I am succeeding in sending an update string via a SIM800L to ThingSpeak but the channel is not updating the channel. I know the string is correct since it is provided by the site that I am posting to.

I have read on this site that the string length needs to be defined to be 4 more than the character count. Does this always work?

Where would one find instructions regarding correct use the AT-CIPSEND command with SIM Tech devices?

I using an Arduino Pro Mini and interfacing with the modem using a Software Serial connection.

  • \$\begingroup\$ Need more clarifications and explanations on what is your whole setup \$\endgroup\$
    – Mitu Raj
    Mar 26, 2018 at 15:50
  • \$\begingroup\$ The secret is that the request string needs to be terminated with a double carriage return and line feed. \$\endgroup\$ Mar 30, 2018 at 10:15

1 Answer 1


The string needs to be terminated with a carriage return and newline and then followed by a further carriage return and newline. I now use println("GET /update?...." ) for the request string and follow it with a final println().


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