![NXP Semiconductors LPC43Sxx Скачать руководство пользователя страница 858](http://html1.mh-extra.com/html/nxp-semiconductors/lpc43sxx/lpc43sxx_user-manual_1721827858.webp)
UM10503
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2015. All rights reserved.
User manual
Rev. 2.1 — 10 December 2015
858 of 1441
NXP Semiconductors
UM10503
Chapter 28: LPC43xx/LPC43Sxx Ethernet
28.6.40 DMA Current host receive buffer address register
The Current Host Receive Buffer Address register points to the current Receive Buffer
address being read by the DMA.
28.7 Functional description
28.7.1 Hash filter
To use the hash filter, follow these steps:
1. Calculate CRC32 from the DA (Destination Address) MAC address.
2. Perform a bit-wise reversal of the last two bytes of the value obtained in step 1.
3. Use the first 6 bits of the value obtained in step 2 as follows:
–
The most significant bit determines the hash table register to use.
–
The other 5 bits determine the bit to set in the selected register.
4. In the MAC_FRAME_REGISTER, enable the HMC bit (bit 2) for multicast hash
filtering or the HUC bit (bit 1) for unicast hash filtering.
28.7.1.1 Example for a unicast MAC address
MAC: 5e-45-a2-6c-30-1e
CRC32: 0x94B3F747
Last 2 bytes in binary: 0100 0111
Bit-wise reversal: 1110 0010
First 6 bits: 111000 ( 1=Hash Table High / 11000 => 0x18 => bit 24 )
In the MAC_HASH_TABLE_HIGH register write a 1 to bit 24.
In the MAC_FRAME_FILTER register, set the HUC bit (bit 1) to 1.
Table 643. DMA Current host transmit buffer address register
(DMA_CURHOST_TRANS_BUF, address 0x4001 1050) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
HTB
Host Transmit Buffer Address Pointer
Cleared on Reset. Pointer updated by DMA during
operation.
0
RO
Table 644. DMA Current host receive buffer address register (DMA_CURHOST_REC_BUF,
address 0x4001 1054) bit description
Bit
Symbol
Description
Reset
value
Access
31:0
HRB
Host Receive Buffer Address Pointer
Cleared on Reset. Pointer updated by DMA during
operation.
0
RO