int i2c_slave_read(i2c_t *obj, char *data, int length) {
int count = 0;
int status;
do {
i2c_clear_SI(obj);
i2c_wait_SI(obj);
status = i2c_status(obj);
if((status == 0x80) || (status == 0x90)) {
data[count] = I2C_DAT(obj) & 0xFF;
}
count++;
} while (((status == 0x80) || (status == 0x90) ||
(status == 0x060) || (status == 0x70)) && (count < length));
// Clear old status and wait for Serial Interrupt.
i2c_clear_SI(obj);
i2c_wait_SI(obj);
// Obtain new status.
status = i2c_status(obj);
if(status != 0xA0) {
i2c_stop(obj);
}
i2c_clear_SI(obj);
return count;
}
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
int i, status;
status = i2c_start(obj);
if ((status != 0x10) && (status != 0x08)) {
i2c_stop(obj);
return status;
}
status = i2c_do_write(obj, (address & 0xFE), 1);
if (status != 0x18) {
i2c_stop(obj);
return status;
}
for (i=0; i<length; i++) {
status = i2c_do_write(obj, data[i], 0);
if(status != 0x28) {
i2c_stop(obj);
return status;
}
}
i2c_clear_SI(obj);
// If not repeated start, send stop.
if (stop) {
i2c_stop(obj);
}
return 0;
}
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;
}
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop) {
int i, status;
status = i2c_start(obj);
if ((status != 0x10) && (status != 0x08)) {
i2c_stop(obj);
return status;
}
status = i2c_do_write(obj, (address & 0xFE));
if (status != 0x18) {
i2c_stop(obj);
return status;
}
for (i=0; i<length; i++) {
status = i2c_do_write(obj, data[i]);
if(status != 0x28) {
i2c_stop(obj);
return status;
}
}
i2c_clear_SI(obj);
if (stop) {
if(i2c_stop(obj) == 1)
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));
}
static inline int i2c_do_write(i2c_t *obj, int value, uint8_t addr) {
// write the data
I2C_DAT(obj) = value;
// clear SI to init a send
i2c_clear_SI(obj);
// wait and return status
i2c_wait_SI(obj);
return i2c_status(obj);
}
int i2c_slave_read(i2c_t *obj, char *data, int length) {
int count = 0;
int status;
do {
i2c_clear_SI(obj);
i2c_wait_SI(obj);
status = i2c_status(obj);
if((status == 0x80) || (status == 0x90)) {
data[count] = I2C_DAT(obj) & 0xFF;
}
count++;
} while (((status == 0x80) || (status == 0x90) ||
(status == 0x060) || (status == 0x70)) && (count < length));
if(status != 0xA0) {
i2c_stop(obj);
}
i2c_clear_SI(obj);
return count;
}
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 int i2c_do_read(i2c_t *obj, int last) {
// we are in state 0x40 (SLA+R tx'd) or 0x50 (data rx'd and ack)
if(last) {
i2c_conclr(obj, 0, 0, 0, 1); // send a NOT ACK
} else {
i2c_conset(obj, 0, 0, 0, 1); // send a ACK
}
// accept byte
i2c_clear_SI(obj);
// wait for it to arrive
i2c_wait_SI(obj);
// return the data
return (I2C_DAT(obj) & 0xFF);
}
int i2c_slave_write(i2c_t *obj, const char *data, int length) {
int count = 0;
int status;
if(length <= 0) {
return(0);
}
do {
status = i2c_do_write(obj, data[count], 0);
count++;
} while ((count < length) && (status == 0xB8));
if ((status != 0xC0) && (status != 0xC8)) {
i2c_stop(obj);
}
i2c_clear_SI(obj);
return(count);
}