Awesome

microcoap

A tiny CoAP server for microcontrollers. See http://tools.ietf.org/html/rfc7252

Endpoint handlers are defined in endpoints.c

• Arduino demo (Mega + Ethernet shield, LED + 220R on pin 6, PUT "0" or "1" to /light)
• POSIX (OS X/Linux) demo
• GET/PUT/POST
• No retries
• Piggybacked ACK only

For linux/OSX

make
./coap

For Arduino

open microcoap.ino

To test, use libcoap

./coap-client -v 100 -m get coap://127.0.0.1/.well-known/core
./coap-client -v 100 -m get coap://127.0.0.1/light
./coap-client -e "1" -m put coap://127.0.0.1/light
./coap-client -e "0" -m put coap://127.0.0.1/light

Or use copper (Firefox plugin)

coap://127.0.0.1

Arduino problem

Arduino, by default, has a UDP transmit buffer of 24 bytes. This is too small for some endpoints and will result in an error.