/***************************************************************************
 *   Copyright (C) 2008, Crawlerz                                          *
 *                                                                         *
 *   Description:                                                          *
 *     Low-level Software SPI Master (SPIM) "C" code snippets for:         *
 *        - Unigen's Juno M & Juno W RF Modules                            *
 *        - Cypress CYWM6934 & CYWM6935 RF Modules                         *
 *        - Cypress CYWUSB6932, CYWUSB6934, and CYWUSB6935                 *
 *   Version:                                                              *
 *     2008.35.2                                                           *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/

// physical interface
#define SCK          PB0
#define SCK_LO       SCK = 0
#define SCK_HI       SCK = 1
#define MISO         PB1
#define MOSI         PB2
#define MOSI_LO      MOSI = 0
#define MOSI_HI      MOSI = 1
#define nSS          PB3
#define nSS_LO       nSS = 0
#define nSS_HI       nSS = 1
#define IRQ          PB6
#define nPD          PB7
#define nPD_LO       nPD = 0
#define nPD_HI       nPD = 1

#define nRST      PB4
#define nRST_LO   nRST = 0
#define nRST_HI   nRST = 1
#define X13OUT    PB5

#define SPI_WR    0x80
#define SPI_RD    0x00
#define SPI_INC   0x40
#define SPI_FRZ   0x00

// prototypes for spi routines
BYTE SpiRead(BYTE addr);
void SpiWrite(BYTE addr, BYTE dat);
void SpiFileRead(BYTE addr, BYTE len, BYTE *dest);
void SpiFileWrite(BYTE addr, BYTE len, BYTE *src);

BYTE SpiRead(BYTE addr)
{
   B = addr;
   nSS_LO;
   // write cmd bits + addr
   MOSI_LO;   SCK_HI; SCK_LO;
   MOSI_LO;   SCK_HI; SCK_LO;
   MOSI = B5; SCK_HI; SCK_LO;
   MOSI = B4; SCK_HI; SCK_LO;
   MOSI = B3; SCK_HI; SCK_LO;
   MOSI = B2; SCK_HI; SCK_LO;
   MOSI = B1; SCK_HI; SCK_LO;
   MOSI = B0; SCK_HI; SCK_LO;
   //read data
   SCK_HI; B7 = MISO; SCK_LO;
   SCK_HI; B6 = MISO; SCK_LO;
   SCK_HI; B5 = MISO; SCK_LO;
   SCK_HI; B4 = MISO; SCK_LO;
   SCK_HI; B3 = MISO; SCK_LO;
   SCK_HI; B2 = MISO; SCK_LO;
   SCK_HI; B1 = MISO; SCK_LO;
   SCK_HI; B0 = MISO; SCK_LO;
   nSS_HI;

   return(B);
}

void SpiWrite(BYTE addr, BYTE dat)
{
   B = addr;
   nSS_LO;
   // write cmd bits + addr
   MOSI_HI;   SCK_HI; SCK_LO;
   MOSI_LO;   SCK_HI; SCK_LO;
   MOSI = B5; SCK_HI; SCK_LO;
   MOSI = B4; SCK_HI; SCK_LO;
   MOSI = B3; SCK_HI; SCK_LO;
   MOSI = B2; SCK_HI; SCK_LO;
   MOSI = B1; SCK_HI; SCK_LO;
   MOSI = B0; SCK_HI; SCK_LO;
   // data phase
   B = dat;
   MOSI = B7; SCK_HI; SCK_LO;
   MOSI = B6; SCK_HI; SCK_LO;
   MOSI = B5; SCK_HI; SCK_LO;
   MOSI = B4; SCK_HI; SCK_LO;
   MOSI = B3; SCK_HI; SCK_LO;
   MOSI = B2; SCK_HI; SCK_LO;
   MOSI = B1; SCK_HI; SCK_LO;
   MOSI = B0; SCK_HI; SCK_LO;
   nSS_HI;
}

// NOTE
// The code generated for a generic pointer executes more slowly than the
// equivalent code generated for a memory-specific pointer because the memory
// area is not known until run-time. The compiler cannot optimize memory
// accesses and must generate generic code that can access any memory area. If
// execution speed is a priority, you should use memory-specific pointers instead of
// generic pointers wherever possible.

void SpiFileRead(BYTE addr, BYTE len, BYTE *dest)
{
   BYTE i;

   B = addr;
   nSS_LO;
   // write cmd bits + addr
   MOSI_LO;   SCK_HI; SCK_LO; // dir=0 (bus read operation) 
   MOSI = B6; SCK_HI; SCK_LO; // 1=inc or 0=frz
   MOSI = B5; SCK_HI; SCK_LO;
   MOSI = B4; SCK_HI; SCK_LO;
   MOSI = B3; SCK_HI; SCK_LO;
   MOSI = B2; SCK_HI; SCK_LO;
   MOSI = B1; SCK_HI; SCK_LO;
   MOSI = B0; SCK_HI; SCK_LO;
   // data phase
   for(i=0;i<len;i++,dest++) {
      SCK_HI; _nop_(); B7 = MISO; SCK_LO; // nop handles every 9th clock HI stretch
      SCK_HI; B6 = MISO; SCK_LO;
      SCK_HI; B5 = MISO; SCK_LO;
      SCK_HI; B4 = MISO; SCK_LO;
      SCK_HI; B3 = MISO; SCK_LO;
      SCK_HI; B2 = MISO; SCK_LO;
      SCK_HI; B1 = MISO; SCK_LO;
      SCK_HI; B0 = MISO; SCK_LO;
      *(BYTE *)dest = B;
   }
   nSS_HI;
}

// NOTE
// The code generated for a generic pointer executes more slowly than the
// equivalent code generated for a memory-specific pointer because the memory
// area is not known until run-time. The compiler cannot optimize memory
// accesses and must generate generic code that can access any memory area. If
// execution speed is a priority, you should use memory-specific pointers instead of
// generic pointers wherever possible.

void SpiFileWrite(BYTE addr, BYTE len, BYTE *src)
{
   BYTE i;

   B = addr;
   nSS_LO;
   // write cmd bits + addr
   MOSI_HI;   SCK_HI; SCK_LO;  // dir=1 (bus write operation)
   MOSI = B6; SCK_HI; SCK_LO;  // 1=inc or 0=freeze
   MOSI = B5; SCK_HI; SCK_LO;
   MOSI = B4; SCK_HI; SCK_LO;
   MOSI = B3; SCK_HI; SCK_LO;
   MOSI = B2; SCK_HI; SCK_LO;
   MOSI = B1; SCK_HI; SCK_LO;
   MOSI = B0; SCK_HI; SCK_LO;

   // data phase
   for(i=0;i<len;i++,src++) {
      B = *(BYTE *)src;
      MOSI = B7; SCK_HI; SCK_LO;
      MOSI = B6; SCK_HI; SCK_LO;
      MOSI = B5; SCK_HI; SCK_LO;
      MOSI = B4; SCK_HI; SCK_LO;
      MOSI = B3; SCK_HI; SCK_LO;
      MOSI = B2; SCK_HI; SCK_LO;
      MOSI = B1; SCK_HI; SCK_LO;
      MOSI = B0; SCK_HI; SCK_LO;
   }
   nSS_HI;
}