ATmega1281R231 Atmel Corporation, ATmega1281R231 Datasheet - Page 211

• Manufacturer Part Number: ATmega1281R231
• Manufacturer: Atmel Corporation

Specifications of ATmega1281R231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 16 MHz
• Max I/o Pins: 54
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 8
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 6
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

2549N–AVR–05/11
check that there are no unread data in the receive buffer. Note that the TXCn Flag must be
cleared before each transmission (before UDRn is written) if it is used for this purpose.
The following simple USART initialization code examples show one assembly and one C func-
tion that are equal in functionality. The examples assume asynchronous operation using polling
(no interrupts enabled) and a fixed frame format. The baud rate is given as a function parameter.
For the assembly code, the baud rate parameter is assumed to be stored in the r17:r16
Registers.
Note:
More advanced initialization routines can be made that include frame format as parameters, dis-
able interrupts and so on. However, many applications use a fixed setting of the baud and
control registers, and for these types of applications the initialization code can be placed directly
in the main routine, or be combined with initialization code for other I/O modules.
Assembly Code Example
C Code Example
USART_Init:
#define FOSC 1843200// Clock Speed
#define BAUD 9600
#define (MYUBRR FOSC/16/BAUD-1)
void main( void )
{...
USART_Init ( MYUBRR );
...} // main
void USART_Init( unsigned int ubrr){
/* Set baud rate */
UBRRH = (unsigned char)(ubrr>>8);
UBRRL = (unsigned char)ubrr;
/* Enable receiver and transmitter */
UCSRB = (1<<RXEN)|(1<<TXEN);
/* Set frame format: 8data, 2stop bit */
UCSRC = (1<<USBS)|(3<<UCSZ0);
} // USART_Init
; Set baud rate
sts
sts
ldi
sts
; Enable receiver and transmitter
ldi
sts UCSRnB,r16
; Set frame format: 8data, 1stop bit
ldi
sts
ret
1.
See “About Code Examples” on page 11.
UBRRnH, r17
UBRRnL, r16
r16, (1<<U2Xn)
UCRnA, r16
r16, (1<<RXENn)|(1<<TXENn)
r16, (2<<UMSELn)|(3<<UCSZn0)
UCSRnC,r16
(1)
(1)
ATmega640/1280/1281/2560/2561
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