w5500 timeout

Question

Hi! there is a code that checks a time out in function sendto() and when it can’t reach some node it trys to resend (inside the chip) and gives a delay which can be configured like this: gWIZNETtimeout.retry_cnt=xxx; gWIZNETtimeout.time_100us=xxx; ctlnetwork(CN_SET_TIMEOUT, (void*)&gWIZNETtimeout); so my questions are Does the chip issues an ARP request (but I don’t see it on wire shark)or something else on every sentto() which checks the remote node online? default delay is set to 0.2 sec x 8 -and it gives a 1.6 sec delay. before SOCKERR_TIMEOUT… can I use 2ms and 2 trys (it works but not shure what affects to)? Or how to avoid this big delay when sending to offline node? sendto() -delay fragment { … while(1) { tmp = getSn_IR(sn); if(tmp & Sn_IR_SENDOK) { setSn_IR(sn, Sn_IR_SENDOK); break; } //M:20131104 //else if(tmp & Sn_IR_TIMEOUT) return SOCKERR_TIMEOUT; else if(tmp & Sn_IR_TIMEOUT) { setSn_IR(sn, Sn_IR_TIMEOUT); return SOCKERR_TIMEOUT; } //////////// } return len; }

GYUR22 · Answer

I found only partial answer, but how to get mac address of remote node… SEND_MAC 0x21 Valid only in UDP mode. The basic operation is sa me as SEND. Normally SEND transmits data after destination hardware address is acquired by the automatic ARP -process(Address Resolution Protocol). But SEND_MAC transmits data without the automatic ARP-process. In this case, the destination hardware address is acquired from Sn_DHAR configured by host, instead of APR -process.

GYUR22 · Answer

Thank you, but what do you mean -“But if you set it to 2ms and 8try, it’s not a 1.6s delay”? Is it any way to get incoming mac adress in udp ? Or get acces to arp cache ? Or issue an arp request and get the mac out of it? And when we have unseccesful send to offline node does the arp cache cleare?

GYUR22 · Answer

Thank you for reply! My particular problem - I’m using Steeve Karg BACnet stack (UDP protocol) and until I was trying to implement P2P every thing were ok. But I got a very long function blocking time when sendto() trying to send to offline node -controller is the initiator of message. And I’m sendind to many nodes via one socket. If can get a mac I can avoid arp which block function and send directly. But where I can get incoming mac or create my own arp? In conclusion - I need to send recive to/from different ip’s from one socket by UDP protocol.