ASURO Library: i2c.c Quellcode

00001 /****************************************************************************/
00018 /*****************************************************************************
00019 *                                                                            *
00020 *   This program is free software; you can redistribute it and/or modify     *
00021 *   it under the terms of the GNU General Public License as published by     *
00022 *   the Free Software Foundation; either version 2 of the License, or        *
00023 *   any later version.                                                       *
00024 *                                                                            *
00025 *****************************************************************************/
00026 #include "asuro.h"
00027 #include "i2c.h"
00028 
00029 
00030 
00031 /****************************************************************************/
00048 void InitI2C (void)
00049 {
00050   SDA_DDR |= (1 << SDA);        
00051   SCL_DDR |= (1 << SCL);        
00052   SDA_HI;             
00053   SCL_HI;             
00054 }
00055 
00056 
00057 
00058 /****************************************************************************/
00072 unsigned char WriteI2C (unsigned char byte)
00073 {
00074   unsigned char i;
00075   
00076   for (i=8; i>0; i--)
00077   {
00078     if ( byte & (1<<(i-1)) )
00079       SDA_HI;
00080     else
00081       SDA_LO;         
00082     SCL_TOGGLE;         
00083   }
00084   SDA_HI;             
00085 
00086   SDA_DDR &= ~(1 << SDA);
00087   HDEL;
00088   SCL_HI;
00089   byte = SDA_PIN & (1 << SDA);
00090 
00091   HDEL;
00092   SCL_LO;
00093   SDA_DDR |= (1 << SDA);
00094   HDEL;
00095 
00096   return (byte == 0);
00097 }
00098 
00099 
00100 
00101 /****************************************************************************/
00115 unsigned char ReadI2C(unsigned char ack)
00116 {
00117   unsigned char i, byte = 0;
00118   
00119   SDA_HI;
00120   SDA_DDR &= ~(1 << SDA);
00121   
00122   for (i=0; i<8; i++)
00123   {
00124   HDEL;
00125     SCL_HI;
00126     byte <<= 1;
00127     byte |= (SDA_PIN & (1 << SDA)) >> SDA;
00128     HDEL;
00129     SCL_LO;
00130   }
00131 
00132   SDA_DDR |= (1 << SDA);
00133 
00134   if (ack)
00135     SDA_LO;                             // ack
00136   else
00137     SDA_HI;                             // nak
00138 
00139   SCL_TOGGLE;
00140   SDA_HI;
00141 
00142   return byte;
00143 }
00144 
00145 
00146 
00147 /****************************************************************************/
00159 unsigned char StartI2C (unsigned char device)
00160 {
00161   I2C_START;
00162   return WriteI2C (device);
00163 }
00164 
00165 
00166 
00167 /****************************************************************************/
00179 void StopI2C (void)
00180 {
00181   SDA_LO;
00182   I2C_STOP;
00183 }