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| #include <p18f4550.h> //head file.
#include <spi.h>
#define cs LATCbits.LATC6 //define sd pin.
#define SSPIF PIR1bits.SSPIF
unsigned char r1=0;
void delay_100ms(void);
void spi_init(void); //spi init
void spi_low(void); //produce low band func(sd card init use.)
void spi_high(void); //produce high band func(sd card init use.)
unsigned char sd_reset(void); //sd card init func
unsigned char SD_SendCommand(char CMD,char ARG1,char ARG2,char ARG3,char ARG4,char CRC); //write sd card command func
unsigned char SPI_WriteByte(unsigned char val); //write one byte func.
void delay(void); //delay func.
/////////////////////////////////////////////////
//main
void main()
{
unsigned char loop,res;
//On désactive l'acquisition analogique
ADCON0=0x0f;
ADCON1=0x0f;
OpenSPI(SPI_FOSC_64, MODE_11, SMPEND);
while(1)
{
res= sd_reset(); //sd card init.
if(res) break; //if init is abnormal,exit and don't perform the next func.
printlcd('3');
}
}
////////////////////////////////////////////////
//spi init
void spi_init()
{
//TRISCbits.TRISC7=0; // SDO declarer en sortie
//TRISBbits.TRISB1=0; //SCK est declarer en sortie sur le maitre
//TRISBbits.TRISB0=1; //SCK est declarer en sortie sur le maitre
//TRISC=0xd0; //set SDI as input£¬other port c are output.
//TRISD=0X00; //set port d as output.
//TRISA=0X00; //set port a as output.
//ADCON1=0X07; //set port a as ordinary i/o.
SSPCON1=0x32; //high when idle.fosc/64
SSPSTAT=0x80; // rising edge,send data.
cs=1;
//SSPSTAT = SSPSTAT & 0b00111111; // registre port spi mode 11 osc/64
//SSPCON1 = 0b00110010; //clock middle
//LATCbits.LATC0=0;
//LATCbits.LATC1=0;
//PORTA=0XFF;
}
unsigned char SD_SendCommand(char CMD,char ARG1,char ARG2,char ARG3,char ARG4,char CRC)
{
unsigned char r1;
unsigned char retry1=0; //repeat count.
cs=0; //enable cs signal.
SPI_WriteByte(CMD); //write command.
SPI_WriteByte(ARG1);
SPI_WriteByte(ARG2);
SPI_WriteByte(ARG3);
SPI_WriteByte(ARG4);
SPI_WriteByte(CRC); //CRC check sum.
while((r1 = SPI_WriteByte(0xff)) == 0xff)//wait ack.
if(retry1++ > 100) break; //overtime exit.
cs=1; //clear cs.
return r1; //return the status value.
}
////////////////////////////////////////////////
//set low band.
void spi_low()
{
SSPCON1=0x32; //SPI clk use the system clk--fosc/64 0x32
}
////////////////////////////////////////////////
//set high band.
void spi_high()
{
SSPCON1=0x31; //SPI clk use the system clk--fosc/64 0x31
}
///////////////////////////////////////////////
//write one byte.
unsigned char SPI_WriteByte(unsigned char val)
{
SSPBUF = val; //load to send buffer
while(!SSPIF); //wait to finish sending.
SSPIF=0; //clear send finish flag.
return SSPBUF; //read the receive buffer(even the data is unvalid,it is still need cleared.)
}
////////////////////////////////////////////////
//SD reset.
unsigned char sd_reset()
{
unsigned char i,tmp;
unsigned char retry; //repeat times.
retry=0;
spi_low(); //use low band.
do
{
cs=1;
for(i=0;i<10;i++) SPI_WriteByte(0xff);
delay_100ms();
cs=0;
delay_100ms();
r1=SD_SendCommand(0x40,0,0,0,0,0x95);
retry++;
//if(retry>10) return 1; //overtime exit.
} while(r1 != 0x01); //wait IDLE command return.
retry = 0;
do
{
for(i=0;i<100;i++) SPI_WriteByte(0xff);
//r1 = SD_SendCommand(1, 0); //send Active command.
r1 = SD_SendCommand(0x41,0,0,0,0,0xff);
retry++;
if(retry>100) return 1; //overtime exit.
} while(r1); //wait Active command exit.
spi_high(); //use high band.
return 0; //return normal.
}
///////////////////////////////////////////////
//
void delay() //
{
int i; //
for(i=0x100;i--;); //
}
void delay_100ms()
{
int i;
for(i=0;i<=9;i++)
{
Delay10TCYx( 5);;
}
} |
