Gcode I2C SPI Commands

Would it be worthwhile to add commands to Reprap Gcode for I2c and SPI interfaces.
The RAMPS board brings these out from Arduino.

This opens the possibilities for controlling additional hardware right from Gcode file...

Please discuss

I am not sure how you would implement it from Gcodes?

There is simply too many devices out there. Although they may follow the same communication protocol, that doesn't mean that they have uniform commands.

Perhaps you have some ideas on what devises you envisage being connected to the board?

Thanks for entertaining this idea.

I do realize the amount of devices and variations and the complexities, and yes all devices and all mode permutations cant be supported.
I am envisioning a single master only setup...

I was thinking along the lines of something along the following lines where one can
say a issue a write command to buzzer, LED matrix BOARD, or LCD board,Fans,
Or read and write commands to say externally independent heaters(chambers print bed extruders with their own closed loop monitors).

These commands to start and end of gcode and perhaps wouldnt need to add these changes to the arduino firmware.

something like
M I2CAddress Data2Write : This will write the data to the address
M I2CAddress LoopReadTillTempReached :This will keep checking the Devices with where Temperature ha to be read the value and continue afterwords. The desire is to have something similar like the M109 command where it waits till the temperature is reached