inline int i2c_start(i2c_t *obj) {
int status = 0;
int isInterrupted = I2C_CONSET(obj) & (1 << 3);
// 8.1 Before master mode can be entered, I2CON must be initialised to:
// - I2EN STA STO SI AA - -
// - 1 0 0 x x - -
// if AA = 0, it can't enter slave mode
i2c_conclr(obj, 1, 1, 0, 1);
// The master mode may now be entered by setting the STA bit
// this will generate a start condition when the bus becomes free
i2c_conset(obj, 1, 0, 0, 1);
// Clearing SI bit when it wasn't set on entry can jump past state
// 0x10 or 0x08 and erroneously send uninitialized slave address.
if (isInterrupted)
i2c_clear_SI(obj);
i2c_wait_SI(obj);
status = i2c_status(obj);
// Clear start bit now that it's transmitted
i2c_conclr(obj, 1, 0, 0, 0);
return status;
}
// Wait until the Serial Interrupt (SI) is set
static int i2c_wait_SI(i2c_t *obj) {
int timeout = 0;
while (!(I2C_CONSET(obj) & (1 << 3))) {
timeout++;
if (timeout > 100000) return -1;
}
return 0;
}
inline void i2c_stop(i2c_t *obj) {
// write the stop bit
i2c_conset(obj, 0, 1, 0, 0);
i2c_clear_SI(obj);
// wait for STO bit to reset
while(I2C_CONSET(obj) & (1 << 4));
}
inline int i2c_stop(i2c_t *obj) {
int timeout = 0;
// write the stop bit
i2c_conset(obj, 0, 1, 0, 0);
i2c_clear_SI(obj);
// wait for STO bit to reset
while(I2C_CONSET(obj) & (1 << 4)) {
timeout ++;
if (timeout > 100000) return 1;
}
return 0;
}
static inline void i2c_interface_enable(i2c_t *obj) {
I2C_CONSET(obj) = 0x40;
}
static inline void i2c_conset(i2c_t *obj, int start, int stop, int interrupt, int acknowledge) {
I2C_CONSET(obj) = (start << 5)
| (stop << 4)
| (interrupt << 3)
| (acknowledge << 2);
}
