How is ARP Timeout indicated?

Question

I set up an UDP socket. With Wireshark I can see everthing works as expected. even ARP works according the timeout and retry settings. sending a message to a existing node it arrives. processing time only a few milli seconds. adressing a not xisting Node does take even longer. the function call to sendto returns exactly after the timeout/retry period. broadcast messages are also possible, without the need of a ARP interaction. great! BUT, there is not flag indicating the timeout occured. I expected the Sn_IR register will set bit 3 (Sn_IR[3]), but i does not. the find out whether a adressed node is existing can only be done by measuring the time until the function terminated? do anybody know where I find the right flag?

Eugeny · Answer

According to datasheet (see page 39 in RCR explanation section) timeout should be set as you explain. You must enable interrupts using SIMR and Sn_IMR. Do you do it?

Bertram · Answer

Hi Eugeny Thank you. RCR works very well. the timeout is exactly the value I gave the chip byy RTR and RCR. I also played wir the Maskbits including SIR. I understand, if a IR Bit is set due to an event the mask bits enable the interrupt go through. My problem is, that the Flags are never set. even if I am polling the register. Again on the network side every is absolutely fine. only the “CPU side” is the issue.

Bertram · Answer

Well, this is what I did; and as far as I can see, close to your explanation: I am using the wiznet Library. I just renamed socket to wiz_socket as this may collide with Win32 implementation. with the StartTime and EndTime I can measure a possible timeout. Sn_IR always reads 0x00. (code is running on WIn7. and 9HCS12X.) wiz_NetInfo NetInfo = { {0x00,0x00,0xFE,0x77,0x72,0xD8}, //uint8_t mac[6]; ///< Source Mac Address {192,168,0,7}, // uint8_t ip[4]; ///< Source IP Address {255,255,255,0}, // uint8_t sn[4]; ///< Subnet Mask {192,168,0,1}, // uint8_t gw[4]; ///< Gateway IP Address {192,168,0,1}, // uint8_t dns[4]; ///< DNS server IP Address 1 //dhcp_mode dhcp; ///< 1 - Static, 2 - DHCP }; uint8_t addr[4] = { 192,168,0,88 }; wizchip_sw_reset(); wizchip_setnetinfo( &NetInfo ); wiz_socket(0, Sn_MR_UDP, 10000, 0); setSn_IMR(0, 0xFF); printf("
Sn_IMR= %02X", getSn_IMR(0)); //reads : "1F" StartTime = GetTickCount(); wiz_sendto(0,"hello",5,addr,10000); EndTime = GetTickCount(); printf("
Sn_IR= %02X", getSn_IR(0)); //reads : "00" if ((EndTime-StartTime) > 1000) { printf("
	ERROR: target does not respond", EndTime-StartTime); }

Bertram · Answer

You are absolutely right. the bit is read by the function sento. i can see the SOCKERR_TIMEOUT (-13) returned by the function. My fault. you have been of great help, thanks a lot. I owe you something!