ATMEGA644-20PU Atmel, ATMEGA644-20PU Datasheet - Page 247

• Manufacturer Part Number: ATMEGA644-20PU
• Description: IC AVR MCU FLASH 64K 40DIP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA644-20PU

• 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): 2.7 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: ATMEGA64x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: 2-Wire/SPI/USART
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 32
• Number Of Timers: 3
• Operating Supply Voltage: 2.7 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: Through Hole
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT, ATAVRRZ541, ATAVRRAVEN, ATAVRRZRAVEN, ATAVRRZUSBSTICK, ATAVRRZ201
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 8-ch x 10-bit
• Controller Family/series: AVR MEGA
• No. Of I/o's: 32
• Eeprom Memory Size: 2KB
• Ram Memory Size: 4KB
• Cpu Speed: 20MHz
• No. Of Timers: 3
• Rohs Compliant: Yes
• Package: 40PDIP
• Device Core: AVR
• Family Name: ATmega
• Maximum Speed: 20 MHz
• For Use With: ATSTK600-TQFP44 - STK600 SOCKET/ADAPTER 44-TQFPATSTK600-DIP40 - STK600 SOCKET/ADAPTER 40-PDIP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

2593N–AVR–07/10
Figure 21-14. Differential Measurement Range
Table 21-2.
Example:
V
V
V
...
V
V
V
...
V
V
V
ADCn
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADCm
ADMUX = 0xED (ADC3 - ADC2, 10x gain, 2.56V reference, left adjusted result)
Voltage on ADC3 is 300 mV, voltage on ADC2 is 500 mV.
ADCR = 512 × 10 × (300 - 500) / 2560 = -400 = 0x270
ADCL will thus read 0x00, and ADCH will read 0x9C. Writing zero to ADLAR right adjusts
the result: ADCL = 0x70, ADCH = 0x02.
+ 0.999 V
+ 0.998 V
+ 0.001 V
- 0.001 V
- 0.999 V
- V
- V
+ V
REF
REF
REF
/GAIN
/GAIN
/GAIN
Correlation between Input Voltage and Output Codes
REF
REF
REF
REF
REF
/GAIN
/GAIN
/GAIN
/GAIN
/GAIN
Read code
0x1FF
0x1FF
0x1FE
...
0x001
0x000
0x3FF
...
0x201
0x200
Output Code
0x3FF
0x1FF
0x000
0
0x200
Corresponding Decimal Value
511
511
510
...
1
0
-1
...
-511
-512
V
REF
/GAIN Differential Input
ATmega644
Voltage (Volts)
247