I like to send a simple CoAP message to a CoAP server, but the BC95-G module apparently does not transmit the payload part of the CoAP message.
To test, I set up a simple UDP server that does nothing but let the client (the BC95-G) module connect via UDP and puts out the bytes received.
Some version info
AT+CGMR
SSB,V150R100C10B200SP1
SECURITY_A,V150R100C20B300SP2
PROTOCOL_A,V150R100C20B300SP2
APPLICATION_A,V150R100C20B300SP2
SECURITY_B,V150R100C20B300SP2
RADIO,Hi2115_RF0
OK
I let the module auto-connect to the network, there is no issue with that. Everything is okay, module is connected in “roaming” mode.
AT+CEREG?
+CEREG:0,5
OK
AT+QCOAPCREATE=56830
OK
AT+QCOAPHEAD=3,0
OK
AT+QCOAPOPTION=1,11,"events"
OK
AT+QCOAPSEND=0,2,95.208.xx.yy,20001
>
After the “>” prompt, I entered 0102 followed by CTRL-Z key.
I get
OK
So for me everything seems to be alright, up to the fact that on the server side I receive the following:
40020000b66576656e7473
There is a nice page how to interpret these bytes at https://developers.wia.io/release/apis/coap-packet-structure
This shows a POST request (Code: 02) with message id 0000 being submitted to the uri-path “events” (b66576656e7473
). BUT THE PAYLOAD IS MISSING
I would expect the following:
40020000b66576656e7473ff0102
with ff
being the “payload marker” and 0102
being the payload.
The question is, why isn’t the payload added to the CoAP message although obviously all steps, including entering the payload after the prompt was successful.