ATMEGA128A-AU Atmel, ATMEGA128A-AU Datasheet - Page 193
![MCU 8BIT 128K ISP FLASH 64-TQFP](/photos/12/13/121332/313-64-tqfp_sml.jpg)
ATMEGA128A-AU
Manufacturer Part Number
ATMEGA128A-AU
Description
MCU 8BIT 128K ISP FLASH 64-TQFP
Manufacturer
Atmel
Series
AVR® ATmegar
Specifications of ATMEGA128A-AU
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)
2.7 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
JTAG
Maximum Clock Frequency
16 MHz
Number Of Programmable I/os
53
Number Of Timers
4
Operating Supply Voltage
2.7 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
On-chip Dac
10 bit, 8 Channel
Cpu Family
ATmega
Device Core
AVR
Device Core Size
8b
Frequency (max)
16MHz
Total Internal Ram Size
4KB
# I/os (max)
53
Number Of Timers - General Purpose
4
Operating Supply Voltage (typ)
3.3/5V
Operating Supply Voltage (max)
5.5V
Operating Supply Voltage (min)
2.7V
Instruction Set Architecture
RISC
Operating Temp Range
-40C to 85C
Operating Temperature Classification
Industrial
Mounting
Surface Mount
Pin Count
64
Package Type
TQFP
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
Q4784435
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
ATMEGA128A-AU
Manufacturer:
ATMEL
Quantity:
9 000
Company:
Part Number:
ATMEGA128A-AU
Manufacturer:
ATMEL
Quantity:
3 480
Part Number:
ATMEGA128A-AU
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
Company:
Part Number:
ATMEGA128A-AUR
Manufacturer:
ATMEL
Quantity:
3 000
Part Number:
ATMEGA128A-AUR
Manufacturer:
ATMEL/爱特梅尔
Quantity:
20 000
20.9.2
8151H–AVR–02/11
USART Control and Status Register A – UCSRnA
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-bit, 6-bit, 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 Transmit-
ter. 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 (that is, does not contain any unread data). If the receiver is disabled, 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 auto-
matically 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 Transmit Complete interrupt (see descrip-
tion 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 4 – FEn: Frame Error
This bit is set if the next character in the receive buffer had a Frame Error when received, that is,
when the first stop bit of the next character in the receive buffer is zero. This bit is valid until the
receive buffer (UDRn) is read. The FEn bit is zero when the stop bit of received data is one.
Always set this bit to zero when writing to UCSRnA.
Bit
Read/Write
Initial Value
RXCn
R
7
0
TXCn
R/W
6
0
UDREn
R
5
1
FEn
R
4
0
DORn
R
3
0
UPEn
R
2
0
U2Xn
ATmega128A
R/W
1
0
MPCMn
R/W
0
0
UCSRnA
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