ATMEGA645V-8AU Atmel, ATMEGA645V-8AU Datasheet - Page 161
ATMEGA645V-8AU
Manufacturer Part Number
ATMEGA645V-8AU
Description
IC AVR MCU FLASH 64K 64TQFP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheet
1.ATMEGA325-16MU.pdf
(362 pages)
Specifications of ATMEGA645V-8AU
Core Processor
AVR
Core Size
8-Bit
Speed
8MHz
Connectivity
SPI, UART/USART, USI
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
53
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
64-TQFP, 64-VQFP
Processor Series
ATMEGA64x
Core
AVR8
Data Bus Width
8 bit
Data Ram Size
4 KB
Interface Type
SPI, UART, USI
Maximum Clock Frequency
8 MHz
Number Of Programmable I/os
54
Number Of Timers
3
Operating Supply Voltage
1.8 V to 5.5 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
On-chip Adc
10 bit, 8 Channel
Controller Family/series
AVR MEGA
No. Of I/o's
54
Eeprom Memory Size
2KB
Ram Memory Size
4KB
Cpu Speed
8MHz
No. Of Timers
3
Rohs Compliant
Yes
Data Rom Size
2 KB
Height
1 mm
Length
14 mm
Supply Voltage (max)
5.5 V
Supply Voltage (min)
2.7 V
Width
14 mm
For Use With
ATSTK600-TQFP64 - STK600 SOCKET/ADAPTER 64-TQFP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAG770-1005 - ISP 4PORT FOR ATMEL AVR MCU JTAG770-1004 - ISP 4PORT FOR ATMEL AVR MCU SPIATAVRISP2 - PROGRAMMER AVR IN SYSTEM
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Available stocks
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Manufacturer
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Price
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19.3.2
19.3.3
19.3.4
2570M–AVR–04/11
Double Speed Operation (U2Xn)
External Clock
Synchronous Clock Operation
Table 19-1.
Note:
Some examples of UBRR values for some system clock frequencies are found in
(see
The transfer rate can be doubled by setting the U2Xn bit in UCSRnA. Setting this bit only has
effect for the asynchronous operation. Set this bit to zero when using synchronous operation.
Setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling
the transfer rate for asynchronous communication. Note however that the Receiver will in this
case only use half the number of samples (reduced from 16 to 8) for data sampling and clock
recovery, and therefore a more accurate baud rate setting and system clock are required when
this mode is used. For the Transmitter, there are no downsides.
External clocking is used by the synchronous slave modes of operation. The description in this
section refers to
External clock input from the XCK pin is sampled by a synchronization register to minimize the
chance of meta-stability. The output from the synchronization register must then pass through
an edge detector before it can be used by the Transmitter and Receiver. This process intro-
duces a two CPU clock period delay and therefore the maximum external XCK clock frequency
is limited by the following equation:
Note that f
add some margin to avoid possible loss of data due to frequency variations.
When synchronous mode is used (UMSELn = 1), the XCK pin will be used as either clock input
(Slave) or clock output (Master). The dependency between the clock edges and data sampling
Operating Mode
Asynchronous Normal
mode (U2Xn = 0)
Asynchronous Double
Speed mode
(U2Xn = 1)
Synchronous Master
mode
page
BAUD
f
UBRR
OSC
1. The baud rate is defined to be the transfer rate in bit per second (bps)
osc
176).
depends on the stability of the system clock source. It is therefore recommended to
Equations for Calculating Baud Rate Register Setting
Figure 19-2
Baud rate (in bits per second, bps)
System Oscillator clock frequency
Contents of the UBRRH and UBRRL Registers, (0-4095)
BAUD
BAUD
BAUD
Equation for Calculating
for details.
Baud Rate
=
=
=
-------------------------------------- -
16 UBRR
---------------------------------- -
8 UBRR
---------------------------------- -
2 UBRR
(
(
(
f
f
f
f
XCK
OSC
OSC
OSC
(1)
ATmega325/3250/645/6450
<
+
+
+
f
---------- -
1
1
OSC
1
4
)
)
)
Equation for Calculating
UBRR
UBRR
UBRR
UBRR Value
=
=
=
----------------------- - 1
16BAUD
------------------- - 1
8BAUD
------------------- - 1
2BAUD
f
f
f
OSC
OSC
OSC
–
–
–
Table 19-4
161
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