f33x_spi0_eeprom_polled_mode.c

芯科原厂所有c8051fxx程序的例子。

// P1.6  -  Unassigned,  Open-Drain, Digital
// P1.7  -  Unassigned,  Open-Drain, Digital
//
//-----------------------------------------------------------------------------
void PORT_Init (void)
{
   P0MDOUT  = 0x1D;
   P1MDOUT  = 0x08;
   P0SKIP   = 0x80;
   P1SKIP   = 0x08;
   XBR0     = 0x03;
   XBR1     = 0x40;
}

//-----------------------------------------------------------------------------
// TIMER2_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Initializes Timer2 to be clocked by SYSCLK for use as a delay timer.
//
//-----------------------------------------------------------------------------
void TIMER2_Init (void)
{
   CKCON    |= 0x10;
}

//-----------------------------------------------------------------------------
// UART0_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Configures the UART0 using Timer1, for <BAUDRATE> and 8-N-1. Once this is
// set up, the standard printf function can be used to output data.
//
//-----------------------------------------------------------------------------
void UART0_Init (void)
{
   SCON0 = 0x10;                       // SCON0: 8-bit variable bit rate
                                       //        level of STOP bit is ignored
                                       //        RX enabled
                                       //        ninth bits are zeros
                                       //        clear RI0 and TI0 bits
   if (SYSCLK/BAUDRATE/2/256 < 1)
   {
      TH1 = -(SYSCLK/BAUDRATE/2);
      CKCON &= ~0x0B;                  // T1M = 1; SCA1:0 = xx
      CKCON |=  0x08;
   } 
   else if (SYSCLK/BAUDRATE/2/256 < 4)
   {
      TH1 = -(SYSCLK/BAUDRATE/2/4);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 01
      CKCON |=  0x09;
   }
   else if (SYSCLK/BAUDRATE/2/256 < 12)
   {
      TH1 = -(SYSCLK/BAUDRATE/2/12);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 00
   } else
   {
      TH1 = -(SYSCLK/BAUDRATE/2/48);
      CKCON &= ~0x0B;                  // T1M = 0; SCA1:0 = 10
      CKCON |=  0x02;
   }

   TL1 = TH1;                          // init Timer1
   TMOD &= ~0xf0;                      // TMOD: timer 1 in 8-bit autoreload
   TMOD |=  0x20;
   TR1 = 1;                            // START Timer1
   TI0 = 1;                            // Indicate TX0 ready
}

//-----------------------------------------------------------------------------
// SPI0_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Configures SPI0 to use 4-wire Single-Master mode. The SPI timing is 
// configured for Mode 0,0 (data centered on first edge of clock phase and 
// SCK line low in idle state). The SPI clock is set to 1.75 MHz. The NSS pin 
// is set to 1.
//
//-----------------------------------------------------------------------------
void SPI0_Init()
{
   SPI0CFG   = 0x40;
   SPI0CN    = 0x0D;
   
   // The equation for SPI0CKR is (SYSCLK/(2*F_SCK_MAX))-1, but this yields
   // a SPI frequency that is slightly more than 2 MHz. But, 2 MHz is the max 
   // frequency spec of the EEPROM used here. So, the "-1" term is omitted 
   // in the following usage:
   SPI0CKR   = (SYSCLK/(2*F_SCK_MAX));
}

//-----------------------------------------------------------------------------
// Init_Device
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// Calls all device initialization functions.
//
//-----------------------------------------------------------------------------
void Init_Device (void)
{
   PCA0_Init ();
   OSCILLATOR_Init ();
   PORT_Init ();
   TIMER2_Init ();
   UART0_Init ();
   SPI0_Init ();
}

//-----------------------------------------------------------------------------
// Support Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// Delay_us
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : 1. time_us - time delay in microseconds
//                   range: 1 to 255
//
// Creates a delay for the specified time (in microseconds) using TIMER2. The 
// time tolerance is approximately +/-50 ns (1/SYSCLK + function call time).
//
//-----------------------------------------------------------------------------
void Delay_us (BYTE time_us)
{
   TR2   = 0;                          // Stop timer
   TF2H  = 0;                          // Clear timer overflow flag
   TMR2  = -( (UINT)(SYSCLK/1000000) * (UINT)(time_us) );
   TR2   = 1;                          // Start timer
   while (!TF2H);                      // Wait till timer overflow occurs
   TR2   = 0;                          // Stop timer
}

//-----------------------------------------------------------------------------
// Delay_ms
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : 1. time_ms - time delay in milliseconds
//                   range: 1 to 255
//
// Creates a delay for the specified time (in milliseconds) using TIMER2. The 
// time tolerance is approximately +/-50 ns (1/SYSCLK + function call time).
//
//-----------------------------------------------------------------------------
void Delay_ms (BYTE time_ms)
{
   BYTE i;

   while(time_ms--)
      for(i = 0; i< 10; i++)           // 10 * 100 microsecond delay
         Delay_us (100);
}

//-----------------------------------------------------------------------------
// EEPROM_Write
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : 1. address - the destination EEPROM address.
//                   range: 0 to EEPROM_CAPACITY
//                2. value - the value to write.
//                   range: 0x00 to 0xFF
//
// Writes one byte to the specified address in the EEPROM. This function polls
// the EEPROM status register after the write operation, and returns only after
// the status register indicates that the write cycle is complete. This is to
// prevent from having to check the status register before a read operation.
//
//-----------------------------------------------------------------------------
void EEPROM_Write (UINT address, BYTE value)
{
   // Writing a byte to the EEPROM is a five-step operation.
   
   // Step1: Set the Write Enable Latch to 1
   NSSMD0   = 0;                       // Step1.1: Activate Slave Select
   SPI0DAT  = EEPROM_CMD_WREN;         // Step1.2: Send the WREN command
   while (!SPIF);                      // Step1.3: Wait for end of transfer
   SPIF     = 0;                       // Step1.4: Clear the SPI intr. flag
   NSSMD0   = 1;                       // Step1.5: Deactivate Slave Select
   Delay_us (1);                       // Step1.6: Wait for at least 
                                       //          T_NSS_DISABLE_MIN
   // Step2: Send the WRITE command
   NSSMD0   = 0;
   SPI0DAT  = EEPROM_CMD_WRITE;
   while (!SPIF);
   SPIF     = 0;
   
   // Step3: Send the EEPROM destination address (MSB first)
   SPI0DAT  = (BYTE)((address >> 8) & 0x00FF);
   while (!SPIF);
   SPIF     = 0;
   SPI0DAT  = (BYTE)(address & 0x00FF);
   while (!SPIF);
   SPIF     = 0;
   
   // Step4: Send the value to write
   SPI0DAT  = value;
   while (!SPIF);
   SPIF     = 0;
   NSSMD0   = 1;
   Delay_us (1);
   
   // Step5: Poll on the Write In Progress (WIP) bit in Read Status Register
   do
   {
      NSSMD0   = 0;                    // Activate Slave Select
      SPI0DAT  = EEPROM_CMD_RDSR;      // Send the Read Status Register command
      while (!SPIF);                   // Wait for the command to be sent out
      SPIF     = 0;
      SPI0DAT  = 0;                    // Dummy write to output serial clock
      while (!SPIF);                   // Wait for the register to be read
      SPIF     = 0;
      NSSMD0   = 1;                    // Deactivate Slave Select after read
      Delay_us (1);
   } while( (SPI0DAT & 0x01) == 0x01 );
}

//-----------------------------------------------------------------------------
// EEPROM_Read
//-----------------------------------------------------------------------------
//
// Return Value : The value that was read from the EEPROM
//                   range: 0x00 to 0xFF
// Parameters   : 1. address - the source EEPROM address.
//                   range: 0 to EEPROM_CAPACITY
//
// Reads one byte from the specified EEPROM address.
//
//-----------------------------------------------------------------------------
BYTE EEPROM_Read (UINT address)
{
   // Reading a byte from the EEPROM is a three-step operation.
   
   // Step1: Send the READ command
   NSSMD0   = 0;                       // Activate Slave Select
   SPI0DAT  = EEPROM_CMD_READ;
   while (!SPIF);
   SPIF     = 0;
   
   // Step2: Send the EEPROM source address (MSB first)
   SPI0DAT  = (BYTE)((address >> 8) & 0x00FF);
   while (!SPIF);
   SPIF     = 0;
   SPI0DAT  = (BYTE)(address & 0x00FF);
   while (!SPIF);
   SPIF     = 0;
   
   // Step3: Read the value returned
   SPI0DAT  = 0;                       // Dummy write to output serial clock
   while (!SPIF);                      // Wait for the value to be read
   SPIF     = 0;
   NSSMD0   = 1;                       // Deactivate Slave Select
   Delay_us (1);
   
   return SPI0DAT;
}

//-----------------------------------------------------------------------------
// End Of File
//-----------------------------------------------------------------------------