ATmega32 Atmel Corporation, ATmega32 Datasheet - Page 160

• Manufacturer Part Number: ATmega32
• Manufacturer: Atmel Corporation

Specifications of ATmega32

• Flash (kbytes): 32 Kbytes
• Pin Count: 44
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 16
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 32
• Ext Interrupts: 3
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 1
• Uart: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: No
• Crypto Engine: No
• Sram (kbytes): 2
• Eeprom (bytes): 1024
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 2.7 to 5.5
• Operating Voltage (vcc): 2.7 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 3
• Output Compare Channels: 4
• Input Capture Channels: 1
• Pwm Channels: 4
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

USART Control and
Status Register A –
UCSRA
2503Q–AVR–02/11
data into the transmit Shift Register when the Shift Register is empty. Then the data will be seri-
ally transmitted on the TxD 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 – RXC: 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 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 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 auto-
matically 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 Transmit Complete interrupt (see descrip-
tion of the TXCIE bit).
• Bit 5 – UDRE: USART Data Register Empty
The UDRE Flag indicates if the transmit buffer (UDR) is ready to receive new data. If UDRE is
one, the buffer is empty, and therefore ready to be written. The UDRE Flag can generate a Data
Register empty Interrupt (see description of the UDRIE bit).
UDRE is set after a reset to indicate that the transmitter is ready.
• Bit 4 – FE: 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 (UDR) is read. The FE bit is zero when the stop bit of received data is one. Always
set this bit to zero when writing to UCSRA.
• Bit 3 – DOR: Data OverRun
This bit is set if a Data OverRun condition is detected. A Data OverRun occurs when the receive
buffer is full (two characters), it is a new character waiting in the receive Shift Register, and a
new start bit is detected. This bit is valid until the receive buffer (UDR) is read. Always set this bit
to zero when writing to UCSRA.
• Bit 2 – PE: Parity Error
This bit is set if the next character in the receive buffer had a Parity Error when received and the
parity checking was enabled at that point (UPM1 = 1). This bit is valid until the receive buffer
(UDR) is read. Always set this bit to zero when writing to UCSRA.
Bit
Read/Write
Initial Value
RXC
R
7
0
TXC
R/W
6
0
UDRE
R
5
1
FE
4
R
0
DOR
R
3
0
PE
R
2
0
U2X
R/W
1
0
ATmega32(L)
MPCM
R/W
0
0
UCSRA
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