ATMEGA88P-20MUR Atmel, ATMEGA88P-20MUR Datasheet - Page 197

• Manufacturer Part Number: ATMEGA88P-20MUR
• Description: MCU AVR 8KB FLASH 20MHZ 32QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA88P-20MUR

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 23
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 512 x 8
• Ram Size: 1K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

19.10.5
19.11 Examples of Baud Rate Setting
8025L–AVR–7/10
UBRRnL and UBRRnH – USART Baud Rate Registers
Table 19-8.
• Bit 15:12 – Reserved Bits
These bits are reserved for future use. For compatibility with future devices, these bit must be
written to zero when UBRRnH is written.
• Bit 11:0 – UBRR11:0: USART Baud Rate Register
This is a 12-bit register which contains the USART baud rate. The UBRRnH contains the four
most significant bits, and the UBRRnL contains the eight least significant bits of the USART
baud rate. Ongoing transmissions by the Transmitter and Receiver will be corrupted if the baud
rate is changed. Writing UBRRnL will trigger an immediate update of the baud rate prescaler.
For standard crystal and resonator frequencies, the most commonly used baud rates for asyn-
chronous operation can be generated by using the UBRRn settings in
values which yield an actual baud rate differing less than 0.5% from the target baud rate, are
bold in the table. Higher error ratings are acceptable, but the Receiver will have less noise resis-
tance when the error ratings are high, especially for large serial frames (see
Operational Range” on page
Bit
Read/Write
Initial Value
UCPOLn
0
1
UCPOLn Bit Settings
Transmitted Data Changed (Output of
TxDn Pin)
Rising XCKn Edge
Falling XCKn Edge
R/W
15
R
–
7
0
0
R/W
14
R
–
6
0
0
Error[%]
190). The error values are calculated using the following equation:
R/W
13
R
–
5
0
0
=
⎛
⎝
BaudRate
------------------------------------------------- - 1
R/W
BaudRate
12
R
–
4
0
0
UBRRn[7:0]
Closest Match
R/W
R/W
11
3
0
0
ATmega48P/88P/168P
Received Data Sampled (Input on RxDn
Pin)
Falling XCKn Edge
Rising XCKn Edge
–
⎞
⎠
•
R/W
R/W
10
2
0
0
UBRRn[11:8]
100%
R/W
R/W
9
1
0
0
Table
R/W
R/W
”Asynchronous
8
0
0
0
19-9. UBRRn
UBRRnH
UBRRnL
197