Hello,
My name is Andrei, i am a Romanian IOT Developer with a lot of experience in IOT projects and automatics .
I have read the requirements and looks nice , i can do it for you with some additional questions, but for the start i need the model of the mp3 shield .
I can work with all types of Microcontroles programming in C , C++ , Mikro C , CCS C , Atmel Studio , Arduino , gcc .
Creating Schematics and PCB in Kicad , Eagle , EasyEDA and Proteus (+simulation).
I have an workshop full of parts and the infrastructure to build PCB and test the solution end to end using special tools (Spectrum analyzers , oscilloscope , logic analyzers )
Derivable on the project :
wiring diagram for prof of concept
Schematic design
MCU code explained
As an additional service i can make you a full working prototype and ship to you.
Regards,
Andrei