/**
* \brief Writes a packet to the master
*
* Writes a packet to the master. This will wait for the master to issue
* a request.
*
* \param[in] module Pointer to software module structure
* \param[in] packet Packet to write to master
*
* \return Status of packet write.
* \retval STATUS_OK Packet was written successfully
* \retval STATUS_ERR_DENIED Start condition not received, another
* interrupt flag is set
* \retval STATUS_ERR_IO There was an error in the previous transfer
* \retval STATUS_ERR_BAD_FORMAT Master wants to write data
* \retval STATUS_ERR_INVALID_ARG Invalid argument(s) was provided
* \retval STATUS_ERR_BUSY The I<SUP>2</SUP>C module is busy with a job
* \retval STATUS_ERR_ERR_OVERFLOW Master NACKed before entire packet was
* transferred
* \retval STATUS_ERR_TIMEOUT No response was given within the timeout
* period
*/
enum status_code i2c_slave_write_packet_wait(
struct i2c_slave_module *const module,
struct i2c_slave_packet *const packet)
{
/* Sanity check arguments */
Assert(module);
Assert(module->hw);
Assert(packet);
SercomI2cs *const i2c_hw = &(module->hw->I2CS);
uint16_t length = packet->data_length;
if (length == 0) {
return STATUS_ERR_INVALID_ARG;
}
#if I2C_SLAVE_CALLBACK_MODE == true
/* Check if the module is busy with a job or AMATCH is enabled */
if (module->buffer_remaining > 0 ||
(i2c_hw->INTENSET.reg & SERCOM_I2CS_INTFLAG_AMATCH)) {
return STATUS_BUSY;
}
#endif
enum status_code status;
/* Wait for master to send address packet */
status = _i2c_slave_wait_for_bus(module);
if (status != STATUS_OK) {
/* Timeout, return */
return status;
}
if (!(i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_AMATCH)) {
/* Not address interrupt, something is wrong */
return STATUS_ERR_DENIED;
}
if (module->ten_bit_address) {
/* ACK the first address */
i2c_hw->CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
/* Wait for address interrupt */
status = _i2c_slave_wait_for_bus(module);
if (status != STATUS_OK) {
/* Timeout, return */
return STATUS_ERR_TIMEOUT;
}
if (!(i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_AMATCH)) {
/* Not address interrupt, something is wrong */
return STATUS_ERR_DENIED;
}
}
/* Check if there was an error in last transfer */
if (i2c_hw->STATUS.reg & (SERCOM_I2CS_STATUS_BUSERR |
SERCOM_I2CS_STATUS_COLL | SERCOM_I2CS_STATUS_LOWTOUT)) {
return STATUS_ERR_IO;
}
/* Check direction */
if (!(i2c_hw->STATUS.reg & SERCOM_I2CS_STATUS_DIR)) {
/* Write request from master, send NACK and return */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
return STATUS_ERR_BAD_FORMAT;
}
/* Read request from master, ACK address */
i2c_hw->CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
uint16_t i = 0;
/* Wait for data interrupt */
status = _i2c_slave_wait_for_bus(module);
if (status != STATUS_OK) {
/* Timeout, return */
return status;
}
while (length--) {
/* Write data */
_i2c_slave_wait_for_sync(module);
i2c_hw->DATA.reg = packet->data[i++];
/* Wait for response from master */
status = _i2c_slave_wait_for_bus(module);
if (status != STATUS_OK) {
/* Timeout, return */
return status;
}
if (i2c_hw->STATUS.reg & SERCOM_I2CS_STATUS_RXNACK &&
length !=0) {
/* NACK from master, abort */
/* Release line */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x02);
return STATUS_ERR_OVERFLOW;
}
/* ACK from master, continue writing */
}
/* Release line */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x02);
return STATUS_OK;
}
/**
* \brief Reads a packet from the master
*
* Reads a packet from the master. This will wait for the master to issue a
* request.
*
* \param[in] module Pointer to software module structure
* \param[out] packet Packet to read from master
*
* \return Status of packet read.
* \retval STATUS_OK Packet was read successfully
* \retval STATUS_ABORTED Master sent stop condition or repeated
* start before specified length of bytes
* was received
* \retval STATUS_ERR_IO There was an error in the previous transfer
* \retval STATUS_ERR_DENIED Start condition not received, another
* interrupt flag is set
* \retval STATUS_ERR_INVALID_ARG Invalid argument(s) was provided
* \retval STATUS_ERR_BUSY The I<SUP>2</SUP>C module is busy with a job
* \retval STATUS_ERR_BAD_FORMAT Master wants to read data
* \retval STATUS_ERR_ERR_OVERFLOW Last byte received overflows buffer
*/
enum status_code i2c_slave_read_packet_wait(
struct i2c_slave_module *const module,
struct i2c_slave_packet *const packet)
{
/* Sanity check arguments */
Assert(module);
Assert(module->hw);
Assert(packet);
SercomI2cs *const i2c_hw = &(module->hw->I2CS);
uint16_t length = packet->data_length;
if (length == 0) {
return STATUS_ERR_INVALID_ARG;
}
#if I2C_SLAVE_CALLBACK_MODE == true
/* Check if the module is busy with a job or AMATCH is enabled */
if (module->buffer_remaining > 0 ||
(i2c_hw->INTENSET.reg & SERCOM_I2CS_INTFLAG_AMATCH)) {
return STATUS_BUSY;
}
#endif
enum status_code status;
/* Wait for master to send address packet */
status = _i2c_slave_wait_for_bus(module);
if (status != STATUS_OK) {
/* Timeout, return */
return status;
}
if (!(i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_AMATCH)) {
/* Not address interrupt, something is wrong */
return STATUS_ERR_DENIED;
}
/* Check if there was an error in the last transfer */
if (i2c_hw->STATUS.reg & (SERCOM_I2CS_STATUS_BUSERR |
SERCOM_I2CS_STATUS_COLL | SERCOM_I2CS_STATUS_LOWTOUT)) {
return STATUS_ERR_IO;
}
/* Check direction */
if ((i2c_hw->STATUS.reg & SERCOM_I2CS_STATUS_DIR)) {
/* Read request from master, send NACK and return */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
return STATUS_ERR_BAD_FORMAT;
}
/* Write request from master, ACK address */
i2c_hw->CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
uint16_t i = 0;
while (length--) {
/* Wait for next byte or stop condition */
status = _i2c_slave_wait_for_bus(module);
if (status != STATUS_OK) {
/* Timeout, return */
return status;
}
if ((i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_PREC) ||
i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_AMATCH) {
/* Master sent stop condition, or repeated start, read done */
/* Clear stop flag */
i2c_hw->INTFLAG.reg = SERCOM_I2CS_INTFLAG_PREC;
return STATUS_ABORTED;
}
/* Read data */
_i2c_slave_wait_for_sync(module);
packet->data[i++] = i2c_hw->DATA.reg;
}
/* Packet read done, wait for packet to NACK, Stop or repeated start */
status = _i2c_slave_wait_for_bus(module);
if (i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_DRDY) {
/* Buffer is full, send NACK */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x2);
}
if (i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_PREC) {
/* Clear stop flag */
i2c_hw->INTFLAG.reg = SERCOM_I2CS_INTFLAG_PREC;
}
return STATUS_OK;
}
/**
* \internal Interrupt handler for I<SUP>2</SUP>C slave
*
* \param[in] instance Sercom instance that triggered the interrupt
*/
void _i2c_slave_interrupt_handler(
uint8_t instance)
{
/* Get software module for callback handling. */
struct i2c_slave_module *module =
(struct i2c_slave_module*)_sercom_instances[instance];
Assert(module);
SercomI2cs *const i2c_hw = &(module->hw->I2CS);
/* Combine callback registered and enabled masks. */
uint8_t callback_mask =
module->enabled_callback & module->registered_callback;
if (i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_AMATCH) {
/* Address match */
/* Check if last transfer is done - repeated start */
if (module->buffer_length != module->buffer_remaining &&
module->transfer_direction == I2C_TRANSFER_WRITE) {
module->status = STATUS_OK;
module->buffer_length = 0;
module->buffer_remaining = 0;
if ((callback_mask & (1 << I2C_SLAVE_CALLBACK_READ_COMPLETE))) {
module->callbacks[I2C_SLAVE_CALLBACK_READ_COMPLETE](module);
}
} else if (module->buffer_length != module->buffer_remaining &&
module->transfer_direction == I2C_TRANSFER_READ) {
module->status = STATUS_OK;
module->buffer_length = 0;
module->buffer_remaining = 0;
if ((callback_mask & (1 << I2C_SLAVE_CALLBACK_WRITE_COMPLETE))) {
module->callbacks[I2C_SLAVE_CALLBACK_WRITE_COMPLETE](module);
}
}
if (i2c_hw->STATUS.reg & (SERCOM_I2CS_STATUS_BUSERR ||
SERCOM_I2CS_STATUS_COLL || SERCOM_I2CS_STATUS_LOWTOUT)) {
/* An error occurred in last packet transfer */
module->status = STATUS_ERR_IO;
if ((callback_mask & (1 << I2C_SLAVE_CALLBACK_ERROR_LAST_TRANSFER))) {
module->callbacks[I2C_SLAVE_CALLBACK_ERROR_LAST_TRANSFER](module);
}
}
if (module->nack_on_address) {
/* NACK address */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
} else if (i2c_hw->STATUS.reg & SERCOM_I2CS_STATUS_DIR) {
/* Set transfer direction in module instance */
module->transfer_direction = I2C_TRANSFER_READ;
/* Read request from master */
if (callback_mask & (1 << I2C_SLAVE_CALLBACK_READ_REQUEST)) {
module->callbacks[I2C_SLAVE_CALLBACK_READ_REQUEST](module);
}
if (module->buffer_length == 0) {
/* Data buffer not set up, NACK address */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
} else {
/* ACK address */
i2c_hw->CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
}
} else {
/* Set transfer direction in dev inst */
module->transfer_direction = I2C_TRANSFER_WRITE;
/* Write request from master */
if (callback_mask & (1 << I2C_SLAVE_CALLBACK_WRITE_REQUEST)) {
module->callbacks[I2C_SLAVE_CALLBACK_WRITE_REQUEST](module);
}
if (module->buffer_length == 0) {
/* Data buffer not set up, NACK address */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
} else {
/* ACK address */
i2c_hw->CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
}
}
/* ACK or NACK address */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x3);
/* ACK next incoming packet */
i2c_hw->CTRLB.reg &= ~SERCOM_I2CS_CTRLB_ACKACT;
} else if (i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_PREC) {
/* Stop condition on bus - current transfer done */
/* Clear Stop interrupt */
i2c_hw->INTFLAG.reg = SERCOM_I2CS_INTFLAG_PREC;
/* Disable interrupts */
i2c_hw->INTENCLR.reg = SERCOM_I2CS_INTFLAG_PREC | SERCOM_I2CS_INTFLAG_DRDY;
if (!((module->enabled_callback & (1 << I2C_SLAVE_CALLBACK_READ_REQUEST))
|| (module->enabled_callback == (1 << I2C_SLAVE_CALLBACK_WRITE_REQUEST)))) {
/* Disable address match if read/write request is not enabled */
i2c_hw->INTENCLR.reg = SERCOM_I2CS_INTFLAG_AMATCH;
}
if (!(module->status == STATUS_ERR_OVERFLOW || module->status == STATUS_ERR_IO)) {
module->status = STATUS_OK;
module->buffer_length = 0;
module->buffer_remaining = 0;
/* Call appropriate callback if enabled and registered */
if ((callback_mask & (1 << I2C_SLAVE_CALLBACK_READ_COMPLETE))
&& (module->transfer_direction == I2C_TRANSFER_WRITE)) {
/* Read from master complete */
module->callbacks[I2C_SLAVE_CALLBACK_READ_COMPLETE](module);
} else if ((callback_mask & (1 << I2C_SLAVE_CALLBACK_WRITE_COMPLETE))
&& (module->transfer_direction == I2C_TRANSFER_READ)) {
/* Write to master complete */
module->callbacks[I2C_SLAVE_CALLBACK_WRITE_COMPLETE](module);
}
}
} else if (i2c_hw->INTFLAG.reg & SERCOM_I2CS_INTFLAG_DRDY) {
/* Check if buffer is full, or NACK from master */
if (module->buffer_remaining <= 0 ||
(module->transfer_direction == I2C_TRANSFER_READ &&
(module->buffer_length > module->buffer_remaining) &&
(i2c_hw->STATUS.reg & SERCOM_I2CS_STATUS_RXNACK))) {
module->buffer_remaining = 0;
module->buffer_length = 0;
if (module->transfer_direction == I2C_TRANSFER_WRITE) {
/* Buffer is full, send NACK */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x2);
/* Set status, new character in DATA register will overflow
* buffer */
module->status = STATUS_ERR_OVERFLOW;
if (callback_mask & (1 << I2C_SLAVE_CALLBACK_ERROR)) {
/* Read complete */
module->callbacks[I2C_SLAVE_CALLBACK_ERROR](module);
}
} else {
/* Release SCL and wait for new start condition */
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_ACKACT;
i2c_hw->CTRLB.reg |= SERCOM_I2CS_CTRLB_CMD(0x2);
/* Transfer successful */
module->status = STATUS_OK;
/* Disable interrupts */
i2c_hw->INTENCLR.reg = SERCOM_I2CS_INTFLAG_DRDY;
}
/* Continue buffer write/read */
} else if (module->buffer_length > 0 && module->buffer_remaining > 0) {
/* Call function based on transfer direction */
if (module->transfer_direction == I2C_TRANSFER_WRITE) {
_i2c_slave_read(module);
} else {
_i2c_slave_write(module);
}
}
}
}
