MPC5553/MPC5554 Microcontroller Reference Manual, Rev. 5
14-32 Freescale Semiconductor
This register is not reset and must be initialized by the user prior to operation.
14.3.4.3.3 Transmit Buffer Descriptor Ring Start (ETDSR)
The ETDSR is written by the user. It provides a pointer to the start of the circular transmit buffer descriptor
queue in external memory. This pointer must be 32-bit aligned; however, it is recommended it be made
128-bit aligned (evenly divisible by 16). Bits 30 and 31 should be written to 0 by the user. Non-zero values
in these two bit positions are ignored by the hardware.
This register is not reset and must be initialized by the user prior to operation.
0 1 2 3456 7 8 91011121314 15
R R_DES_START
W
Reset U U U U U U U U U U U U U U U U
Address Base + 0x0180
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
R R_DES_START 0 0
W
Reset U U U U U U U U U U U U U U U U
Address Base + 0x0180
1
“U” signifies a bit that is uninitialized.
Figure 14-23. Receive Descriptor Ring Start Register (ERDSR)
Table 14-26. ERDSR Field Descriptions
Bits Name Descriptions
0–29 R_DES_START Pointer to start of receive buffer descriptor queue.
30–31 — Reserved, should be cleared.
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