ATMEGA128-16AU Atmel, ATMEGA128-16AU Datasheet - Page 189

• Manufacturer Part Number: ATMEGA128-16AU
• Description: IC AVR MCU 128K 16MHZ 5V 64TQFP
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA128-16AU

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 16MHz
• Connectivity: EBI/EMI, I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 53
• Program Memory Size: 128KB (64K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 4K x 8
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• Processor Series: ATMEGA128x
• Core: AVR8
• Data Bus Width: 8 bit
• Data Ram Size: 4 KB
• Interface Type: 2-Wire, JTAG, SPI, USART
• Maximum Clock Frequency: 16 MHz
• Number Of Programmable I/os: 53
• Number Of Timers: 4
• Operating Supply Voltage: 4.5 V to 5.5 V
• 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
• Controller Family/series: AVR MEGA
• No. Of I/o's: 53
• Eeprom Memory Size: 4096Byte
• Ram Memory Size: 4KB
• Cpu Speed: 16MHz
• Rohs Compliant: Yes
• For Use With: ATSTK600-TQFP64 - STK600 SOCKET/ADAPTER 64-TQFP770-1007 - ISP 4PORT ATMEL AVR MCU SPI/JTAG770-1005 - ISP 4PORT FOR ATMEL AVR MCU JTAG770-1004 - ISP 4PORT FOR ATMEL AVR MCU SPIATAVRISP2 - PROGRAMMER AVR IN SYSTEMATJTAGICE2 - AVR ON-CHIP D-BUG SYSTEMATSTK501 - ADAPTER KIT FOR 64PIN AVR MCUATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

USART Register
Description
USARTn I/O Data Register –
UDRn
USART Control and Status
Register A – UCSRnA
2467M–AVR–11/04
The USARTn Transmit Data Buffer Register and USARTn Receive Data Buffer Regis-
ters share the same I/O address referred to as USARTn Data Register or UDRn. The
Transmit Data Buffer Register (TXBn) will be the destination for data written to the
UDRn Register location. Reading the UDRn Register location will return the contents of
the receive data buffer register (RXBn).
For 5-, 6-, or 7-bit characters the upper unused bits will be ignored by the Transmitter
and set to zero by the Receiver.
The transmit buffer can only be written when the UDREn flag in the UCSRAn Register is
set. Data written to UDRn when the UDREn flag is not set, will be ignored by the
USARTn Transmitter. When data is written to the transmit buffer, and the Transmitter is
enabled, the Transmitter will load the data into the Transmit Shift Register when the
Shift Register is empty. Then the data will be serially transmitted on the TxDn pin.
The receive buffer consists of a two level FIFO. The FIFO will change its state whenever
the receive buffer is accessed. Due to this behavior of the receive buffer, do not use
read modify write instructions (SBI and CBI) on this location. Be careful when using bit
test instructions (SBIC and SBIS), since these also will change the state of the FIFO.
• Bit 7 – RXCn: USART Receive Complete
This flag bit is set when there are unread data in the receive buffer and cleared when the
receive buffer is empty (i.e., does not contain any unread data). If the receiver is dis-
abled, the receive buffer will be flushed and consequently the RXCn bit will become
zero. The RXCn flag can be used to generate a Receive Complete interrupt (see
description of the RXCIEn bit).
• Bit 6 – TXCn: USART Transmit Complete
This flag bit is set when the entire frame in the Transmit Shift Register has been shifted
out and there are no new data currently present in the transmit buffer (UDRn). The
TXCn flag bit is automatically cleared when a transmit complete interrupt is executed, or
it can be cleared by writing a one to its bit location. The TXCn flag can generate a Trans-
mit Complete interrupt (see description of the TXCIEn bit).
• Bit 5 – UDREn: USART Data Register Empty
The UDREn flag indicates if the transmit buffer (UDRn) is ready to receive new data. If
UDREn is one, the buffer is empty, and therefore ready to be written. The UDREn flag
can generate a Data Register Empty interrupt (see description of the UDRIEn bit).
UDREn is set after a reset to indicate that the Transmitter is ready.
Bit
Read/Write
Initial Value
Bit
Read/Write
Initial Value
R/W
RXCn
7
0
R
7
0
R/W
6
0
TXCn
R/W
6
0
R/W
UDREn
5
0
R
5
1
R/W
4
0
FEn
RXBn[7:0]
TXBn[7:0]
R
4
0
R/W
DORn
3
0
3
R
0
R/W
UPEn
2
0
R
2
0
R/W
1
0
U2Xn
R/W
ATmega128
1
0
R/W
MPCMn
0
0
R/W
0
0
UDRn (Read)
UDRn (Write)
UCSRnA
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