ATTINY2313A-MUR Atmel, ATTINY2313A-MUR Datasheet - Page 129

• Manufacturer Part Number: ATTINY2313A-MUR
• Description: MCU AVR 2K FLASH 20MHZ 20QFN
• Manufacturer: Atmel
• Series: AVR® ATtinyr

Specifications of ATTINY2313A-MUR

• 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: 18
• Program Memory Size: 2KB (1K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 128 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 1.8 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Data Converters: -

14.7
14.7.1
14.7.2
8246A–AVR–11/09
Data Reception – The USART Receiver
Receiving Frames with 5 to 8 Data Bits
Receiving Frames with 9 Data Bits
The USART Receiver is enabled by writing the Receive Enable (RXEN) bit in the UCSRB Regis-
ter to one. When the Receiver is enabled, the normal pin operation of the RxD pin is overridden
by the USART and given the function as the Receiver’s serial input. The baud rate, mode of
operation and frame format must be set up once before any serial reception can be done. If syn-
chronous operation is used, the clock on the XCK pin will be used as transfer clock.
The Receiver starts data reception when it detects a valid start bit. Each bit that follows the start
bit will be sampled at the baud rate or XCK clock, and shifted into the Receive Shift Register until
the first stop bit of a frame is received. A second stop bit will be ignored by the Receiver. When
the first stop bit is received, i.e., a complete serial frame is present in the Receive Shift Register,
the contents of the Shift Register will be moved into the receive buffer. The receive buffer can
then be read by reading the UDR I/O location.
The following code example shows a simple USART receive function based on polling of the
Receive Complete (RXC) flag. When using frames with less than eight bits the most significant
bits of the data read from the UDR will be masked to zero. The USART has to be initialized
before the function can be used.
Note:
The function simply waits for data to be present in the receive buffer by checking the RXC flag,
before reading the buffer and returning the value.
If 9-bit characters are used (UCSZ=7) the ninth bit must be read from the RXB8 bit in UCSRB
before reading the low bits from the UDR. This rule applies to the FE, DOR and UPE Status
Flags as well. Read status from UCSRA, then data from UDR. Reading the UDR I/O location will
Assembly Code Example
C Code Example
USART_Receive:
unsigned char USART_Receive( void )
{
}
; Wait for data to be received
sbis UCSRA, RXC
rjmp USART_Receive
; Get and return received data from buffer
in
ret
/* Wait for data to be received */
while ( !(UCSRA & (1<<RXC)) )
/* Get and return received data from buffer */
return UDR;
1. See “Code Examples” on page 6.
r16, UDR
;
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