Freescale Semiconductor MPC5200B - Manual (Page 678)

Functional Description
MPC5200B Users Guide, Rev. 1
Freescale Semiconductor 19-39
19.7.9.4 Error Interrupt
An overrun of the receiver FIFO, error, warning or Bus-Off condition occurred. The Section 19.5.7, MSCAN Receiver Flag Register
(CANRFLG)—MBAR+0x0908 / 0x988 indicates one of the following conditions:
• Overrun
An overrun condition of the receiver FIFO as described in Section 19.7.2.3, Receive Structures occurred.
• CAN Status Change
The actual value of the Transmit and Receive Error Counters control the bus state of the MSCAN.
As soon as the error counters skip into a critical range (Tx/Rx-Warning, Tx/Rx-Error, Bus-Off) the MSCAN flags an error condition.
The status change, which caused the error condition, is indicated by the TSTAT and RSTAT flags (see section
Section 19.5.7,
MSCAN Receiver Flag Register (CANRFLG)—MBAR+0x0908 / 0x988 and Section 19.5.8, MSCAN Receiver Interrupt Enable
Register (CANRIER)—MBAR + 0x0909 / 0x989 ).
19.7.10 Interrupt Acknowledge
Interrupts are directly associated with one or more status flags in either the Section 19.5.7, MSCAN Receiver Flag Register
(CANRFLG)—MBAR+0x0908 / 0x988 or the Section 19.5.9, MSCAN Transmitter Flag Register (CANTFLG)—MBAR + 0x090C / 0x98C .
Interrupts are pending as long as one of the corresponding flags is set. The flags in the above registers must be reset within the interrupt handler
to handshake the interrupt. The flags are reset by writing a “1” to the corresponding bit position. A flag cannot be cleared if the respective
condition still prevails.
NOTE
It must be guaranteed that the CPU only clears the bit causing the current interrupt. For this reason,
bit manipulation instructions (BSET) must not be used to clear interrupt flags. These instructions may
cause accidental clearing of interrupt flags which are set after entering the current interrupt service
routine.
19.7.11 Recovery from STOP or WAIT
The MSCAN can recover from Sleep Mode via the Wake-Up interrupt. This interrupt can only occur if the MSCAN is in Sleep Mode
(SLPRQ=1 and SLPAK=1), the wake-up option is enabled (WUPE=1) and the Wake-Up interrupt is enabled (WUPIE=1).