ESP8266 Community Forum

- Wed Nov 25, 2015 5:10 pm #35003 Hello everyone,

we just released our free CoAP stack ("lobaro-coap") to the esp8266 platform.
Our CoAP implementation was primary designed for embedded hardware platforms and easy usage.

Features are:

* easy to use “C” CoAP stack
* open source (MIT)
* complete request/response logic
* complete retry logic
* piggybacked & separate reponses
* prepared for sleeping server
* runs on static memory are with own memory allocator
* no need for FreeRTOS SDK (but should be no problem)
* only one UDP socket internally used
* wifi credentials can be set via CoAP on esp8266 softAP interface

Give it a try at (also with ready to test binaries):
http://www.lobaro.com/lobaro-coap-on-esp8266/
and
http://www.lobaro.com/lobaro-coap/

Any comments and feedback are highly appreciated!

Tobi

Lobaro IoT - Industrial IoT Solutions - www.lobaro.com

- Tue Feb 02, 2016 9:30 am #40267 Hi Tobi,

I have been using your library for the last couple of days and I have successfully managed to create a bunch of resources to handle all of the server slide elements for my project, however I have been having some difficulty creating a simple client side implementation, so I was hoping that you could point me to a simple example or perhaps provide some advice on how to best solve the issue.

So far I have used the 'CoAP_CreateMessage', 'CoAP_StartNewClientInteraction' and 'CoAP_SendMsg' methods however I don't appear to be receiving any messages on the server side, but given a simple example I am sure I could work it out.

I have looked though your website (cool products btw), but as far as I can tell there are only examples for server side implementations. Any assistance would be much appreciated, and thank you very much for all your hard work in creating the library.

- Tue Feb 02, 2016 4:10 pm #40303 Hi!
Thanks for your feedback!

Have you tried the function "CoAP_StartNewGetRequest(...)"? It's a easy wrapper for the most common used functionality of "COAP GET" using the CoAP_StartNewClientInteraction function just internally.

Code: Select allCoAP_Result_t _rom CoAP_StartNewGetRequest(char* UriString, uint8_t ifID, NetEp_t* ServerEp, CoAP_RespHandler_fn_t cb) {

   CoAP_Message_t* pReqMsg = CoAP_CreateMessage(CON, REQ_GET, CoAP_GetNextMid(),NULL, 0,0, CoAP_GenerateToken());

   if(pReqMsg != NULL) {
      CoAP_AppendUriOptionsFromString(&(pReqMsg->pOptionsList), UriString);
      return CoAP_StartNewClientInteraction(pReqMsg, ifID, ServerEp, cb);
   }

   INFO("- New GetRequest failed: Out of Memory\r\n");

   return COAP_ERR_OUT_OF_MEMORY;
}

It should be used with an callback like this:

Code: Select allCoAP_Result_t sendRequestCB(CoAP_Message_t* pRespMsg, NetEp_t* Sender) {
   INFO("Callback to request received!\r\n");
   return COAP_OK;
}

void sendRequest() {
   //send to remote CoAP server at //fe80:0000:0000:0000:0211:7d00:0030:8e3f with Port 5683
   NetEp_t receiver = {.NetType = IPV6, .NetPort = 5683, .NetAddr.IPv6.u8 = IPv6_IP(0xfe800000, 0x00000000, 0x02117d00, 0x00308e3f)};
   //NetEp_t receiver = {.NetType = IPV4, .NetPort = 5683, .NetAddr.IPv4.u8 = {192,168,4,4}};
   CoAP_StartNewGetRequest("/battery-vcc", 0, &receiver,  sendRequestCB);
}

Please tell me if this helps

Lobaro IoT - Industrial IoT Solutions - www.lobaro.com

- Tue Feb 02, 2016 5:51 pm #40310 Thanks for getting back so quickly, to be honest I hadn't tried that since I was looking for a PUT example so I kinda glazed over that, but thanks to your help I have now got that implemented and have the ESP sending GET requests to the server.
I think part of the reason I couldn't work it out was I didn't know that callbacks were available in C. I have only used them in Javascript, so I was rather confused by why there was method names but without the brackets, but that makes sense now.