ATmega6450 Atmel Corporation, ATmega6450 Datasheet - Page 160
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ATmega6450
Manufacturer Part Number
ATmega6450
Description
Manufacturer
Atmel Corporation
Specifications of ATmega6450
Flash (kbytes)
64 Kbytes
Pin Count
100
Max. Operating Frequency
16 MHz
Cpu
8-bit AVR
Hardware Qtouch Acquisition
No
Max I/o Pins
69
Ext Interrupts
25
Usb Speed
No
Usb Interface
No
Spi
2
Twi (i2c)
1
Uart
1
Graphic Lcd
No
Video Decoder
No
Camera Interface
No
Adc Channels
8
Adc Resolution (bits)
10
Adc Speed (ksps)
15
Analog Comparators
1
Resistive Touch Screen
No
Temp. Sensor
No
Crypto Engine
No
Sram (kbytes)
4
Eeprom (bytes)
2048
Self Program Memory
YES
Dram Memory
No
Nand Interface
No
Picopower
No
Temp. Range (deg C)
-40 to 85
I/o Supply Class
1.8 to 5.5
Operating Voltage (vcc)
1.8 to 5.5
Fpu
No
Mpu / Mmu
no / no
Timers
3
Output Compare Channels
4
Input Capture Channels
1
Pwm Channels
4
32khz Rtc
Yes
Calibrated Rc Oscillator
Yes
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20.3.1
2570N–AVR–05/11
Internal Clock Generation – The Baud Rate Generator
Figure 20-2. Clock Generation Logic, Block Diagram
Signal description:
operation.
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
(f
the UBRRL 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 20-1
ing the UBRR value for each mode of operation using an internally generated clock source.
osc
), is loaded with the UBRR value each time the counter has counted down to zero or when
txclk
rxclk
xcki
xcko
fosc
DDR_XCK
XCK
Pin
contains equations for calculating the baud rate (in bits per second) and for calculat-
xcko
xcki
OSC
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
Register
UBRR
Sync
UBRR+1
fosc
Detector
UCPOL
Edge
/2
ATmega325/3250/645/6450
Figure
osc
/(UBRR+1)). The Transmitter divides the
/4
20-2.
/2
DDR_XCK
U2X
0
1
0
1
0
1
1
0
UMSEL
txclk
rxclk
160