I2C committed but not tested.

[goodfet] / firmware / apps / i2c / i2c.c

diff --git a/firmware/apps/i2c/i2c.c b/firmware/apps/i2c/i2c.c
new file mode 100644 (file)
index 0000000..1f92b9e
--- /dev/null
+++ b/firmware/apps/i2c/i2c.c
@@ -0,0 +1,186 @@
+//GoodFET I2C Master Application
+//Handles basic I/O
+
+//Higher level left to client application.
+
+//Based upon a neighborly example at
+//http://codinglab.blogspot.com/2008/10/i2c-on-avr-using-bit-banging.html
+
+#include "platform.h"
+#include "command.h"
+
+#include <signal.h>
+#include <io.h>
+#include <iomacros.h>
+
+
+//Pins and I/O
+#define SS   BIT3
+#define SDA  BIT2
+#define SCL  BIT3
+
+#define I2CDELAY(x) delay(x)
+
+//Bits are cleared by output of low.
+//Bits are set but input and pull-up resistor.
+#define SETSDA P5DIR&=~SDA
+#define CLRSDA P5DIR|=SDA
+#define SETSCL P5DIR&=~SCL
+#define CLRSCL P5DIR|=SCL
+
+#define READSDA (P5IN&SDA?1:0)
+#define SETBOTH P5DIR&=~(SDA|SCL)
+
+#define I2C_DATA_HI() SETSDA
+#define I2C_DATA_LO() CLRSDA
+
+#define I2C_CLOCK_HI() SETSCL
+#define I2C_CLOCK_LO() CLRSCL
+
+//! Write an I2C bit.
+void I2C_WriteBit( unsigned char c )
+{
+  if(c>0)
+    I2C_DATA_HI();
+  else
+    I2C_DATA_LO();
+
+  I2C_CLOCK_HI();
+  I2CDELAY(1);
+
+  I2C_CLOCK_LO();
+  I2CDELAY(1);
+
+  if(c>0)
+    I2C_DATA_LO();
+
+  I2CDELAY(1);
+}
+
+//! Read an I2C bit.
+unsigned char I2C_ReadBit()
+{
+  I2C_DATA_HI();
+
+  I2C_CLOCK_HI();
+  I2CDELAY(1);
+
+  unsigned char c = READSDA;
+
+  I2C_CLOCK_LO();
+  I2CDELAY(1);
+
+  return c;
+}
+
+//! Inits bitbanging port, must be called before using the functions below
+void I2C_Init()
+{
+  //Clear SDA and SCL.
+  //Direction, not value, is used to set the value.
+  //(Pull-up or 0.)
+  P5OUT&=~(SDA|SCL);
+  
+  I2C_CLOCK_HI();
+  I2C_DATA_HI();
+
+  I2CDELAY(1);
+}
+
+//! Send a START Condition
+void I2C_Start()
+{
+  // set both to high at the same time
+  SETBOTH;
+  I2CDELAY(1);
+  
+  I2C_DATA_LO();
+  I2CDELAY(1);
+  
+  I2C_CLOCK_LO();
+  I2CDELAY(1);
+}
+
+//! Send a STOP Condition
+void I2C_Stop()
+{
+  I2C_CLOCK_HI();
+  I2CDELAY(1);
+
+  I2C_DATA_HI();
+  I2CDELAY(1);
+}
+
+//! write a byte to the I2C slave device
+unsigned char I2C_Write( unsigned char c )
+{
+  char i;
+  for (i=0;i<8;i++){
+    I2C_WriteBit( c & 128 );
+    c<<=1;
+  }
+  
+  return I2C_ReadBit();
+}
+
+
+//! read a byte from the I2C slave device
+unsigned char I2C_Read( unsigned char ack )
+{
+  unsigned char res = 0;
+  char i;
+  
+  for (i=0;i<8;i++){
+    res <<= 1;
+    res |= I2C_ReadBit();  
+  }
+  
+  if( ack > 0)
+    I2C_WriteBit(0);
+  else
+    I2C_WriteBit(1);
+  
+  I2CDELAY(1);
+  
+  return res;
+}
+
+
+//! Handles a monitor command.
+void i2chandle(unsigned char app,
+              unsigned char verb,
+              unsigned char len){
+  unsigned char i;
+  switch(verb){
+    
+  case PEEK:
+    break;
+  case POKE:
+    break;
+    
+  case READ:
+    if(len>0)          //optional parameter of length
+      len=cmddata[0];
+    if(len==0)         //default value of 1
+      len=1;
+    for(i=0;i<len;i++)
+      cmddata[i]=I2C_Read(1);  //Always acknowledge
+    txdata(app,verb,len);
+    break;
+  case WRITE:
+    for(i=0;i<len;i++)
+      I2C_Write(cmddata[i]);
+    txdata(app,verb,0);
+    break;
+  case START:
+    I2C_Start();
+    break;
+  case STOP:
+    I2C_Stop();
+    break;
+  case SETUP:
+    I2C_Init();
+    txdata(app,verb,0);
+    break;
+  }
+}