ATMEGA644A-PU Atmel, ATMEGA644A-PU Datasheet - Page 254

• Manufacturer Part Number: ATMEGA644A-PU
• Description: IC MCU AVR 64K FLASH 40PDIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644A-PU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 32
• Program Memory Size: 64KB (32K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 2K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 40-DIP (0.600", 15.24mm)
• Processor Series: ATmega
• Core: AVR
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: JTAG, TWI, SPI, USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• Minimum Operating Temperature: - 40 C
• Operating Temperature Range: - 40 C to + 85 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

22.8
8272A–AVR–01/10
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 22-3 on page 256
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 22-2 on page 255
(ADCn - ADCm) is selected with a gain of GAIN and a reference voltage of V
164A/164PA/324A/324PA/644A/644PA/1284/1284P
Figure 22-14 on page 255
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 22-4 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
⋅
1024
257). 0x000 represents analog ground, and
NEG
REF
⋅
the voltage on the negative input pin,
the selected voltage reference (see
REF
.
254