W5500 Datasheet, PDF (54/65 Pages) List of Unclassifed Manufacturers – Supports 8 independent sockets simultaneously

Sn_TTL (Socket n TTL Register) [R/W] [0x0016] [0x80]
Sn_TTL configures the TTL(Time To Live field in IP header) of Socket n.
It is set before OPEN command.
For more the details, refer to http://www.iana.org/assignments/ip-parameters.
Sn_RXBUF_SIZE (Socket n RX Buffer Size Register) [R/W] [0x001E] [0x02]
Sn_RXBUF_SIZE configures the RX buffer block size of Socket n. Socket n RX Buffer
Block size can be configured with 1,2,4,8, and 16 Kbytes. If a different size is
configured, the data cannot be normally received from a peer.
Although Socket n RX Buffer Block size is initially configured to 2Kbytes, user can
re-configure its size using Sn_RXBUF_SIZE. The total sum of Sn_RXBUF_SIZE cannot be
exceed 16Kbytes. When exceeded, the data reception error is occurred.
When all Sn_RXBUF_SIZE have been configured, Socket n RX Buffer is allocated with
the configured size in 16KB RX Memory and is assigned sequentially from Socket 0 to
Socket 7.
Socket n RX Buffer Block can be accessible with the 16bits Offset Address ranged
from 0x0000 to 0xFFFF regardless of the configured size. (Refer to Sn_RX_RD &
Sn_RX_WR).
Value (dec)
0
1
2
4
8
16
Buffer size
0KB
1KB
2KB
4KB
8KB
16KB
Ex) Socket 0 RX Buffer Size = 8KB
0x001E
0x08
Sn_TXBUF_SIZE (Socket n TX Buffer Size Register) [R/W] [0x001F] [0x02]
Sn_TXBUF_SIZE configures the TX buffer block size of Socket n. Socket n TX
Buffer Block size can be configured with 1,2,4,8, and 16 Kbytes. If a different
size is configured, the data can‟t be normally transmitted to a peer.
Although Socket n TX Buffer Block size is initially configured to 2Kbytes, user
can be re-configure its size using Sn_TXBUF_SIZE. The total sum of
Sn_TXBUF_SIZE cannot be exceed 16Kbytes. When exceeded, the data
transmission error is occurred.
When all Sn_TXBUF_SIZE have been configured, Socket n TX Buffer is allocated
with the configured size in 16KB TX Memory and is assigned sequentially from
Socket 0 to Socket 7.
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W5500 Datasheet Version1.0 (August 2013)