CoAP Simple GET — Native API

Minimal two-board demo: one node runs a CoAP server with path hello, the other sends a confirmable GET and prints the payload on Serial. The Leader forms the network with a fixed dataset; the client joins using the network key only (no Commissioner).

Sketch	Role
server (Leader + CoAP server)	Thread Leader + CoAP server on port 5683
client (one-shot GET)	Thread Child + one-shot GET client

Parameter	Value
Network name	ESP_OT_CoAP_Demo
Channel	24
PAN ID	0xC0A0
CoAP path	hello

The server registers onHello() in callback mode (no CoAP polling in loop()). The client uses setConfirmable(true) for a reliable GET with response.

How to Run

1. Flash server (Leader + CoAP server) on one ESP32-H2 / ESP32-C6 / ESP32-C5 board and open Serial Monitor at 115200.
2. Wait until Serial shows Attached as Leader and CoAP server listening on path 'hello'.
3. Flash client (one-shot GET) on a second board (same NETKEY as the server).
4. The client performs one GET on hello and prints the response.

Each sketch has its own README with configuration, expected output, and troubleshooting.

Required IDF features (sdkconfig)

Feature	Used by
CONFIG_OPENTHREAD_ENABLED=y	Both sketches
CONFIG_SOC_IEEE802154_SUPPORTED=y	Both sketches

Troubleshooting

Startup order: Flash CoAP SimpleGet — server first and wait for Attached as Leader and CoAP server listening on path 'hello'. Then flash CoAP SimpleGet — client. The client only needs the same NETKEY as the server — reset the client if it booted before the server was Leader, or erase flash after changing dataset constants.

Symptom	Likely cause
Client Thread attach failed	Flash server first and wait for Leader. Client needs the same NETKEY.
Client Started as Leader	Server not running — client formed its own network. Start server, erase client flash, retry.
Client started before server	No Leader on the mesh — start server, then reset client.
GET hello -> error timeout	Separate Thread partitions (wrong startup order) or server CoAP not started.
Wrong payload or attach to wrong network	Stale NVS dataset on either board — erase flash on both boards.

See Also

• CoAP Light Switch — multicast lamp control over CoAP.
• Native CoAP examples overview — all Native CoAP demos and port conventions.
• CLI CoAP examples — CLI-based CoAP demos for comparison.

License

Apache License 2.0.