ATMEGA162V-8AJ Atmel, ATMEGA162V-8AJ Datasheet - Page 169

• Manufacturer Part Number: ATMEGA162V-8AJ
• Description: IC MCU AVR 16K 5V 8MHZ 44-TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA162V-8AJ

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 8MHz
• Connectivity: EBI/EMI, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 35
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-TQFP, 44-VQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -

Internal Clock
Generation – The
Baud Rate Generator
2513K–AVR–07/09
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 (UBRR) and the down-counter connected to it function as a
programmable prescaler or baud rate generator. The down-counter, running at system clock
(fosc), is loaded with the UBRR value each time the counter has counted down to zero or when
the UBRRL Register is written. A clock is generated each time the counter reaches zero. This
clock is the baud rate generator clock output (= fosc/(UBRR+1)). The Transmitter divides the
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
UMSEL, U2X and DDR_XCK bits.
Table 70
the UBRR value for each mode of operation using an internally generated clock source.
Table 70. Equations for Calculating Baud Rate Register Setting
Note:
Some examples of UBRR values for some system clock frequencies are found in
page
Operating Mode
Asynchronous Normal Mode
(U2X = 0)
Asynchronous Double Speed
Mode (U2X = 1)
Synchronous Master Mode
txclk
rxclk
xcki
xcko
fosc
BAUD Baud rate (in bits per second, bps)
f
UBRR Contents of the UBRRH and UBRRL Registers, (0 - 4095)
OSC
191).
1. The baud rate is defined to be the transfer rate in bit per second (bps).
contains equations for calculating the baud rate (in bits per second) and for calculating
Transmitter clock. (Internal Signal)
Receiver base clock. (Internal Signal)
Input from XCK pin (internal Signal). Used for synchronous slave operation.
Clock output to XCK pin (Internal Signal). Used for synchronous master
operation.
XTAL pin frequency (System Clock).
System Oscillator clock frequency
BAUD
BAUD
BAUD
Equation for Calculating
Baud Rate
=
=
=
-------------------------------------- -
16 UBRR
---------------------------------- -
8 UBRR
---------------------------------- -
2 UBRR
(
(
(
f
f
f
OSC
OSC
OSC
(1)
Figure
+
+
+
1
1
1
)
)
)
76.
Equation for Calculating
UBRR
UBRR
UBRR
UBRR Value
ATmega162/V
=
=
=
----------------------- - 1
16BAUD
------------------- - 1
8BAUD
------------------- - 1
2BAUD
f
f
f
OSC
OSC
OSC
–
–
–
Table 78
(see
169