HTTP request over SIM900 to Thingspeak is not working when the code is uploaded to Arduino

Thread Starter

Miloš Mladenović

Joined Aug 8, 2019
I am trying to send the sensor data to the Thingspeak cloud over GSM module SIM900 attached to Arduino.
The main goal of the project is to send the ECG data in the real time and display it on the remote computer using Python, in which some additional analysis should be done using the data from the cloud.
When entering AT commands to the serial monitor one by one and sending a simple constant (not sensor data), that constant is displayed properly on the graph. After putting all those commands into Arduino sketch, the code has unpredictable behaviour and the data is simply not sent to the server.
I tried many different approaches but nothing seems to work so far.
The code is in the attachment.