A000048 Arduino, A000048 Datasheet - Page 180

ATMEGA328 MCU IC W/ Arduino UNO Bootloader

A000048

Manufacturer Part Number
A000048
Description
ATMEGA328 MCU IC W/ Arduino UNO Bootloader
Manufacturer
Arduino
Series
-r
Datasheets

Specifications of A000048

Accessory Type
Pre-Programed IC
Features
Powered Via USB Connection, AC-to-DC Adapter, Power Jack, ICSP Header
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
32KB (16K x 16)
Program Memory Type
FLASH
Eeprom Size
1K x 8
Ram Size
2K x 8
Voltage - Supply (vcc/vdd)
1.8 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
-
For Use With
ATmega328 Microcontrollers
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
19.3.2
8271C–AVR–08/10
Double Speed Operation (U2Xn)
Table 19-1
ing the UBRRn value for each mode of operation using an internally generated clock source.
Table 19-1.
Note:
Some examples of UBRRn values for some system clock frequencies are found in
page
The transfer rate can be doubled by setting the U2Xn bit in UCSRnA. Setting this bit only has
effect for the asynchronous operation. Set this bit to zero when using synchronous operation.
Setting this bit will reduce the divisor of the baud rate divider from 16 to 8, effectively doubling
the transfer rate for asynchronous communication. Note however that the Receiver will in this
case only use half the number of samples (reduced from 16 to 8) for data sampling and clock
recovery, and therefore a more accurate baud rate setting and system clock are required when
this mode is used. For the Transmitter, there are no downsides.
ATmega48A/48PA/88A/88PA/168A/168PA/328/328
Operating Mode
Asynchronous Normal mode
(U2Xn = 0)
Asynchronous Double Speed
mode (U2Xn = 1)
Synchronous Master mode
196).
BAUD
f
UBRRn
OSC
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 calculat-
Equations for Calculating Baud Rate Register Setting
Baud rate (in bits per second, bps)
System Oscillator clock frequency
Contents of the UBRRnH and UBRRnL Registers, (0-4095)
Equation for Calculating Baud
BAUD
BAUD
BAUD
=
=
=
Rate
----------------------------------------- -
16 UBRRn
-------------------------------------- -
8 UBRRn
-------------------------------------- -
2 UBRRn
(
(
(
(1)
f
f
f
OSC
OSC
OSC
+
+
+
1
1
1
)
)
)
UBRRn
Equation for Calculating
UBRRn
UBRRn
UBRRn Value
=
=
=
----------------------- - 1
16BAUD
------------------- - 1
8BAUD
------------------- - 1
2BAUD
f
f
f
OSC
OSC
OSC
Table
(see
180

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