ATMEGA323-8AI Atmel, ATMEGA323-8AI Datasheet - Page 94
![IC AVR MCU 32K 8MHZ IND 44TQFP](/photos/6/70/67042/313-44-tqfp_sml.jpg)
ATMEGA323-8AI
Manufacturer Part Number
ATMEGA323-8AI
Description
IC AVR MCU 32K 8MHZ IND 44TQFP
Manufacturer
Atmel
Series
AVR® ATmegar
Datasheet
1.ATMEGA323L-4PC.pdf
(247 pages)
Specifications of ATMEGA323-8AI
Core Processor
AVR
Core Size
8-Bit
Speed
8MHz
Connectivity
I²C, SPI, UART/USART
Peripherals
Brown-out Detect/Reset, POR, PWM, WDT
Number Of I /o
32
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)
4.5 V ~ 5.5 V
Data Converters
A/D 8x10b
Oscillator Type
Internal
Operating Temperature
-40°C ~ 85°C
Package / Case
44-TQFP, 44-VQFP
Lead Free Status / RoHS Status
Contains lead / RoHS non-compliant
Other names
ATMEGA3238AI
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USART Register
Description
USART I/O Data Register –
UDR
USART Control and Status
Register A – UCSRA
94
ATmega323(L)
The USART Transmit Data Buffer Register and USART Receive Data Buffer Registers
share the same I/O address referred to as USART Data Register or UDR. The Transmit
Data Buffer Register (TXB) will be the destination for data written to the UDR Register
location. Reading the UDR Register location will return the contents of the Receive Data
Buffer Register (RXB).
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 UDRE Flag in the UCSRA Register is
set. Data written to UDR when the UDRE Flag is not set, will be ignored by the USART
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 TxD pin.
The Receive Buffer consists of a two level FIFO. The FIFO will change its state when-
ever 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 – RXC: USART Receive Complete
This flag bit is one when there are unread data in the receive buffer and zero 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 RXC bit will become zero.
The RXC Flag can be used to generate a Receive Complete interrupt (see description of
the RXCIE bit).
• Bit 6 – TXC: USART Transmit Complete
This flag bit is set one 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 (UDR). The
TXC 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 TXC Flag can generate a Trans-
mit Complete interrupt (see description of the TXCIE bit).
Bit
$0C ($2C) Read
$0C ($2C) Write
Read/Write
Initial Value
Bit
$0B ($2B)
Read/Write
Initial Value
RXC
R
7
0
R/W
7
0
TXC
R/W
6
0
R/W
6
0
UDRE
R
5
1
R/W
5
0
R/W
FE
R
4
0
4
0
RXB[7:0]
TXB[7:0]
R/W
DOR
3
0
R
3
0
R/W
2
0
PE
R
2
0
R/W
1
0
U2X
R/W
1
0
R/W
0
0
MPCM
R/W
1457G–AVR–09/03
0
0
UDR (Write)
UDR (Read)
UCSRA
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