[From QnA]WIZ811MJ not sending back an ACK packet


#1

Dear Representative,

I am having an issue. Usually when the single board computer send the WIZ811MJ a short message through TCPIP, everything works okay. However when it send me a longer message around 800 byte, the transmission fails and the single board computer would keep on retransmit the TCPIP message.

Is this due to the WIZ811MJ not sending back an ACK packet fast enough? Under normal operation, does the WIZ811MJ send an ACK packet automatically? When does it send the ACK, under what condition? Does it wait for my MCU to send a special command?

I read in the datasheet page 25 of wiznet.co.kr/UpLoad_Files/Re … v1.2.4.pdf

What is this exactly? What is the internal Timeout mechanism?

Thanks!


#2

Dear customer,
Thanks for your interest in wiz811mj and w5100.

Could you please confirm which tx_mem_size and rx_mem_size is correct?

Is this due to the WIZ881MJ not sending back an ACK packet fast enough?
-> If ND/MC is set as ‘1’, ACK packet is transmitted whenever receiving data packet from the peer.

Under normal operation, does the WIZ811MJ send an ACK packet automatically?
->ACK packet is transmitted according to internal Timeout mechanism.

What is the internal Timeout mechanism?
->RTR(Retry Time-value Register) sets the period of timeout.
Value 1 means 100us. The initial value is 2000(0x07D0). That will be set as 200ms.
Ex) For 400ms configuration, set as 4000(0x0FA0)

0x0017 0x0018
0x0F 0xA0

Reference point.
RCR sets the number of re-transmission. If retransmission occurs more than the number recorded in RCR, Timeout Interrupt (TIMEOUT bit of Socket n Interrupt Register(Sn_IR) is set as ‘1’) will occur.

Thank,
WIZnet