//! Combined i2c send+receive format
status_t
i2c_send_receive(const i2c_bus *bus, int slaveAddress, const uint8 *writeBuffer,
size_t writeLength, uint8 *readBuffer, size_t readLength)
{
status_t status = send_start_condition(bus);
if (status != B_OK)
return status;
status = send_slave_address(bus, slaveAddress, true);
if (status != B_OK)
goto err;
status = send_bytes(bus, writeBuffer, writeLength);
if (status != B_OK)
goto err;
status = send_start_condition(bus);
if (status != B_OK)
return status;
status = send_slave_address(bus, slaveAddress, false);
if (status != B_OK)
goto err;
status = receive_bytes(bus, readBuffer, readLength);
if (status != B_OK)
goto err;
return send_stop_condition(bus);
err:
TRACE("%s: Cancelling transmission\n", __func__);
send_stop_condition(bus);
return status;
}
static void handle_tw_status(struct twi_transfer *xfer, uint8_t twstat)
{
uint8_t *buffer = xfer->buffer;
switch (twstat) {
default:
stop_transfer(xfer, TWI_STAT_BUSERROR);
break;
case TW_START:
case TW_REP_START:
if (xfer->status & TWI_XFER_READ)
TWDR = (xfer->address << 1) | 1;
else
TWDR = (xfer->address << 1);
TWCR_write(1 << TWIE);
break;
case TW_MT_DATA_ACK:
case TW_MR_DATA_ACK:
case TW_MR_DATA_NACK:
case TW_MT_SLA_ACK:
if (xfer->status & TWI_XFER_READ) {
buffer[xfer->offset++] = TWDR;
if (xfer->offset == xfer->read_size) {
stop_transfer(xfer, TWI_STAT_FINISHED);
} else {
if (xfer->offset + 1 == xfer->read_size)
TWCR_write(1 << TWIE);
else
TWCR_write((1 << TWIE) | (1 << TWEA));
}
} else {
if (xfer->offset == xfer->write_size) {
if (xfer->read_size) {
xfer->status |= TWI_XFER_READ;
xfer->offset = 0;
send_start_condition();
} else
stop_transfer(xfer, TWI_STAT_FINISHED);
} else {
TWDR = buffer[xfer->offset++];
TWCR_write(1 << TWIE);
}
}
break;
case TW_MR_SLA_ACK:
if (xfer->offset + 1 == xfer->read_size)
TWCR_write(1 << TWIE);
else
TWCR_write((1 << TWIE) | (1 << TWEA));
break;
}
}
void twi_transfer(struct twi_transfer *xfer)
{
#ifdef TWI_SYNC
twi_size_t i;
uint8_t *buffer = xfer->buffer;
if (xfer->write_size) {
i2c_start(xfer->address << 1);
for (i = 0; i < xfer->write_size; i++)
i2c_write(buffer[i]);
if (!xfer->read_size)
i2c_stop();
}
if (xfer->read_size) {
i2c_start((xfer->address << 1) | 1);
for (i = 0; i < xfer->read_size; i++) {
if (i + 1 == xfer->read_size)
buffer[i] = i2c_readNak();
else
buffer[i] = i2c_readAck();
}
i2c_stop();
}
if (xfer->callback)
xfer->callback(xfer, TWI_STAT_FINISHED);
#else /* TWI_SYNC */
uint8_t sreg;
xfer->offset = 0;
xfer->next = NULL;
xfer->status = 0;
if (!xfer->write_size)
xfer->status |= TWI_XFER_READ;
transfer_set_status(xfer, TWI_STAT_INPROGRESS);
sreg = irq_disable_save();
if (twi.last_xfer)
twi.last_xfer->next = xfer;
twi.last_xfer = xfer;
if (!twi.first_xfer) {
twi.first_xfer = xfer;
send_start_condition();
}
irq_restore(sreg);
#endif
}
static void stop_transfer(struct twi_transfer *xfer,
enum twi_status new_status)
{
send_stop_condition();
transfer_set_status(xfer, new_status);
twi.first_xfer = xfer->next;
if (twi.first_xfer)
send_start_condition();
else
twi.last_xfer = NULL;
if (xfer->callback)
xfer->callback(xfer, new_status);
}
