W5500 serial to HTTP bridge

Question

Hello everyone, I am using a W5500 interfaced via SPI with an STM32F411 to perform transfers of bytes (less than 256) received from one of the serial ports of the STM32 and transmitted with HTTP protocol to a server that receives and record them on a db. Basically, the STM32 receives via serial from another micro a buffer of bytes that maintains and transmits them when possible. I would like to diagnose the status of the HTTP connection before the http request, e.g. during the period when I have nothing to transmit check at set time intervals whether the server is still reachable or not and notify that in advance. I had thought about an ICMP ping but when i try to open the socket it always fail: switch(getSn_SR(s)) { case SOCK_CLOSED: close(s); IINCHIP_WRITE(Sn_PROTO(s), IPPROTO_ICMP); // set ICMP Protocol if(socket(s,Sn_MR_IPRAW,3000,0)!=0){ // open the SOCKET with IPRAW mode, if fail then Error printf( "
 socket %d fail r
", (0)) ; I had also thought about using a TCP Keep-Alive function, but I don’t know if that is a good idea. Does anyone have any suggestions ? I hope to have supplied enought informations Best regards

Eugeny · Answer

It depends on what level you need to check. If you want to check at TCP/IP or other network level, then you do keep-alive and other standard stack functions (check if they are available in the chip you have chosen). However if you want to test HTTP (or any other port application listens to) then you need to do it at the application level - open port to HTTP server and perform small communication or keep port open and sometimes make a short control data exchange. What you say may be something already implemented in e.g. MQTT - check its spec. You can describe your own simple proto, for example having starting byte of 0 for just this byte ping exchange and having byte of 1 as a marker of normal data.

Eugeny · Answer

Regularly request some test page from the web server to see if it is available. Working ping does not mean web server is up and running and is available.

fabry · Answer

It makes sense as a choice I will also evaluate MQTT as a feasibility Thank you