ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 288

• Manufacturer Part Number: ATmega1281R231
• Manufacturer: Atmel Corporation

Specifications of ATmega1281R231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 16 MHz
• Max I/o Pins: 54
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 6
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

26.7
2549N–AVR–05/11
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 26-3 on page 289
0x3FF represents the selected reference voltage minus one LSB.
If differential channels are used, the result is
where V
and V
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.
ing of the differential input range.
Table 26-2 on page 289
(ADCn - ADCm) is selected with a gain of GAIN and a reference voltage of V
Figure 26-15. Differential Measurement Range
REF
IN
POS
the selected voltage reference. The result is presented in two’s complement form, from
is the voltage on the selected input pin and V
is the voltage on the positive input pin, V
- V
REF
and
shows the resulting output codes if the differential input channel pair
Table 26-4 on page
ATmega640/1280/1281/2560/2561
ADC
Output Code
0x3FF
ADC
0x1FF
0x000
0x200
=
(
---------------------------------------------------- -
0
=
V
POS
V
--------------------------
IN
V
–
⋅
REF
V
V
1024
290). 0x000 represents analog ground, and
REF
NEG
NEG
REF
) 512
⋅
the voltage on the negative input pin,
the selected voltage reference (see
Figure 26-15
V
REF
Differential Input
Voltage (Volts)
REF
shows the decod-
.
288