Interrupts and flags management functions
[CAN_Private_Functions]

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              ##### Interrupts and flags management functions #####
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    [..] This section provides functions allowing to configure the CAN Interrupts 
         and to get the status and clear flags and Interrupts pending bits.
    [..] The CAN provides 14 Interrupts sources and 15 Flags:
   
  *** Flags ***
  =============
    [..] The 15 flags can be divided on 4 groups: 
         (+) Transmit Flags:
             (++) CAN_FLAG_RQCP0. 
             (++) CAN_FLAG_RQCP1. 
             (++) CAN_FLAG_RQCP2: Request completed MailBoxes 0, 1 and 2  Flags
                  Set when the last request (transmit or abort) has 
                  been performed. 
         (+) Receive Flags:
             (++) CAN_FLAG_FMP0.
             (++) CAN_FLAG_FMP1: FIFO 0 and 1 Message Pending Flags; 
                  Set to signal that messages are pending in the receive FIFO.
                  These Flags are cleared only by hardware. 
             (++) CAN_FLAG_FF0.
             (++) CAN_FLAG_FF1: FIFO 0 and 1 Full Flags; 
                  Set when three messages are stored in the selected FIFO.                        
             (++) CAN_FLAG_FOV0.              
             (++) CAN_FLAG_FOV1: FIFO 0 and 1 Overrun Flags; 
                  Set when a new message has been received and passed the filter 
                  while the FIFO was full.         
         (+) Operating Mode Flags: 
             (++) CAN_FLAG_WKU: Wake up Flag; 
                  Set to signal that a SOF bit has been detected while the CAN 
                  hardware was in Sleep mode. 
             (++) CAN_FLAG_SLAK: Sleep acknowledge Flag;
                  Set to signal that the CAN has entered Sleep Mode. 
         (+) Error Flags:  
             (++) CAN_FLAG_EWG: Error Warning Flag;
                  Set when the warning limit has been reached (Receive Error Counter 
                  or Transmit Error Counter greater than 96). 
                  This Flag is cleared only by hardware.
             (++) CAN_FLAG_EPV: Error Passive Flag;
                  Set when the Error Passive limit has been reached (Receive Error 
                  Counter or Transmit Error Counter greater than 127).
                  This Flag is cleared only by hardware.
             (++) CAN_FLAG_BOF: Bus-Off Flag;
                  Set when CAN enters the bus-off state. The bus-off state is 
                  entered on TEC overflow, greater than 255.
                  This Flag is cleared only by hardware.
             (++) CAN_FLAG_LEC: Last error code Flag;
                  Set If a message has been transferred (reception or transmission) 
                  with error, and the error code is hold.                      
  
  *** Interrupts ***
  ==================
    [..] The 14 interrupts can be divided on 4 groups: 
         (+) Transmit interrupt:   
             (++) CAN_IT_TME: Transmit mailbox empty Interrupt;
                  If enabled, this interrupt source is pending when no transmit 
                  request are pending for Tx mailboxes.      
         (+) Receive Interrupts:   
             (++) CAN_IT_FMP0.
             (++) CAN_IT_FMP1: FIFO 0 and FIFO1 message pending Interrupts;
                  If enabled, these interrupt sources are pending when messages 
                  are pending in the receive FIFO.
                  The corresponding interrupt pending bits are cleared only by hardware.
             (++) CAN_IT_FF0.              
             (++) CAN_IT_FF1: FIFO 0 and FIFO1 full Interrupts;
                  If enabled, these interrupt sources are pending when three messages 
                  are stored in the selected FIFO.
             (++) CAN_IT_FOV0.        
             (++) CAN_IT_FOV1: FIFO 0 and FIFO1 overrun Interrupts;        
                  If enabled, these interrupt sources are pending when a new message 
                  has been received and passed the filter while the FIFO was full.
         (+) Operating Mode Interrupts:    
             (++) CAN_IT_WKU: Wake-up Interrupt;
                  If enabled, this interrupt source is pending when a SOF bit has 
                  been detected while the CAN hardware was in Sleep mode.
             (++) CAN_IT_SLK: Sleep acknowledge Interrupt:
                  If enabled, this interrupt source is pending when the CAN has 
                  entered Sleep Mode.       
         (+) Error Interrupts:     
             (++) CAN_IT_EWG: Error warning Interrupt; 
                  If enabled, this interrupt source is pending when the warning limit 
                  has been reached (Receive Error Counter or Transmit Error Counter=96). 
             (++) CAN_IT_EPV: Error passive Interrupt;        
                  If enabled, this interrupt source is pending when the Error Passive 
                  limit has been reached (Receive Error Counter or Transmit Error Counter>127).
             (++) CAN_IT_BOF: Bus-off Interrupt;
                  If enabled, this interrupt source is pending when CAN enters 
                  the bus-off state. The bus-off state is entered on TEC overflow, 
                  greater than 255.
                  This Flag is cleared only by hardware.
             (++) CAN_IT_LEC: Last error code Interrupt;        
                  If enabled, this interrupt source is pending when a message has 
                  been transferred (reception or transmission) with error and the 
                  error code is hold.
             (++) CAN_IT_ERR: Error Interrupt;
                  If enabled, this interrupt source is pending when an error condition 
                  is pending.      
    [..] Managing the CAN controller events: 
         The user should identify which mode will be used in his application to manage 
         the CAN controller events: Polling mode or Interrupt mode.
         (+) In the Polling Mode it is advised to use the following functions:
             (++) CAN_GetFlagStatus() : to check if flags events occur. 
             (++) CAN_ClearFlag()     : to clear the flags events.
         (+) In the Interrupt Mode it is advised to use the following functions:
             (++) CAN_ITConfig()       : to enable or disable the interrupt source.
             (++) CAN_GetITStatus()    : to check if Interrupt occurs.
             (++) CAN_ClearITPendingBit() : to clear the Interrupt pending Bit 
                  (corresponding Flag).
                  This function has no impact on CAN_IT_FMP0 and CAN_IT_FMP1 Interrupts 
                  pending bits since there are cleared only by hardware.