sending Json data to server using AT commands

Question

I am having a website which accepts json data with post method.It works fine when i try sending the request from POSTMAN rest client. When i am trying to the same using AT commands its failing.

This is the AT sequence i tried

AT
AT+CREG? 
AT+CGATT?
AT+CIPSHUT
AT+CIPSTATUS
AT+CIPMUX=0 
AT+CGDCONT=1,"IP","airtelgprs.com"
AT+CSTT="airtelgprs.com"
AT+CIICR
AT+CIFSR
AT+CIPSTATUS
AT+CIPSTART= "TCP","obdsam.herokuapp.com","80"
AT+CIPSEND
>
POST /newtasks HTTP/1.1 (Ctrl+M + Ctrl+J)
HOST: obdsam.herokuapp.com" (Ctrl+M + Ctrl+J)
Accept: application/json (Ctrl+M + Ctrl+J)
Content-Type: application/json (Ctrl+M + Ctrl+J)
{"RPM":"41","ECT":"20"} (Ctrl+M + Ctrl+J)
(ctrl+j)(ctrl+z)

What could be the issue?

This is the reply from serial terminal

score 2 · Accepted Answer · answered Dec 01 '15 at 18:54

2

Solved the issue. After AT+CIPSEND the message must be like this >

POST /newtasks HTTP/1.1 (Ctrl+M + Ctrl+J)
HOST: obdsam.herokuapp.com (Ctrl+M + Ctrl+J)
Accept: application/json (Ctrl+M + Ctrl+J)
Content-Type: application/json(Ctrl+M + Ctrl+J)
Content-Length: 23 (Ctrl+M + Ctrl+J) (Ctrl+M + Ctrl+J)
{"RPM":"55","ECT":"55"} (Ctrl+M + Ctrl+J)(ctrl+j)(ctrl+z)

answered Dec 01 '15 at 18:54

ganeshredcobra

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what is Ctrl+M Ctrl+J etc? Do I need it? – Amir Mar 05 '19 at 11:25
@Amir its CR and LF, you need to send that, see asciitable for combinations. – ganeshredcobra Mar 07 '19 at 16:26

score 1 · Answer 2 · edited Feb 06 '17 at 20:19

I personally have observed common mistakes in omitting (ctrl+m)(ctrl+j) combinations. In the above post , the first five lines belongs to HTTP header and the sixth line is the HTTP body. Note that the fifth line should end with two sets of carriage return and line feed to indicate end of HTTP header.

Also, wait until CIPSTART returns CONNECT OK, and wait until > appears afterCIPSEND`.

If you are GET/POST-ing a page with dynamic IP, your code should be quick enough to fetch/post the page before the IP changes.

Have a nice day....

sending Json data to server using AT commands

2 Answers2