eecs270.org

Project 2B: Renee

Project 2A: Robbie

Due Date: September 25, 2026 at 11:59 PM

Before Starting

Helpful resources:

• Combinational Verilog Reference
• Comparators: Session 4: Positive Binary Numbers.

Starter Files

• Project2B.v
• TestBench2B_tb.v
• Renee.v
• ReneeAction.v
• unsignedComp.v
• wave2B.do

Design Specification

Renee is a more advanced robot than Robbie. She has two beacon sensors that provide distance information, four bumper sensors that detect collisions, and wheels that can move in reverse in addition to going forward.

Figure 1: Project 2B Interface, module decomposition, and module instantiation graph.

Sensors and Wheels

1. Beacon sensors: Renee has two sensors aimed at her left and right. Each sensor returns a 3-bit unsigned number indicating signal strength. The higher the value, the stronger the signal (7 is strongest, 0 is weakest).
2. Bumper sensors: Renee has four bumper sensors (front, back, left, right). They are active low: they return 0 if Renee has bumped something in that direction, 1 otherwise.
3. Wheels: Renee’s wheels can move forward (F), reverse (r), or stop (S). Each wheel’s action is displayed on a HEX display:

Renee’s Actions

Table 1 shows the actions Renee can perform and the corresponding wheel states.

Action	Left Wheel	Right Wheel
Forward	F	F
Left	S	F
Right	F	S
Stop	S	S
Left Back	S	r
Right Back	r	S
Reverse	r	r

Table 1: How Renee uses her wheels to perform her actions.

Behavior Rules

Renee should head in the direction of the sensor with the strongest signal (highest value). If both signals are the weakest possible (0), Renee should stop. If the two signals are the same but not the weakest possible, Renee should go forward.

The beacon sensors are ignored if Renee has hit something: in that case, her first priority is to move away from the obstacle. If any of her bumpers detect a collision, she should follow these rules:

1. Only front bumper: Reverse
2. Only back bumper: Forward
3. Only left bumper: Right back
4. Only right bumper: Left back
5. Only left and front bumpers: Right back
6. Only right and front bumpers: Left back
7. Only left and back bumpers: Right
8. Only right and back bumpers: Left
9. Any two bumpers on opposite sides (front and back, left and right): Stop

Renee Module Interface

Net	Size	Direction	Description
ls	3 bits	Input	Left beacon sensor signal strength (higher = stronger)
rs	3 bits	Input	Right beacon sensor signal strength (higher = stronger)
lb	1 bit	Input	Left bumper sensor (active low)
rb	1 bit	Input	Right bumper sensor (active low)
fb	1 bit	Input	Front bumper sensor (active low)
bb	1 bit	Input	Back bumper sensor (active low)
lwa	7 bits	Output	Left wheel action (displayed on HEX1)
rwa	7 bits	Output	Right wheel action (displayed on HEX0)

Top-level: Project2B Module

This module connects Renee to the FPGA pins. Create temporary wires called sw_bus [2:0] and assign them to SW and use those.

Net	Direction	Physical Description	Correspondence to Renee
SW[2:0]	Input	rightmost 3 switches	rs (right beacon sensor)
SW[6:4]	Input	left-center 3 switches	ls (left beacon sensor)
KEY[0]	Input	rightmost button	bb (back bumper)
KEY[1]	Input	second button	fb (front bumper)
KEY[2]	Input	third button	rb (right bumper)
KEY[3]	Input	leftmost button	lb (left bumper)
HEX1[6:0]	Output	left 7-segment display	lwa (left wheel action)
HEX0[6:0]	Output	right 7-segment display	rwa (right wheel action)

Design Notes and Hints

• Renee’s design may be implemented using behavioral Verilog (unlike Robbie).
• You can use Boolean expressions directly, e.g. assign a = b & c | d;.
• Allowed Boolean operators:

Logical Operation	Verilog
NOT	~, !
AND	&
OR	\|
XOR	^
XNOR	~^

• You can also use the ternary operator (similar to C):
  • value = condition ? value1 : value2;
  • If condition is true, value = value1, else value = value2.
  • condition, value1, and value2 can be Boolean expressions.
• You CANNOT use arithmetic operators (+, -, integer negation), relational operators (<, >, ==), or if statements.
• Module unsignedComp should implement unsigned 3-bit comparison. Given 3-bit unsigned numbers A and B, produce three outputs: A=B, A<B, and A>B. Modify the magnitude comparator from lecture 6.
• Module ReneeAction should display the three wheel actions (F, r, S) on the HEX display.
• With 10 inputs, a “flat” design is not advisable. Decompose the controller into a hierarchy of smaller design units that have fewer inputs.
• The bumper sensors detect a collision if the corresponding KEY is pressed (KEYs are active low).
• LabsLand KEY note: The default LabsLand web interface does not allow multiple KEYs to be pressed simultaneously. An alternative input method uses the computer keyboard: numbers 0, 1, 2, and 3 correspond to KEY[0], KEY[1], KEY[2], and KEY[3].

Testbench

Your testbench for Renee (TestBench2B_tb.v) will be scored on the Autograder for test coverage. Your tests receive points for detecting specific input combinations that expose potential bugs in a design. Read the Renee specifications carefully to pick meaningful test cases. Thorough tests improve the chance of catching mutants.

Your testbench must instantiate the Renee module, not Project2B. Build off the starter file, which includes an example test case.

Deliverables

File Name	Task	Testing Process	Grading Process
Renee.v	Implement Renee controller module	ModelSim	Autograder
ReneeAction.v	Implement wheel action display module	ModelSim	Autograder
unsignedComp.v	Implement 3-bit unsigned comparator	ModelSim	Autograder
TestBench2B_tb.v	Write test cases for Renee module	ModelSim	Autograder
Project2B.v	Connect Renee to FPGA inputs	LabsLand	Autograder

To ensure that your design works with the Autograder, do not modify file names, module names, or interfaces for any of the starter files. All files must be submitted to the Autograder for grading and feedback.