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OVMS3-idf/examples/protocols/coap_server
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Mahavir Jain 7dbf01afad coap: move mbedTLS config options from component to examples 
CoAP component relies on some mbedTLS crypto configuration
options, e.g. DTLS and PSK. These configuration options if
selected, have footprint impact on generic TLS examples like
https_request or https_ota as well.

Footprint of https_request example with/without change is per below:

$ ./tools/idf_size.py new_https_request.map --diff old_https_request.map

<CURRENT> MAP file: new_https_request.map
<REFERENCE> MAP file: old_https_request.map
Difference is counted as <CURRENT> - <REFERENCE>, i.e. a positive number means that <CURRENT> is larger.
Total sizes of <CURRENT>:                                                 <REFERENCE>     Difference
 DRAM .data size:   14796 bytes                                                 14796
 DRAM .bss  size:   23560 bytes                                                 23680           -120
Used static DRAM:   38356 bytes ( 142380 available, 21.2% used)                 38476           -120 (   +120 available,      +0 total)
Used static IRAM:   89045 bytes (  42027 available, 67.9% used)                 89045                (     +0 available,      +0 total)
      Flash code:  554231 bytes                                                563823          -9592
    Flash rodata:  179000 bytes                                                181224          -2224
Total image size:~ 860632 bytes (.bin may be padded larger)                    872568         -11936

This commit moves relevant config options to CoAP specific examples
and also adds some run time warnings if they are kept disabled.

Closes https://github.com/espressif/esp-idf/issues/5262
2020-05-19 17:23:29 +05:30
..
main esp_netif, examples: esp_netif_init() moved into ESP_ERROR_CHECK() 2019-12-17 09:07:49 +01:00
CMakeLists.txt examples/protocols/coap: use common network component 2019-04-15 03:32:05 +00:00
Makefile examples/protocols/coap: use common network component 2019-04-15 03:32:05 +00:00
README.md coap: refactor examples, stylistic cleanups, move certs to independent dir 2019-08-06 10:37:41 +05:30
sdkconfig.defaults coap: move mbedTLS config options from component to examples 2020-05-19 17:23:29 +05:30

README.md

CoAP server example

(See the README.md file in the upper level 'examples' directory for more information about examples.)
This CoAP server example is very simplified adaptation of one of the libcoap examples.

CoAP server example will startup a daemon task, receive requests / data from CoAP client and transmit data to CoAP client.

If the incoming request requests the use of DTLS (connecting to port 5684), then the CoAP server will try to establish a DTLS session using the previously defined Pre-Shared Key (PSK) - which must be the same as the one that the CoAP client is using, or Public Key Infrastructure (PKI) where the PKI information must match as requested.

NOTE: Client sessions trying to use coaps+tcp:// are not currently supported, even though both libcoap and MbedTLS support it.

The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and constrained networks in the Internet of Things.
The protocol is designed for machine-to-machine (M2M) applications such as smart energy and building automation.

Please refer to RFC7252 for more details.

How to use example

Configure the project

idf.py menuconfig

Example Connection Configuration --->

  • Set WiFi SSID under Example Configuration
  • Set WiFi Password under Example Configuration Example CoAP Client Configuration --->
  • If PSK, Set CoAP Preshared Key to use in connection to the server Component config ---> CoAP Configuration --->
    • Set encryption method definition, PSK (default) or PKI
    • Enable CoAP debugging if required

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py build
idf.py -p PORT flash monitor

(To exit the serial monitor, type Ctrl-].)

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

Example Output

current CoAP server would startup a daemon task,
and the log is such as the following:

...
I (332) wifi: mode : sta (30:ae:a4:04:1b:7c)
I (1672) wifi: n:11 0, o:1 0, ap:255 255, sta:11 0, prof:1
I (1672) wifi: state: init -> auth (b0)
I (1682) wifi: state: auth -> assoc (0)
I (1692) wifi: state: assoc -> run (10)
I (1692) wifi: connected with huawei_cw, channel 11
I (1692) wifi: pm start, type: 1

I (2622) event: sta ip: 192.168.3.84, mask: 255.255.255.0, gw: 192.168.3.1
I (2622) CoAP_server: Connected to AP
...

If a CoAP client queries the /Espressif resource, CoAP server will return "Hello World!"
until a CoAP client does a PUT with different data.

libcoap Documentation

This can be found at https://libcoap.net/doc/reference/4.2.0/

Troubleshooting

  • Please make sure CoAP client fetchs or puts data under path: /Espressif or fetches /.well-known/core

  • CoAP logging can be enabled by running 'idf.py menuconfig -> Component config -> CoAP Configuration' and setting appropriate log level