MEGA128CAN Datasheet, PDF (165/413 Pages) ATMEL Corporation – Microcontroller WITH 128K BYTES OF ISP FLASH AND CAN CONTROLLER

4250E–CAN–12/04
AT90CAN128
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 con-
trolling 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 PB2, replace DD_MOSI
with DDB2 and DDR_SPI with DDRB.
Assembly Code Example⁽¹⁾
SPI_MasterInit:
; Set MOSI and SCK output, all others input
ldi r17,(1<<DD_MOSI)|(1<<DD_SCK)
out DDR_SPI,r17
; Enable SPI, Master, set clock rate fck/16
ldi r17,(1<<SPE)|(1<<MSTR)|(1<<SPR0)
out SPCR,r17
ret
SPI_MasterTransmit:
; Start transmission of data (r16)
out SPDR,r16
Wait_Transmit:
; Wait for transmission complete
in r17,SPSR
sbrs r17,SPIF
rjmp Wait_Transmit
ret
C Code Example⁽¹⁾
void SPI_MasterInit(void)
{
/* 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);
}
void SPI_MasterTransmit(char cData)
{
/* Start transmission */
SPDR = cData;
/* Wait for transmission complete */
while(!(SPSR & (1<<SPIF)))
;
}
Note: 1. The example code assumes that the part specific header file is included.
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