Hi,
I am new freelancer here, but I worked in android for 5 years.
This app need following key tech:
1) USB device detection:
Register filter by android.hardware.usb.action.USB_DEVICE_ATTACHED to launch app when an USB device is attached. Of course, we can use vid/pid to filter USB devices who is desire to communicate with. Then can use UsbManager/UsbDevice get the device instance to communicate. In one words, this app only can work in android device which support USB OTG. Am I right? I suppose this app work on a USB OTG android device as a host.
2) data transfer:
Use UsbDeviceConnection to read/write data. Also, this part need you to provide a detail spec to define the data format.
3) graphical GUI to display in realtime:
need custom a view to draw the graphical GUI in realtime. Maybe need to extend from View depending on what effect you want.
4) Log all data:
Write raw data to storage or store data in SQLite database depending on the data format.
5) Email capable:
Suppose to send Email by using some stock email client. And it's easy. if need to build-in a SMTP in our app also is fine. But this need user to register an email account in our app.
This project is my first project, and I want to gain confidence here. Hope to work for you. I can provide a demo in two days if you required.