Hi,
My name is Mohamed, I am an embedded systems engineer with over 5years of experience in the field.
By reading your offer I think I am the developer you are looking for. In fact, I already worked on very similar project where I have to write a c library for sending AT commands and http request through a Telit HE910 modem:
https://www.freelancer.com/projects/C-Programming/Need-convert-file-run-project/
I am positive I will help you complete your project fast with a quality code and easy communication.
I suggest you a chat to help us discuss your need in details