
Fast Ethernet Controller (FEC)
19-24
Freescale Semiconductor
19.4.24 Receive Buffer Size Register (EMRBR)
The EMRBR is a user-programmable register that dictates the maximum size of all receive buffers. This
value should take into consideration that the receive CRC is always written into the last receive buffer. To
allow one maximum size frame per buffer, EMRBR must be set to RCR[MAX_FL] or larger. To properly
align the buffer, EMRBR must be evenly divisible by 16. To ensure this, bits 3–0 are forced low.
To minimize bus utilization (descriptor fetches), it is recommended that EMRBR be greater than or equal
to 256 bytes.
The EMRBR register is undefined at reset and must be initialized by the user.
Address: 0xFC03_0184
Access: User read/write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R
X_DES_START
0
0
W
Reset — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —
Figure 19-23. Transmit Buffer Descriptor Ring Start Register (ETDSR)
Table 19-27. ETDSR Field Descriptions
Field
Description
31–2
X_DES_START
Pointer to start of transmit buffer descriptor queue.
1–0
Reserved, must be cleared.
Address: 0xFC03_0188
Access: User read/write
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
R 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
R_BUF_SIZE
0 0
0
0
W
Reset — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —
Figure 19-24. Receive Buffer Size Register (EMRBR)
Table 19-28. EMRBR Field Descriptions
Field
Description
31–11
Reserved, must be cleared.
10–4
R_BUF_SIZE
Maximum size of receive buffer size in bytes. To minimize bus utilization (descriptor fetches), set this field to 256
bytes (0x10) or larger.
0x10 256 + 15 bytes (minimum size recommended)
0x11 272 + 15 bytes
...
0x7F 2032 + 15 bytes. The FEC writes up to 2047 bytes in the receive buffer. If data larger than 2047 is
received, the FEC truncates it and shows 0x7FF in the receive descriptor
3–0
Reserved, must be cleared.
MCF5329 Reference Manual, Rev 3
Summary of Contents for MCF5329
Page 106: ...ColdFire Core 3 32 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 148: ...Cache 5 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 154: ...Static RAM SRAM 6 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 184: ...Power Management 8 18 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 204: ...Reset Controller Module 10 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 220: ...System Control Module SCM 11 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 228: ...Crossbar Switch XBS 12 8 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 268: ...General Purpose I O Module 13 40 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 392: ...SDRAM Controller SDRAMC 18 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 436: ...Fast Ethernet Controller FEC 19 44 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 594: ...FlexCAN 23 30 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 678: ...Pulse Width Modulation PWM Module 26 22 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 684: ...Watchdog Timer Module 27 6 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 704: ...DMA Timers DTIM0 DTIM3 29 12 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 754: ...UART Modules 31 34 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 770: ...I2 C Interface 32 16 Freescale Semiconductor MCF5329 Reference Manual Rev 3...
Page 866: ...Debug Module 36 50 Freescale Semiconductor MCF5329 Reference Manual Rev 3...