ATmega8A Atmel Corporation, ATmega8A Datasheet - Page 160

• Manufacturer Part Number: ATmega8A
• Manufacturer: Atmel Corporation

Specifications of ATmega8A

• Flash (kbytes): 8 Kbytes
• Pin Count: 32
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 12
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 23
• Ext Interrupts: 2
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• 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): 1
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Pwm Channels: 3
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

19.10.5
8159D–AVR–02/11
UBRRL and UBRRH – USART Baud Rate Registers
• Bit 2:1 – UCSZ1:0: Character Size
The UCSZ1:0 bits combined with the UCSZ2 bit in UCSRB sets the number of data bits (Char-
acter Size) in a frame the Receiver and Transmitter use.
Table 19-7.
• Bit 0 – UCPOL: Clock Polarity
This bit is used for Synchronous mode only. Write this bit to zero when Asynchronous mode is
used. The UCPOL bit sets the relationship between data output change and data input sample,
and the synchronous clock (XCK).
Table 19-8.
The UBRRH Register shares the same I/O location as the UCSRC Register. See the
UBRRH/UCSRC Registers” on page 154
• Bit 15 – URSEL: Register Select
This bit selects between accessing the UBRRH or the UCSRC Register. It is read as zero when
reading UBRRH. The URSEL must be zero when writing the UBRRH.
• Bit 14:12 – Reserved Bits
These bits are reserved for future use. For compatibility with future devices, these bit must be
written to zero when UBRRH is written.
Bit
Read/Write
Initial Value
UCPOL
0
1
UCSZ2
0
0
0
0
1
1
1
1
Transmitted Data Changed (Output of TxD
Pin)
Rising XCK Edge
Falling XCK Edge
URSEL
UCSZ Bits Settings
UCPOL Bit Settings
R/W
R/W
15
7
0
0
R/W
14
R
–
6
0
0
UCSZ1
0
0
1
1
0
0
1
1
R/W
13
R
–
5
0
0
section which describes how to access this register.
R/W
12
R
–
4
0
0
UBRR[7:0]
UCSZ0
0
1
0
1
0
1
0
1
R/W
R/W
11
3
0
0
Received Data Sampled (Input on RxD
Pin)
Falling XCK Edge
Rising XCK Edge
R/W
R/W
Character Size
5-bit
6-bit
7-bit
8-bit
Reserved
Reserved
Reserved
9-bit
10
2
0
0
UBRR[11:8]
R/W
R/W
9
1
0
0
ATmega8A
R/W
R/W
8
0
0
0
“Accessing
UBRRH
UBRRL
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