ATMEGA325-16AJ ATMEL [ATMEL Corporation], ATMEGA325-16AJ Datasheet - Page 145

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

2570A–AVR–09/04
Note:
The following code examples show how to initialize the SPI as a Master and how to per-
form a simple transmission. DDR_SPI in the examples must be replaced by the actual
Data Direction Register controlling the SPI pins. DD_MOSI, DD_MISO and DD_SCK
must be replaced by the actual data direction bits for these pins. E.g. if MOSI is placed
on pin PB5, replace DD_MOSI with DDB5 and DDR_SPI with DDRB.
Note:
Assembly Code Example
C Code Example
SPI_MasterInit:
SPI_MasterTransmit:
Wait_Transmit:
void SPI_MasterInit(void)
{
}
void SPI_MasterTransmit(char cData)
{
}
; Set MOSI and SCK output, all others input
ldi
out
; Enable SPI, Master, set clock rate fck/16
ldi
out
ret
; Start transmission of data (r16)
out
; Wait for transmission complete
sbis SPSR,SPIF
rjmp Wait_Transmit
ret
/* Set MOSI and SCK output, all others input */
DDR_SPI = (1<<DD_MOSI)|(1<<DD_SCK);
/* Enable SPI, Master, set clock rate fck/16 */
SPCR = (1<<SPE)|(1<<MSTR)|(1<<SPR0);
/* Start transmission */
SPDR = cData;
/* Wait for transmission complete */
while(!(SPSR & (1<<SPIF)))
1. See “Alternate Functions of Port B” on page 59 for a detailed description of how to
1. The example code assumes that the part specific header file is included.
;
define the direction of the user defined SPI pins.
r17,(1<<DD_MOSI)|(1<<DD_SCK)
DDR_SPI,r17
r17,(1<<SPE)|(1<<MSTR)|(1<<SPR0)
SPCR,r17
SPDR,r16
(1)
(1)
ATmega325/3250/645/6450
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