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There were several levels of software involved in the project. The
functionality of the nintendo 64 controller and LCD display were all done
in hardware. When the hardware finished gathering all the necessary data
it was stored in a global variable. Then an interrupt flag was triggered
calling the ISR. The ISR then parsed the data stored in the global variable
and converted it to a standard ISA that we agreed upon. Since we currently
have no use for 32-bit instructions, we sent 4 8-bit commands at a time.
The 32-bit instructions maybe useful in the future as we scale this car
to handle more features.
After the parsing was finished, the sendTo555 function was call trigger
a series of sends and acknowledgements. RS232 can only send 8-bits at a time
so a series of 4 transactions were required in order to send all 32-bits
of an instruction. Then after the data arrived at the MPC55 end,
the opcodes were parsed and the appropriate motor and/or servo was driven.
The actual servo and motor driving functionality was provided as C functions
by freescale and enabled us to simply call PWM functions in with several
arguements in order to drive the servos and motors.
The following is a flow chart showing the flow of the program:
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