MC9S12NE64_06 Datasheet, PDF (326/554 Pages) Freescale Semiconductor, Inc – Microcontrollers

Chapter 11 Ethernet Media Access Controller (EMACV1)
11.3.2.15 Ethernet Buffer Configuration (BUFCFG)
Module Base + $18
15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
R
0
W
BUFMAP
0
MAXFL
RESET: 0
1
0
0
0
1
0
1
1
1
1
0
1
1
1
0
= Unimplemented or Reserved
Figure 11-16. Ethernet Buffer Configuration (BUFCFG)
Read: Anytime.
Write: See each field description.
BUFMAP — Buffer Size and Starting Address Mapping
This 3-bit field can be written once after a hardware or software reset and only while EMACE is clear.
Any write to this field while EMACE is set is ignored.
This field specifies the buffer size and the base address within system RAM for the receive and
transmit Ethernet buffers. Table 11-7 shows the mapping configuration for the system RAM. The
starting address of the system RAM depends on its position within the on-chip system memory map.
Table 11-7. Buffer Mapping Configuration on System RAM
BUFMAP
0
1
2
3
4
5–7
System
RAM
Starting
Address
0x0000
0x0000
0x0000
0x0000
0x0000
RX Buffer A
Size
(Bytes)
RX Buffer A
Address
Space
RX Buffer
B size
(Bytes)
RX Buffer B
Address
Space
TX Buffer Start
Address
128
256
512
1K
1.5K
0x0000 - 0x007F 128
0x0000 - 0x00FF 256
0x0000 - 0x01FF 512
0x0000 - 0x03FF 1K
0x0000 - 0x05FF 1.5K
Reserved
0x0080 - 0x00FF
0x0100 - 0x01FF
0x0200 - 0x03FF
0x0400 - 0x07FF
0x0600 - 0x0BFF
0x0100
0x0200
0x0400
0x0800
0x0C00
MAXFL — Receive Maximum Frame Length
This 11-bit field can be written anytime, but the user must not change this field while EMACE is set.
The 11-bit field specifies the maximum receive frame length in bytes. Receive frames exceeding
MAXFL causes the BREIF event bit to set and an interrupt occurs if the BREIE is also set. Written
values equal-to or less-than 0x040 (64 decimal) use the minimum of 0x040. Written values equal-to
or greater-than 0x5EE (1518 decimal) use the maximum of 0x5EE.
MC9S12NE64 Data Sheet, Rev. 1.1
326
Freescale Semiconductor