spi_at250x0.ini

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

/*-----------------------------------------------
Define the state and address for the AT250x0.
-----------------------------------------------*/
define char spi_at250x0_state
define int  spi_at250x0_address
define char spi_at250x0_status

/*-----------------------------------------------
MAP the memory area to use for the SPI RAM.
-----------------------------------------------*/
map X:0x700000,X:0x70FFFF READ WRITE

/*-----------------------------------------------
This function implements the state maching for
the AT250x0.

State       Transition
-------------------------------------------------
0: WREN  -> 0
0: WRDI  -> 0
0: RDSR  -> 0
0: Read  -> 1: Get Address LSB -> 2: Read Byte <-
0: Write -> 3: Get Address LSB -> 4: Write Byte -> 5 <-

1: Get Addr LSB -> 2
2: Read Byte(s) -> 2

3: Get Addr LSB -> 4
4: Write Byte   -> 5
-----------------------------------------------*/
func char spi_at250x0 (char st) {
unsigned char opcode;

printf ("AT250X0: STATE %u\n", (unsigned) st);

switch (st)
  {
  case 0:  /* Get OPCode */
    opcode = SPI_OUT & 0x0007;
    printf ("AT250X0: OPCODE %u\n", (unsigned) opcode);

    switch (opcode)
      {
      case 1: /* WRSR */
        return (0);

      case 2: /* Write */
        printf ("AT250X0: WRITE OPCODE Detected\n");
        spi_at250x0_address = (SPI_OUT & 0x08) << 5;
        return (3);

      case 3: /* Read */
        printf ("AT250X0: READ OPCODE Detected\n");
        spi_at250x0_address = (SPI_OUT & 0x08) << 5;
        return (1);

      case 4: /* WRDI */
        spi_at250x0_status &= ~0x02; /* Clear Write Enable Bit */
        return (0);

      case 5: /* RDSR */
        SPI_IN = spi_at250x0_status;
        return (5);

      case 6: /* WREN */
        spi_at250x0_status |= 0x02; /* Set Write Enable Bit */
        return (0);
      }
    return (0);

  case 1:  /* Get Address LSB for READ */
    spi_at250x0_address |= (SPI_OUT & 0xFF);
    printf ("AT250X0: Address %4.4X Detected\n", spi_at250x0_address);
    return (2);

  case 2:  /* Read */
    printf ("AT250X0: Read %2.2X from address %4.4X\n", 'A', spi_at250x0_address);
    SPI_IN = _rbyte(X:0x700000 + spi_at250x0_address);
    spi_at250x0_address = (spi_at250x0_address + 1) % 512;
    return (2);

  case 3:  /* Get Address LSB for WRITE */
    spi_at250x0_address |= (SPI_OUT & 0xFF);
    printf ("AT250X0: Address %4.4X Detected\n", spi_at250x0_address);
    return (4);

  case 4:  /* Write */
    if (spi_at250x0_status & 0x02)
      {
      printf ("AT250X0: Write %2.2X to address %4.4X\n", SPI_OUT, spi_at250x0_address);
      _wbyte(X:0x700000 + spi_at250x0_address, SPI_OUT);
      spi_at250x0_status |= 0x01;
      }
    return (5);

  case 5:  /* Instruction End */
    return (5);
  }

return (0);
}

/*-----------------------------------------------
This signal function watches the AT89S8252 SPI
port for writes.  If there is an SPI port output
and if P1.0 is LO (AT250X0 chip select) then
interpret the SPI output data and run the
state machine.
-----------------------------------------------*/
signal void spi_watcher (void) {

spi_at250x0_state = 0;

while (1) {
  wwatch (SPI_OUT);
  printf ("SPI_OUT Detected\n");

  if ((PORT1 & 0x01) == 0)
    {
    printf ("Calling AT250X0 Routines\n");
    spi_at250x0_state = spi_at250x0 (spi_at250x0_state);

    if (spi_at250x0_status & 0x01)
      swatch (0.000100);
      spi_at250x0_status &= ~0x01;
    }
  else
    {
    printf ("Resetting AT250X0 Routines\n");
    spi_at250x0_state = 0;
    }
  }
}

/*-----------------------------------------------
This signal monitors writes to Port 1.  If the
AT250X0 Chip Select is raised HI, reset the
AT250X0.
-----------------------------------------------*/
signal void port1_watcher (void) {

while (1) {
  wwatch (PORT1);
  if ((PORT1 & 0x01) == 1)
    {
    printf ("Resetting AT250X0 Routines\n");
    spi_at250x0_state = 0;
    }
  }
}

/*-----------------------------------------------
Enable the signal function for SPI writes.
Enable the signal function for PORT 1 writes.
-----------------------------------------------*/
spi_watcher ();
port1_watcher ();

/*-----------------------------------------------
-----------------------------------------------*/