VAS gRPC data structure for logging on RPI

[nundinir]

The data needs to be sent either as a dictionary/array of:

• current torque to command
• buttons mapped to corresponding current $-values

May need to make a custom dictionary type for grpc communication

[nundinir]

There should also be 2-way communication enabled between the RPI and the GUI. Specifically, the RPI should send a response upon start-up/file-naming that contains the trial and presentation number (e.g. T1P2) so we don't have to change it at both locations.

This Trial and Presentation number combo is used to dictate which randomized set of torques are mapped to the VAS GUI buttons.