2.1 KiB
CoAP client example
(See the README.md file in the upper level 'examples' directory for more information about examples.) this CoAP client example is adaptation of one of the libcoap example.
CoAP client example would connect your ESP32 device to any CoAP server, fetch data from CoAP server and upstream data to CoAP server.
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
make menuconfig
- Set serial port under Serial Flasher config
- Set Target Uri under Example Configuration
- Set WiFi SSID under Example Configuration
- Set WiFi Password under Example Configuration
Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
make -j4 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
Prerequisite: we startup a CoAP server on coap server example.
and you could receive data from CoAP server if succeed,
such as the following log:
...
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 (2582) event: sta ip: 192.168.3.89, mask: 255.255.255.0, gw: 192.168.3.1
I (2582) CoAP_client: Connected to AP
I (2582) CoAP_client: DNS lookup succeeded. IP=192.168.3.84
Received: Hello World!
E (8102) CoAP_client: select timeout
E (13102) CoAP_client: select timeout
...
Troubleshooting
- Please make sure Target Url includes valid
host,port,path, and begins withcoap://