you wish to write a robotic arm controller. The controller has one motor for each of the five fingers (the pinky is finger 0 and the thumb is finger 4, with others in order). Our hardware uses a scheme called memory-mapped I/O, whereby the hardware intercepts accesses to particular memory locations and interprets them as signals to the hardware device instead of RAM accesses (thus, these addresses do not correspond to reads/writes of memory, which might not even exist at these addresses).

Arm Users Guide

The arms API supports the following operations (and more):

Initialize: write the integer 0 to memory location 0xFFD41230. This will also close all fingers com- pletely.

Ready: Every initialization operation must be followed by this (once) to ensure that the arm is ready to receive commands. The arm clears bit 4 of memory location 0xFFD41234 after it has initialized all its motors and it is ready to receive instructions. In other words, the program must wait for this bit to become 0 before proceeding.

Open finger k by .01 radians: set bit k (0 k 4) of memory location 0xFFD41238. The upper 16 bits (i.e., k16) do not map to any I/O devices (and may thus be corrupted as you wish).

Close finger k by .01 radians: set bit k+5 (0 k 4) of memory location 0xFFD41238.

Due to mechanical issues (since motors are far slower than computers), successive openings of the same finger

must be separated by at least 3 ms., to avoid motor slippage.

Assignment

Draw a CFG and write a MIPS program to do the following:

1. Open the index finger completely (i.e., 3.14 radians)

2. Close the index finger exactly half way while opening the thumb also exactly half way. You wish to do these two fingers in interspersed manner, not one after the other in other words, this means you should close the index finger by .01 radians, then open the thumb by .01 radians, before closing the index finger more.

Since we dont yet have a way to implement time delays, you can simply write delay n as an instruction to indicate a delay of n s.

The same conventions/rules as on the previous homework apply, but you may also use the pseudoinstructio li if you want, and of course the branch-related instructions (but not pseudoinstructions). Submissions without a CFG will not be graded (and it makes no sense to not do the CFG first).