/////////////////////////////////////////////////////////////////////////////
//! Starts a new transfer. If this function is called during an ongoing
//! transfer, we wait until it has been finished and setup the new transfer
//! \param[in] transfer type:<BR>
//! <UL>
//! <LI>IIC_Read: a common Read transfer
//! <LI>IIC_Write: a common Write transfer
//! <LI>IIC_Read_AbortIfFirstByteIs0: used to poll MBHP_IIC_MIDI: aborts transfer
//! if the first received byte is 0
//! <LI>IIC_Write_WithoutStop: don't send stop condition after transfer to allow
//! a restart condition (e.g. used to access EEPROMs)
//! \param[in] iic_port the IIC port (0..MIOS32_IIC_NUM-1)
//! \param[in] address of IIC device (bit 0 always cleared)
//! \param[in] *buffer pointer to transmit/receive buffer
//! \param[in] len number of bytes which should be transmitted/received
//! \return 0 no error
//! \return < 0 on errors, if MIOS32_IIC_ERROR_PREV_OFFSET is added, the previous
//! transfer got an error (the previous task didn't use \ref MIOS32_IIC_TransferWait
//! to poll the transfer state)
//! \note Note that the semaphore will be released automatically after an error
//! (MIOS32_IIC_TransferBegin() has to be called again)
/////////////////////////////////////////////////////////////////////////////
s32 MIOS32_IIC_Transfer(u8 iic_port, mios32_iic_transfer_t transfer, u8 address, u8 *buffer, u16 len)
{
iic_rec_t *iicx = &iic_rec[iic_port];// simplify addressing of record
s32 error;
if( iic_port >= MIOS32_IIC_NUM )
return MIOS32_IIC_ERROR_INVALID_PORT;
// wait until previous transfer finished
if( (error = MIOS32_IIC_TransferWait(iic_port)) ) { // transmission error during previous transfer
iicx->iic_semaphore = 0; // release semaphore for easier programming at user level
return error + MIOS32_IIC_ERROR_PREV_OFFSET;
}
// disable interrupts
MIOS32_IRQ_Disable(); // TODO: disable peripheral
// clear transfer state and error value
iicx->transfer_state.ALL = 0;
iicx->transfer_error = 0;
// set buffer length and start index
iicx->buffer_len = len;
iicx->buffer_ix = 0;
// branch depending on read/write
if( transfer == IIC_Read || transfer == IIC_Read_AbortIfFirstByteIs0 ) {
// take new address/buffer/len
iicx->iic_address = address | 1; // set bit 0 for read operation
iicx->tx_buffer_ptr = NULL; // ensure that previous TX buffer won't be accessed
iicx->rx_buffer_ptr = buffer;
// special option for optimized MBHP_IIC_MIDI
iicx->transfer_state.ABORT_IF_FIRST_BYTE_0 = transfer == IIC_Read_AbortIfFirstByteIs0 ? 1 : 0;
} else if( transfer == IIC_Write || transfer == IIC_Write_WithoutStop ) {
// take new address/buffer/len
iicx->iic_address = address & 0xfe; // clear bit 0 for write operation
iicx->tx_buffer_ptr = buffer;
iicx->rx_buffer_ptr = NULL; // ensure that nothing will be received
// option to skip stop-condition generation after successful write
iicx->transfer_state.WRITE_WITHOUT_STOP = transfer == IIC_Write_WithoutStop ? 1 : 0;
} else {
iicx->iic_semaphore = 0; // release semaphore for easier programming at user level
MIOS32_IRQ_Enable(); // TODO: enable peripheral??
return (iicx->last_transfer_error=MIOS32_IIC_ERROR_UNSUPPORTED_TRANSFER_TYPE);
}
// clear last error status
iicx->last_transfer_error = 0;
// notify that transfer has started
iicx->transfer_state.BUSY = 1;
MIOS32_IRQ_Enable(); // TODO: enable peripheral
// send start condition
iicx->base->I2CONCLR = 0x04; // clear AA (assert acknowledge) bit
iicx->base->I2CONSET = 0x20; // set STA (start) bit
return 0; // no error
}
/////////////////////////////////////////////////////////////////////////////
// Checks the transfer status or waits for status == 0 (no ongoing transfer)
// IN: blocking = 1: waits for the ongoing transfer to finish;
// 0: returns the current transfer status
// OUT: transfer status (1: ongoing; 0: no transfer; < 0: error during last
// transfer. clears the transfer-status on errors.
// (see README for error codes)
/////////////////////////////////////////////////////////////////////////////
s32 FRAM_TransferWaitCheck(u8 blocking){
s32 res;
if(transfer_status == 1){
// ongoing transfer: poll IIC transfer status
transfer_status = blocking ?
MIOS32_IIC_TransferWait(FRAM_IIC_PORT) :
MIOS32_IIC_TransferCheck(FRAM_IIC_PORT);
}
res = transfer_status;
// clear error status
if(transfer_status < 0)
transfer_status = 0;
// return last transfer status
return res;
}
