int i2c_stop() {
READSDA();
READSCL();
sda=-1;
scl=-1;
I2CSPEED=-1;
return 0;
}
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;
}
/* 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;
}
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;
}
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();
}
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;
}