unsigned char I2C_ReadBit_Wait()
{
SDAINPUT;
I2C_CLOCK_HI();
unsigned int i = 0;
unsigned char c = READSDA;
while(c>0 && i<=35)
{
I2CDELAY(1);
c = READSDA;
i++;
}
if(c)
I2C_DATA_HI();
else
I2C_DATA_LO();
SDAOUTPUT;
I2CDELAY(1);
I2C_CLOCK_LO();
I2CDELAY(1);
return c?0:1; // return true on ACK (0)
}
//! Send a START Condition
void I2C_Start()
{
I2C_Take(); // XXX Should probably check to see if someone else is using the bus before we do this
I2CDELAY(3);
I2C_DATA_LO();
I2CDELAY(3);
I2C_CLOCK_LO();
I2CDELAY(1);
}
//! Send a STOP Condition
void I2C_Stop()
{
I2C_DATA_LO();
I2CDELAY(3);
I2C_CLOCK_HI();
I2CDELAY(3);
I2C_DATA_HI();
I2CDELAY(1);
I2C_Release();
}
//! 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);
}
static void stop_cond(void) {
/* Pull SDA down */
CLRSDA();
I2CDELAY(I2CSPEED/2);
/* Clock stretching - wait for slave to raise it*/
while (READSCL() == 0);
/* SCL is high, set SDA from 0 to 1 */
if (READSDA() == 0) {
ARBITRATION_LOST();
}
I2CDELAY(I2CSPEED/2);
start = 0;
}
static unsigned char read_bit(void) {
unsigned char bit;
// Let the slave drive data
READSDA();
I2CDELAY(I2CSPEED/2);
/* Clock stretching */
while (READSCL() == 0);
/* SCL is high, now data is valid */
bit = READSDA();
I2CDELAY(I2CSPEED/2);
CLRSCL();
return bit;
}
bool stop_cond(void)
{
/* set SDA to 0 */
CLRSDA();
I2CDELAY(I2CSPEED/2);
/* Clock stretching */
while (READSCL() == 0);
/* SCL is high, set SDA from 0 to 1 */
if (READSDA() == 0)
return false; //arbitration lost
I2CDELAY(I2CSPEED/2);
start = 0;
return true;
}
bool read_bit(void)
{
bool bit;
//Let slave drive data signal.
READSDA();
I2CDELAY(I2CSPEED/2);
/* Clock stretching */
while (READSCL() == 0);
/* SCL is high, now data is valid */
bit = READSDA();
I2CDELAY(I2CSPEED/2);
CLRSCL();
return bit;
}
void i2c_stop_cond(void)
{
/* set SDA to 0 */
CLRSDA();
I2CDELAY();
/* Clock stretching */
while (READSCL() == 0)
; /* You should add timeout to this loop */
/* SCL is high. Respect I2C spec's minimum stop setup time of 4ms. */
I2CDELAY();
/* set SDA from 0 to 1 */
if (READSDA() == 0)
ARBITRATION_LOST();
I2CDELAY();
started = false;
}
/* Read a bit from I2C bus */
static int i2c_read_bit(void)
{
int bit;
/* Let the slave drive data */
READSDA();
I2CDELAY();
/* Clock stretching */
while (READSCL() == 0)
; /* You should add timeout to this loop */
/* SCL is high, now data is valid */
bit = READSDA();
I2CDELAY();
CLRSCL();
return bit;
}
bool write_bit(bool bit)
{
if(bit)
READSDA();
else
CLRSDA();
I2CDELAY(I2CSPEED/2);
/* Clock stretching */
while (READSCL() == 0);
/* SCL is high, now data is valid */
/* check that nobody is driving SDA */
if (bit && READSDA() == 0)
return false; //arbitration lost
I2CDELAY(I2CSPEED/2);
CLRSCL();
return true;
}
/* Write a bit to I2C bus */
static void i2c_write_bit(int bit)
{
if (bit)
READSDA();
else
CLRSDA();
I2CDELAY();
/* Clock stretching */
while (READSCL() == 0)
; /* You should add timeout to this loop */
/* SCL is high, now data is valid */
/* If SDA is high, check that nobody else is driving SDA */
if (bit && READSDA() == 0)
ARBITRATION_LOST();
I2CDELAY();
CLRSCL();
}
//! Read an I2C bit.
unsigned char I2C_ReadBit()
{
SDAINPUT;
I2C_CLOCK_HI();
unsigned char c = READSDA;
if(c)
I2C_DATA_HI();
else
I2C_DATA_LO();
SDAOUTPUT;
I2CDELAY(1);
I2C_CLOCK_LO();
I2CDELAY(1);
return c;
}
static void start_cond(void) {
if (start) {
/* Let SDA rise */
READSDA();
I2CDELAY(I2CSPEED/2);
/* Clock stretching */
while (READSCL() == 0);
}
if (READSDA() == 0) {
ARBITRATION_LOST();
}
/* SCL is high, we waited for slave to raise it, so pull SDA down */
CLRSDA();
I2CDELAY(I2CSPEED/2);
// Now pull SCL down
CLRSCL();
start = 1;
}
static void write_bit(unsigned char bit) {
//Put the bit on SDA by either letting it rise or pulling it down
if (bit) {
READSDA();
} else {
CLRSDA();
}
I2CDELAY(I2CSPEED/2);
/* Clock stretching - Let SCL rise and wait for slave to let it rise */
while (READSCL() == 0);
/* SCL is high, now data is being read */
/* If SDA is high, check that nobody else is driving SDA */
if (bit) {
if (READSDA() == 0) { //Oops, someone else pulled SDA down
ARBITRATION_LOST();
}
}
I2CDELAY(I2CSPEED/2);
CLRSCL();
}
void i2c_start_cond(void)
{
if (started) {
// if started, do a restart cond
// set SDA to 1
READSDA();
I2CDELAY();
// Clock stretching
while (READSCL() == 0)
; // You can add a timeout to this loop to
// recover from SCL being stuck low.
// Repeated start setup time, minimum 4.7us
I2CDELAY();
}
if (READSDA() == 0)
ARBITRATION_LOST();
// SCL is high, set SDA from 1 to 0
CLRSDA();
I2CDELAY();
CLRSCL();
started = true;
}
//! 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;
}
//! Inits bitbanging port, must be called before using the functions below
void I2C_Init()
{
I2C_Take();
//PULLON;
I2CDELAY(1);
}
//! Handles an i2c command.
void i2c_handle_fn( uint8_t const app,
uint8_t const verb,
uint32_t const len)
{
unsigned char i;
unsigned long l;
switch(verb)
{
case READ:
l = len;
if(l > 0) //optional parameter of length
l=cmddata[0];
if(!l) //default value of 1
l=1;
I2C_Start();
for(i=0; i < l; i++)
cmddata[i]=I2C_Read(i<l?1:0);
I2C_Stop();
txdata(app,verb,l);
break;
case WRITE:
I2C_Start();
cmddata[0] = cmddata[0] << 1;
for(i=0; i<len; i++) {
if (!I2C_Write(cmddata[i])) //if NACK
break;
}
I2C_Stop();
cmddata[0] = i;
txdata(app,verb,1);
break;
case PEEK:
l = cmddata[0];
I2C_Start();
unsigned char address = cmddata[1] << 1;
I2C_Write(address);
for(i=2; i < len; i++){
I2C_Write(cmddata[i]);
}
I2C_Start();
I2C_Write(address|1); // spit out the target address again and flip the read bit
I2CDELAY(1); // XXX We should wait for clock to go high here XXX
for(i=0; i < l; i++)
cmddata[i]=I2C_Read(i+1<l?1:0); // If the next i is still less than l, then ACK
I2C_Stop();
txdata(app,verb,l);
break;
case POKE:
break;
case START:
I2C_Start();
txdata(app,verb,0);
break;
case STOP:
I2C_Stop();
txdata(app,verb,0);
break;
case SETUP:
I2C_Init();
txdata(app,verb,0);
break;
}
}
