I have tried freelancer 6 months ago for this same project. One fellow who had worked in industrial control probably could have done this easily. I lost his coordinates.
I want to be able to buy an Android phone wherever in the world. With this, I need to be able to install the app I need you to design from the cloud. I must also be able to download the hex file which corresponds to to the firmware version of the propriatary equipment I need to upgrade. These are embedded microcontroller circuits.
The app needs to install the firmware in the microcontroller through the USB OTG port of the Android phone.
I have the entire program in modular C to coordinate all programming activities. All U need to add is file handling Web download and I/O porting through the host USB.