and a reference voltage of V
Figure 127. Differential Measurement Range
- V
REF
IN
POS
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
REF
the selected voltage reference. The result is presented in two’s com-
ADC
Output Code
0x3FF
ADC
0x1FF
0x000
0x200
=
0
(
---------------------------------------------------- -
=
V
POS
V
--------------------------
IN
V
–
⋅
REF
V
V
1024
REF
NEG
) 512
⋅
NEG
REF
the voltage on the negative
the selected voltage refer-
V
REF
REF
.
Differential Input
Voltage (Volts)
2549K–AVR–01/07