W7100A-64QFN WIZnet, W7100A-64QFN Datasheet - Page 87

• Manufacturer Part Number: W7100A-64QFN
• Description: 8-bit Microcontrollers - MCU 8051 CORE+HARDWIRED TCP/IP+MAC+PHY
• Manufacturer: WIZnet

Specifications of W7100A-64QFN

• Rohs: yes
• Interface Type: UART

© Copyright 2011 WIZnet Co., Inc. All rights reserved.
peer.
number of retries recorded in RCR, a Timeout Interrupt will occur. (TIMEOUT bit of SOCKET n
Interrupt Register (Sn_IR) is set as ‘1’)
with Sn_IR(TIMEOUT) = ‘1’. Not in TCP communication, only Sn_IR(TIMEOUT) = ‘1’.
and TCP retransmission timeout.
W7100A automatically sends ARP-request to the peer’s IP address in order to acquire MAC
address information (used for communication of IP, UDP, or TCP). As waiting for ARP-response
from the peer, if there is no response during the time set in RTR, timeout occurs and ARP-
request is re-transmitted. It is repeated as many as ‘RCR + 1’ times.
response, the final timeout occurs and Sn_IR(TIMEOUT) becomes ‘1’.
DATA packets) and waits for the acknowledgement (ACK) during the time set in RTR and RCR.
If there is no ACK from the peer, timeout occurs and TCP packets (sent earlier) are
retransmitted. The retransmissions are repeated as many as ‘RCR + 1’ times. Even after TCP
packet retransmissions are repeated ‘RCR +1’ times, if there is no ACK from the peer, final
timeout occurs and Sn_SSR is changed to ‘SOCK_CLOSED” at the same time with
Sn_IR(TIMEOUT) = ‘1’
RCR (Retry Count Register) [R/W] [0xFE0019] [0x08]
This register sets the number of re-transmission. If retransmission occurs more than the
In TCP communication, the value of Sn_SR is changed to ‘SOCK_CLOSED’ at the same time
The timeout of W7100A can be configurable with RTR and RCR. W7100A’s timeout has ARP
At the ARP(Refer to RFC 826, http://www.ietf.org/rfc.html) retransmission timeout,
Even after ARP-request retransmissions are repeated ‘RCR + 1’ times, if there is no ARP-
The value of final timeout (ARP
During the TCP packet retransmission timeout, W7100A transmits TCP packets (SYN, FIN, RST,
The value of final timeout (TCP
Ex) When RTR = 2000(0x07D0), RCR = 8(0x0008),
ARP
N
M
RTR
TO
MAX
= 2000 X 0.1ms X 9 = 1800ms = 1.8s
: Retransmission count, 0 <= N <= M
: RTR X 2
: Minimum value when RTR X 2
TCP
TO
= (
M
N=0
M
Σ
(RTR X 2
ARP
TO
TO
TO
=
) of ARP-request is as below.
) of TCP packet retransmission can be calculated as below,
( RTR X 0.1ms ) X ( RCR + 1 )
N
) + ((RCR-M) X RTR
(M+1)
> 65535 and 0 <= M <= RCR
MAX
) ) X 0.1ms
Ver. 1.12
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