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Fast Ethernet Controller (FEC)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
25-25
25.3.4.18 Descriptor Group Lower Address (GALR)
The GALR register is written by the user. This register contains the lower 32 bits of the 64-bit hash table
used in the address recognition process for receive frames with a multicast address. This register must be
initialized by the user.
25.3.4.19 FIFO Transmit FIFO Watermark Register (TFWR)
The TFWR is a 32-bit read/write register with one 2-bit field programmed by the user to control the
amount of data required in the transmit FIFO before transmission of a frame can begin. This allows the
user to minimize transmit latency (TFWR = 0x) or allow for larger bus access latency (TFWR = 11) due
to contention for the system bus. Setting the watermark to a high value minimizes the risk of transmit FIFO
underrun due to contention for the system bus. The byte counts associated with the TFWR field may need
to be modified to match a given system requirement (worst case bus access latency by the transmit data
DMA channel).
Table 25-20. GAUR Field Descriptions
Field
Description
GADDR1
The GADDR1 register contains the upper 32 bits of the 64-bit hash table used in the address recognition
process for receive frames with a multicast address. Bit 31 of GADDR1 contains hash index bit 63. Bit 0 of
GADDR1 contains hash index bit 32.
Offset: FE 0x0124
Access: User read/write
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
R
GADDR2
W
Reset
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
R
GADDR2
W
Reset
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
U
Figure 25-19. Descriptor Group Lower Address Register (GALR)
Table 25-21. GALR Field Descriptions
Field
Description
GADDR2
The GADDR2 register contains the lower 32 bits of the 64-bit hash table used in the address recognition
process for receive frames with a multicast address. Bit 31 of GADDR2 contains hash index bit 31. Bit 0 of
GADDR2 contains hash index bit 0.
Summary of Contents for PXN2020
Page 1: ...PXN20 Microcontroller Reference Manual Devices Supported PXN2020 PXN2120 PXN20RM Rev 1 06 2011...
Page 42: ...PXN20 Microcontroller Reference Manual Rev 1 lxiv Freescale Semiconductor...
Page 64: ...Introduction PXN20 Microcontroller Reference Manual Rev 1 1 22 Freescale Semiconductor...
Page 112: ...Signal Description PXN20 Microcontroller Reference Manual Rev 1 3 44 Freescale Semiconductor...
Page 118: ...Resets PXN20 Microcontroller Reference Manual Rev 1 4 6 Freescale Semiconductor...
Page 372: ...e200z6 Core Z6 PXN20 Microcontroller Reference Manual Rev 1 13 8 Freescale Semiconductor...
Page 412: ...e200z0 Core Z0 PXN20 Microcontroller Reference Manual Rev 1 14 14 Freescale Semiconductor...
Page 821: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 Freescale Semiconductor 27 49...
Page 822: ...Media Local Bus MLB PXN20 Microcontroller Reference Manual Rev 1 27 50 Freescale Semiconductor...
Page 1376: ...Memory Map PXN20 Microcontroller Reference Manual Rev 1 A 118 Freescale Semiconductor...