Dear Sir/Madam,
I have 10 years of experience in embedded systems with good knowledge of hardware and low level software and currently working in a startup, so I know the naunces of prototype projects and have done end to end solutions with single point contact. Though I could not get the complete requirement for your project I understand you need hardware design for some product prototype using the arduino and manage that particular hardware through the code running in arduino. May be you want to control some peripheral like GPS, led, motor, wifi chip, sim module etc which will be connected through IO pins or I2C or uart. I have the experience in handling all of them and more and have worked on Arduino too. Through Freelancer this is my first project, but don't fret as I have done quite a few freelancing outside.
Regards,
Ajith