main.c

AT89S8252, AT89S53 SPI Program, This program shows how to configure and use the SPI in master mode

#include <AT898252.H>
#include <stdio.h>

/*-----------------------------------------------------------------------------
-----------------------------------------------------------------------------*/
#define AT250X0_WREN_OPCODE     (0x06)
#define AT250X0_WRDI_OPCODE     (0x04)
#define AT250X0_RDSR_OPCODE     (0x05)
#define AT250X0_WRSR_OPCODE     (0x01)
#define AT250X0_READ_OPCODE(a)  ((((a) & 0x0100) >> 0x05) | 0x03)
#define AT250X0_WRITE_OPCODE(a) ((((a) & 0x0100) >> 0x05) | 0x02)

#define AT250X0_ADDRESS_LSB(a)  ((a) & 0x00FF)

#define AT250X0_CS	P1_0

#define AT250X0_STAT_BUSY	0x01
#define AT250X0_STAT_WREN	0x02

/*-----------------------------------------------------------------------------
-----------------------------------------------------------------------------*/
unsigned char read_status (void)
{
unsigned char stat;

AT250X0_CS = 0;

SPDR = AT250X0_RDSR_OPCODE;
while ((SPSR & 0x80) == 0);

SPDR = 0xFF;
while ((SPSR & 0x80) == 0);
stat = SPDR;

AT250X0_CS = 1;

return (stat);
}

/*-----------------------------------------------------------------------------
-----------------------------------------------------------------------------*/
void write_enable (
  unsigned char flag)
{
AT250X0_CS = 0;

SPDR = (flag == 0) ? AT250X0_WRDI_OPCODE : AT250X0_WREN_OPCODE;
while ((SPSR & 0x80) == 0);

AT250X0_CS = 1;
}

/*-----------------------------------------------------------------------------
-----------------------------------------------------------------------------*/
void read_at250x0 (
  unsigned address,
  unsigned char *buf,
  unsigned length)
{
AT250X0_CS = 0;

SPDR = AT250X0_READ_OPCODE(address);
while ((SPSR & 0x80) == 0);

SPDR = AT250X0_ADDRESS_LSB(address);
while ((SPSR & 0x80) == 0);

while (length--)
  {
  SPDR = 0xFF;
  while ((SPSR & 0x80) == 0);
  *buf++ = SPDR;
  }

AT250X0_CS = 1;
}

/*-----------------------------------------------------------------------------
-----------------------------------------------------------------------------*/
void write_at250x0 (
  unsigned address,
  unsigned char *buf,
  unsigned length)
{
write_enable (1);

for (; length--; address++)
  {
  while (read_status () & AT250X0_STAT_BUSY);

  AT250X0_CS = 0;

  SPDR = AT250X0_WRITE_OPCODE(address);
  while ((SPSR & 0x80) == 0);

  SPDR = AT250X0_ADDRESS_LSB(address);
  while ((SPSR & 0x80) == 0);

  SPDR = *buf++;
  while ((SPSR & 0x80) == 0);

  AT250X0_CS = 1;
  }

write_enable (0);
}

/*-----------------------------------------------------------------------------
-----------------------------------------------------------------------------*/
void main (void)
{
unsigned i;
static unsigned char xdata buffer [20];

/*-----------------------------------------------
Initialize the serial port.
-----------------------------------------------*/
SCON  = 0x50;
TMOD |= 0x20;
TH1   = 221;
TR1   = 1;
TI    = 1;

/*-----------------------------------------------
-----------------------------------------------*/
SPCR = 0x53;   /* 01010011 */

/*-----------------------------------------------
-----------------------------------------------*/
while (1)
  {
  write_at250x0 (0, "This is a test", 15);
  read_at250x0 (0, buffer, sizeof(buffer));

  for (i = 0; i < sizeof(buffer); i++)
    printf ("Buffer[%u]=%2.2X\n", (unsigned) i, (unsigned) buffer[i]);
  }

/*-----------------------------------------------
-----------------------------------------------*/
}