ATMEGA325P-20MU Atmel, ATMEGA325P-20MU Datasheet - Page 186

• Manufacturer Part Number: ATMEGA325P-20MU
• Description: IC MCU AVR 32K FLASH 64-QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA325P-20MU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K 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: 64-MLF®, 64-QFN
• Processor Series: ATMEGA32x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 2 KB
• Interface Type: SPI, UART, USI
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 54
• Number Of Timers: 3
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: EWAVR, EWAVR-BL
• Development Tools By Supplier: ATAVRDRAGON, ATSTK500, ATSTK600, ATAVRISP2, ATAVRONEKIT
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 10 bit, 8 Channel
• For Use With: ATSTK600-TQFP64 - STK600 SOCKET/ADAPTER 64-TQFP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAGATAVRISP2 - PROGRAMMER AVR IN SYSTEM
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: ATMEGA325P-16MU; ATMEGA325P-16MU

18.10.5
18.11 Examples of Baud Rate Setting
186
ATmega325P/3250P
UBRRnL and UBRRnH – USART Baud Rate Registers n
Figure 18-13. UCPOLn Bit Settings
• 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
R/W
15
R
–
7
0
0
R/W
14
Transmitted Data Changed (Output
of TxD Pin)
Rising XCK Edge
Falling XCK Edge
R
–
6
0
0
Error[%]
179). The error values are calculated using the following equation:
R/W
13
R
–
5
0
0
=
⎛
⎝
BaudRate
------------------------------------------------------- - 1
R/W
12
BaudRate
R
–
4
0
0
UBRRn[7:0]
Closest Match
R/W
R/W
11
3
0
0
–
⎞
⎠
R/W
R/W
10
2
0
0
•
UBRRn[11:8]
Received Data Sampled (Input
on RxD Pin)
Falling XCK Edge
Rising XCK Edge
100%
R/W
R/W
9
1
0
0
Table
R/W
R/W
”Asynchronous
8
0
0
0
18-3. UBRRn
8023F–AVR–07/09
UBRRnH
UBRRnL