LUFA/Drivers/AT90USBXXX/SPI.h

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2009.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6       www.fourwalledcubicle.com
   7 */
   8
   9 /*
  10   Copyright 2009  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, and distribute this software
  13   and its documentation for any purpose and without fee is hereby
  14   granted, provided that the above copyright notice appear in all
  15   copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *
  33  *  Hardware SPI subsystem driver for the supported USB AVRs models.
  34  */
  35
  36 #ifndef __SPI_H__
  37 #define __SPI_H__
  38
  39         /* Includes: */
  40                 #include <stdbool.h>
  41
  42         /* Enable C linkage for C++ Compilers: */
  43                 #if defined(__cplusplus)
  44                         extern "C" {
  45                 #endif
  46
  47         /* Private Interface - For use in library only: */
  48         #if !defined(__DOXYGEN__)
  49                 /* Macros: */
  50                         #define SPI_USE_DOUBLESPEED            (1 << 7)
  51         #endif
  52
  53         /* Public Interface - May be used in end-application: */
  54                 /* Macros: */
  55                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 2. */
  56                         #define SPI_SPEED_FCPU_DIV_2           SPI_USE_DOUBLESPEED
  57
  58                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 4. */
  59                         #define SPI_SPEED_FCPU_DIV_4           0
  60
  61                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 8. */
  62                         #define SPI_SPEED_FCPU_DIV_8           (SPI_USE_DOUBLESPEED | (1 << SPR0))
  63
  64                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 16. */
  65                         #define SPI_SPEED_FCPU_DIV_16          (1 << SPR0)
  66
  67                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 32. */
  68                         #define SPI_SPEED_FCPU_DIV_32          (SPI_USE_DOUBLESPEED | (1 << SPR1))
  69
  70                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 64. */
  71                         #define SPI_SPEED_FCPU_DIV_64          (SPI_USE_DOUBLESPEED | (1 << SPR1) | (1 << SPR0))
  72
  73                         /** SPI prescaler mask for SPI_Init(). Divides the system clock by a factor of 128. */
  74                         #define SPI_SPEED_FCPU_DIV_128         ((1 << SPR1) | (1 << SPR0))
  75
  76                 /* Inline Functions: */
  77                         /** Initializes the SPI subsystem, ready for transfers. Must be called before calling any other
  78                          *  SPI routines.
  79                          *
  80                          *  \param PrescalerMask  Prescaler mask to set the SPI clock speed
  81                          *  \param Master         If true, sets the SPI system to use master mode, slave if false
  82                          */
  83                         static inline void SPI_Init(const uint8_t PrescalerMask, const bool Master)
  84                         {
  85                                 DDRB  |= ((1 << 1) | (1 << 2));
  86                                 PORTB |= ((1 << 0) | (1 << 3));
  87
  88                                 SPCR   = ((1 << SPE) | (Master << MSTR) | (1 << CPOL) | (1 << CPHA) |
  89                                           (PrescalerMask & ~SPI_USE_DOUBLESPEED));
  90
  91                                 if (PrescalerMask & SPI_USE_DOUBLESPEED)
  92                                   SPSR = (1 << SPI2X);
  93                         }
  94
  95                         /** Sends and receives a byte through the SPI interface, blocking until the transfer is complete.
  96                          *
  97                          *  \param Byte  Byte to send through the SPI interface
  98                          *
  99                          *  \return Response byte from the attached SPI device
 100                          */
 101                         static inline uint8_t SPI_TransferByte(const uint8_t Byte) ATTR_ALWAYS_INLINE;
 102                         static inline uint8_t SPI_TransferByte(const uint8_t Byte)
 103                         {
 104                                 SPDR = Byte;
 105                                 while (!(SPSR & (1 << SPIF)));
 106                                 return SPDR;
 107                         }
 108
 109                         /** Sends a byte through the SPI interface, blocking until the transfer is complete. The response
 110                          *  byte sent to from the attached SPI device is ignored.
 111                          *
 112                          *  \param Byte Byte to send through the SPI interface
 113                          */
 114                         static inline void SPI_SendByte(const uint8_t Byte) ATTR_ALWAYS_INLINE;
 115                         static inline void SPI_SendByte(const uint8_t Byte)
 116                         {
 117                                 SPDR = Byte;
 118                                 while (!(SPSR & (1 << SPIF)));
 119                         }
 120
 121                         /** Sends a dummy byte through the SPI interface, blocking until the transfer is complete. The response
 122                          *  byte from the attached SPI device is returned.
 123                          *
 124                          *  \return The response byte from the attached SPI device
 125                          */
 126                         static inline uint8_t SPI_ReceiveByte(void) ATTR_ALWAYS_INLINE ATTR_WARN_UNUSED_RESULT;
 127                         static inline uint8_t SPI_ReceiveByte(void)
 128                         {
 129                                 SPDR = 0x00;
 130                                 while (!(SPSR & (1 << SPIF)));
 131                                 return SPDR;
 132                         }
 133
 134         /* Disable C linkage for C++ Compilers: */
 135                 #if defined(__cplusplus)
 136                         }
 137                 #endif
 138
 139 #endif