ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 157

• Manufacturer Part Number: ATMEGA325-16AJ
• Description: 8-bit Microcontroller with In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

2570A–AVR–09/04
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 parame-
ters, disable 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 )
{
}
void USART_Init( unsigned int ubrr)
{
}
; Set baud rate
out
out
; Enable receiver and transmitter
ldi
out
; Set frame format: 8data, 2stop bit
ldi
out
ret
...
USART_Init(MYUBRR)
...
/* Set baud rate */
UBRRH = (unsigned char)(ubrr>>8);
UBRRL = (unsigned char)ubrr;
/* Enable receiver and transmitter */
UCSR0B = (1<<RXEN0)|(1<<TXEN0);
/* Set frame format: 8data, 2stop bit */
UCSR0C = (1<<USBS0)|(3<<UCSZ0);
1. The example code assumes that the part specific header file is included.
For I/O Registers located in extended I/O map, “IN”, “OUT”, “SBIS”, “SBIC”, “CBI”,
and “SBI” instructions must be replaced with instructions that allow access to
extended I/O. Typically “LDS” and “STS” combined with “SBRS”, “SBRC”, “SBR”, and
“CBR”.
UBRRH, r17
UBRRL, r16
r16, (1<<RXEN0)|(1<<TXEN0)
UCSR0B,r16
r16, (1<<USBS0)|(3<<UCSZ0)
UCSR0C,r16
(1)
(1)
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