Datasheet

W5500 Datasheet Version1.0.9 39 / 66
the TCP packet is retransmitted. The retransmission is repeated as many as ‘RCR+1’.
Even after TCP retransmission is repeated as ‘RCR+1’ and there is no response to the
TCP retransmission, the final timeout is occurred and Sn_IR(TIMEOUT) becomes ‘1’.
The time of final timeout (TCPTO) of TCP retransmission is as below.
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N : Retransmission count, 0≤N ≤ M
M : Minimum value when RTR x 2
(M+1)
> 65535 and 0 ≤ M ≤ RCR
RTRMAX : RTR x 2
M
Ex) When RTR = 2000(0x07D0), RCR = 8(0x0008),
ARP
TO
= 2000 X 0.1ms X 9 = 1800ms = 1.8s
TCP
TO
= (0x07D0+0x0FA0+0x1F40+0x3E80+0x7D00+0xFA00+0xFA00+0xFA00+0xFA00) X 0.1ms
= (2000 + 4000 + 8000 + 16000 + 32000 + ((8 - 4) X 64000)) X 0.1ms
= 318000 X 0.1ms = 31.8s
PTIMER (PPP Link Control Protocol Request Timer Register) [R/W] [0x001C] [0x0028]
PTIMER configures the time for sending LCP echo request. The unit of time is 25ms.
Ex) in case that PTIMER is 200,
200 * 25(ms) = 5000(ms) = 5 seconds
PMAGIC (PPP Link Control Protocol Magic number Register) [R/W] [0x001D] [0x00]
PMAGIC configures the 4bytes magic number to be used in LCP echo request.
Ex) PMAGIC = 0x01
0x001D
0x01
LCP Magic number = 0x01010101