Fast Ethernet Controller (FEC)
MPC885 PowerQUICC Family Reference Manual, Rev. 2
Freescale Semiconductor
45-21
Table 45-17
describes IVEC fields.
45.3.2.11 RxBD Active Register (R_DES_ACTIVE)
The RxBD active register (R_DES_ACTIVE), shown in
Figure 45-15
, is a command register that should
be written by the user to indicate that the RxBD ring was updated (empty receive buffers have been
produced by the software driver with the E bit set).
Whenever the register is written, the R_DES_ACTIVE bit is set, regardless of the data written by the user.
While the bit is set, the RxBD ring is polled and receive frames (provided ECNTRL[ETHER_EN] is also
set) are processed. Once an RxBD whose E bit is not set is polled, the R_DES_ACTIVE bit is cleared and
polling stops until the user sets the bit again, signifying additional BDs have been placed into the RxBD
ring.
R_DES_ACTIVE is cleared at reset and by clearing ECNTRL[ETHER_EN].
Table 45-17. IVEC Field Descriptions
Bits
Name
Description
0–2
ILEVEL
Interrupt level. The ILEVEL is used to define the interrupt level (0–7) associated with the FEC
interrupt (one of the SIU internal interrupt sources).
3
—
Reserved, should be cleared by the host processor.
4–5
—
Reserved, should be cleared by the host processor.This field may return unpredictable values and
should be masked on a read
6–27
—
Reserved, should be cleared by the host processor.
28–29
IVEC
Interrupt vector, read only. IVEC gives the highest outstanding priority Fast Ethernet interrupt. The
bit field meanings (from low priority to high priority) are as follows:
00 No pending FEC interrupt
01 Non-time-critical interrupt
10 Transmit interrupt
11 Receive interrupt
30–31
—
Reserved, should be cleared by the host processor.
0
6
7
8
15
Field
—
R_DES_ACTIVE
—
Reset
0000_0000_0000_0000
R/W
R/W
Addr
0x0E50 (FEC1) & 0x1E50 (FEC2)
16
31
Field
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Reset
0000_0000_0000_0000
R/W
R/W
Addr
0x0E52 (FEC1) & 0x1E52 (FEC2)
Figure 45-15. R_DES_ACTIVE Register
Summary of Contents for PowerQUICC MPC870
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