ATMEGA649A-AU Atmel, ATMEGA649A-AU Datasheet - Page 179

IC MCU AVR 64K FLASH 64TQFP

ATMEGA649A-AU

Manufacturer Part Number
ATMEGA649A-AU
Description
IC MCU AVR 64K FLASH 64TQFP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheets

Specifications of ATMEGA649A-AU

Core Processor
AVR
Core Size
8-Bit
Speed
16MHz
Connectivity
SPI, UART/USART, USI
Peripherals
Brown-out Detect/Reset, LCD, POR, PWM, WDT
Number Of I /o
54
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
Processor Series
ATmega
Core
AVR
Data Bus Width
8 bit
Data Ram Size
4 KB
Interface Type
SPI, USART
Maximum Clock Frequency
16 MHz
Number Of Programmable I/os
54
Number Of Timers
3
Operating Supply Voltage
3.3 V
Maximum Operating Temperature
+ 85 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 40 C
Operating Temperature Range
- 40 C to + 85 C
Lead Free Status / RoHS Status
Lead free / RoHS Compliant

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
ATMEGA649A-AU
Manufacturer:
Atmel
Quantity:
10 000
Part Number:
ATMEGA649A-AUR
Manufacturer:
Atmel
Quantity:
10 000
19.3.1
8284A–AVR–10/10
Internal Clock Generation – The Baud Rate Generator
Figure 19-2. .Clock Generation Logic, Block Diagram
Signal description:
Internal clock generation is used for the asynchronous and the synchronous master modes of
operation. The description in this section refers to
The USART Baud Rate Register (UBRRn) and the down-counter connected to it function as a
programmable prescaler or baud rate generator. The down-counter, running at system clock
(f
the UBRRnL Register is written. A clock is generated each time the counter reaches zero. This
clock is the baud rate generator clock output (= f
baud rate generator clock output by 2, 8 or 16 depending on mode. The baud rate generator out-
put is used directly by the Receiver’s clock and data recovery units. However, the recovery units
use a state machine that uses 2, 8 or 16 states depending on mode set by the state of the
UMSELn, U2Xn and DDR_XCK bits.
Table 19-1 on page 180
for calculating the UBRRn value for each mode of operation using an internally generated clock
source.
osc
ATmega169A/169PA/329A/329PA/649A/649P/3290A/3290PA/6490A/6490P
), is loaded with the UBRRn value each time the counter has counted down to zero or when
txclk
rxclk
xcki
xcko
fosc
DDR_XCK
XCK
Pin
xcko
xcki
OSC
operation.
Transmitter clock (Internal Signal).
Receiver base clock (Internal Signal).
Input from XCK pin (internal Signal). Used for synchronous slave
Clock output to XCK pin (Internal Signal). Used for synchronous master
operation.
XTAL pin frequency (System Clock).
Down-Counter
Prescaling
contains equations for calculating the baud rate (in bits per second) and
Register
UBRR
Sync
UBRR+1
fosc
Detector
UCPOL
Edge
/2
Figure
osc
/(UBRRn+1)). The Transmitter divides the
/4
19-2.
/2
DDR_XCK
U2X
0
1
0
1
0
1
1
0
UMSEL
txclk
rxclk
179

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