MPC5200B Users Guide, Rev. 1
14-14 Freescale Semiconductor
FEC Registers—MBAR + 0x3000
14.5.3 FEC Interrupt Enable Register—MBAR + 0x3008
The IMASK register provides control over the interrupt events allowed to generate an interrupt. All implemented bits in this CSR are R/W.
This register is cleared by a hardware reset. If corresponding bits in both the IEVENT and IMASK registers are set, the interrupt is signalled
to the CPU. The interrupt signal remains asserted until 1 is written to the IEVENT bit (write 1 to clear) or a 0 is written to the IMASK bit.
14.5.4 FEC Rx Descriptor Active Register—MBAR + 0x3010
The FEC descriptor active register is a command register which should be written by the user to indicate that the receive descriptor ring has
been updated (empty receive buffers have been produced by the driver with the E bit set).
Whenever the register is written the R_DES_ACTIVE bit is set. This is independent of the data actually written by the user. When set, the
FEC will poll the receive descriptor ring and process receive frames (provided ETHER_EN is also set). Once the FEC polls a receive
descriptor whose ownership bit is not set, then the FEC will clear the R_DES_ACTIVE bit and cease receive descriptor ring polling until the
user sets the bit again, signifying additional descriptors have been placed into the receive descriptor ring.

Table1 4-11. FEC Interrupt Enable Register

msb 012345678 9 101112131415
R
HBEEN
BREN
BTEN
GRAEN
TFIEN
Reserved
MIIEN
Rsvd
LCEN
CRLEN
XFUNEN
XFERREN
RFERREN
Rsvd
W
RESET:000000000 0 0 000 0 0
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 lsb
RReserved
W
RESET:000000000 0 0 000 0 0
Bits Name Description
0 HBEEN Heartbeat Error Interrupt Enable
1 BREN Babbling Receiver Interrupt Enable
2 BTEN Babbling Transmitter Interrupt Enable
3 GRAEN Graceful Stop Interrupt Enable
4 TFIEN Transmit Frame Interrupt Enable
5—Reserved
6—Reserved
7—Reserved
8 MIIEN MII Interrupt Enable
9—Reserved
10 LCEN Late Collision Enable
11 CRLEN Late Collision Enable
12 XFUNEN Transmit FIFO Underrun Enable
13 XFERREN Transmit FIFO Error Enable
14 RFERREN Receive FIFO Error Enable
15:31 — Reserved