Memory Map/Register Definition
MCF548x Reference Manual, Rev. 3
Freescale Semiconductor 30-39

30.3.3.31 FEC Transmit FIFO Alarm Register (FECTFAR)

This pointer provides low level alarm information to the user and the comm bus interface. A low level

alarm reports lack of data. The alarm register defines the alarm threshold for the number of bytes in the

FIFO. If there are less than or equal FECTFAR[ALARM] bytes of data in the FIFO, the

FECTFSR[ALARM] bit is set.

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R0000000000000000
W
Reset0000000000000000
1514131211109876543210
R000000 LWFP
W
Reset0000000000000000
Reg
Addr
MBAR + 0x91B4 (FEC0), 0x99B4 (FEC1)

Figure 30-33. FEC Transmit FIFO Last Write Frame Pointer Register (FECTLWFP)

Table 30-37. FECTLWFP Field Descriptions

Bits Name Descriptions
31–10 Reserved, should be cleared.
9–0 LWFP Last write frame pointer. This pointer indicates the location of the next byte after the last frame that
has been completely written. If no frames have been read out of the FIFO, LWFP indicates the first
byte location in the FIFO( the reset state).
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
R0000000000000000
W
Reset0000000000000000
1514131211109876543210
R000000 ALARM
W
Reset0000000000000000
Reg
Addr
MBAR + 0x91B8 (FEC0), 0x99B8 (FEC1)

Figure 30-34. FEC Transmit FIFO Alarm Register (FECTFAR)