W5300 datasheet(88/128 Pages) WIZNET

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Fig 6. Access to Internal TX Memory

Sn_RX_FIFOR

(SOCKETn

RX FIFO

[R/W]

[0x08230+0x40n/0x230+0x40n]

[0xUUUU]

It indirectly accesses to internal RX memory of SOCKETn.

The internal RX memory can't be directly accessed by the host, but can be accessed through

Sn_RX_FIFOR. If MR(MT) = '0', only the Host-Read of internal RX memory is allowed through

Sn_RX_FIFOR. But if MR(MT) is '1', both of Host-Read and Host-Write are allowed. It should be

set as '0' after verifying the interface between W5300 and the host s

ystem. (Refer to “How to

Test Internal TX/RX memory

”)

If the host system uses 8 bit data bus width, Sn_RX_FIFOR0 and Sn_RX_FIFOR1 should be

accessed in a pair as like Sn_TX_FIFOR. It is not allowed to access Sn_RX_FIFOR0 and

Sn_RX_FIFOR1 right after accessing Sn_TX_FIFOR0 and Sn_TX_FIFOR1. These are cause

for the incorrect read. In order to prevent this, after reading Sn_TX_FIFOR0 and

Sn_TX_FIFOR1, the host reads any register such as Sn_MR and then access Sn_RX_FIFOR.

When the host reads the received DATA packet in internal RX memory through Sn_RX_FIFOR

by 2 bytes, the low and high data in internal RX memory can be read through Sn_RX_FIFOR0

and Sn_RX_FIFOR1 respectively. The host performs RECV command after processing the

received DATA packet in internal RX memory.

According to Sn_MR(P3:P0), PACKET-INFO is added in front of all received DATA packet in

internal RX memory. The added PACKET-INFO contains the packet information such as size.

The host should process PACKET-INFO first and DATA packet later. If the size of received DATA

packet is odd number, 1 byte dummy data is added. The host should read this dummy data first

and ignore it. It is possible to check if the last byte of DATA packet is dummy or not with the size

information of PACKET-INFO.

The host sequentially processes the pairs of PACKET-INFO and DATA packet in internal RX

memory through Sn_RX_FIFOR.

W5300 Datasheet(PDF) 88 Page - WIZnet Co., Ltd