ATMEGA644A-PU Atmel, ATMEGA644A-PU Datasheet - Page 196

• 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

Table 18-10. Examples of UBRRn Settings for Commonly Used Oscillator Frequencies (Continued)
1.
8272A–AVR–01/10
Baud
Rate
(bps)
2400
4800
9600
14.4k
19.2k
28.8k
38.4k
57.6k
76.8k
115.2k
230.4k
250k
0.5M
1M
Max.
(1)
UBRR = 0, Error = 0.0%
UBRR
95
47
23
15
11
7
5
3
2
1
0
0
–
–
230.4 kbps
f
U2Xn = 0
osc
= 3.6864 MHz
Error
-7.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
–
164A/164PA/324A/324PA/644A/644PA/1284/1284P
UBRR
191
95
47
31
23
15
11
7
5
3
1
1
0
–
460.8 kbps
U2Xn = 1
Error
-7.8%
-7.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
UBRR
103
51
25
16
12
8
6
3
2
1
0
–
–
0
f
U2Xn = 0
osc
250 kbps
= 4.0000 MHz
Error
-3.5%
-7.0%
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
8.5%
8.5%
0.0%
–
–
UBRR
207
103
51
34
25
16
12
8
6
3
1
1
0
–
U2Xn = 1
0.5 Mbps
Error
-0.8%
-3.5%
-7.0%
0.2%
0.2%
0.2%
0.2%
2.1%
0.2%
8.5%
8.5%
0.0%
0.0%
–
UBRR
191
95
47
31
23
15
11
7
5
3
1
1
0
–
460.8 kbps
f
U2Xn = 0
osc
= 7.3728 MHz
Error
-7.8%
-7.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
–
UBRR
191
383
95
63
47
31
23
15
11
7
3
3
1
0
921.6 kbps
U2Xn = 1
Error
-7.8%
-7.8%
-7.8%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
196