CE 433 Embedded Devices

HW1: Vivado and Gvim Basics
Name: Lucien Verrone
Email: ljverrone@fortlewis.edu

Introduction:

This assignment was a more detailed intro into Gvim and Vivado, along with the workflow that goes between both. Tasks included writing code in Gvim modeled off of the code shown in class, and creating test benches to simulate in Vivado.

Task 1:

Task one was to recreate examples 2.1, 2.2, and 2.3 from class. These examples also needed a test bench and simulations in Vivado to verify the integrity of the code. These examples are all modeling the same system.
System that is being modeled by examples 2.1, 2.2, and 2.3. It has an and gate and or gate leading to a xor gate and a not gate.
Figure 1: System that is being modeled by examples 2.1, 2.2, and 2.3.

Example 2.1 models each gate individually, with the and and or gates being coded first and the xor and not gates being coded with those results. The test bench simply uses inputs and outputs one and two to test the model in a simulation.
Example 2.1 simulation.
 2.1 Gvim code
Figure 2: Example 2.1's Gvim code and Vivado simulation.

Example 2.2 models the and and or gates with the xor and not gates. The test bench uses the same inputs and outputs as example 2.1.
2.2 simulation
 2.2 Gvim code
Figure 3: Example 2.2's Gvim code and Vivado simulation.

Example 2.3 models the and and or gates with the xor and not gates only after the inputs are changed. This was done by declaring the output assignments as always processes dependant on inputs one and two. The inputs also have to be declared and registers aThe test bench uses the same inputs and outputs as example 2.1 and 2.2.
2.3 simulation
 2.3 Gvim code
Figure 4: Example 2.3's Gvim code and Vivado simulation.


Task 2:

Task two was to demonstrate the difference between blocking and non-blocking assignment using example 2.4. This was done using an initial value and a clock variable, with an always process activated by the rising edge of the clock that controlls the blocking and non-blocking assignments. The clock was assigned and reassigned, however I think there is a more efficient way to create a clock like this I missed.
2.4 Simulation
 2.4 Gvim code
Figure 5: Example 2.4 and Vivado simulation. y[3:5] represent the nonblocking assignments.

Task 3:

Task three was to recreate example 2.5 which demonstrates timing delays. There is one 20ns delay in the model itself, and four 100ns delays in the test bench.
2.5 Simulation
 2.5 Gvim code
Figure 6: Example 2.5 and Vivado simulation. The 20ns delay can be seen in the red portion of out2 in the simulation.

Task 4:

Task four was to move the 20ns delay a line up in example 2.5 and simulate the result.
2.5 with moved 20ns delay simulation
 2.5 Gvim code with moved 20ns delay
Figure 7: Example 2.5 with 20ns delay moved and Vivado simulation. The 20ns delay can be seen to have moved to out1.

Task 5:

Task five was to hand draw an example timing diagram.
Hand drawn timing diagram
Figure 8: Hand drawn timing diagram.

Task 6: 

Task six was to recreate example 2.6. Example 2.6 demonstrates hierarchial modules. Or and and gates are seperated into their own seperate modules, which are then imported into the main module, which is then imported into the test bench.
2.6 simulation
 2.6 Gvim code
Figure 9: Example 2.6 and Vivado simulation.

Discussion:

This assignment familiarized me further with Gvim and was my first time using Vivado. I found myself becoming very comfortable with Gvim commands and Vivado simulations didn't cause any issues. Beyond this, the different approaches from each example taught me something new. Example 2.1 and 2.2 show the differences between using assign versus not, along with combining functions. Example 2.3 taught me to use always processes, a skill that is then used to create a loop to show the difference between blocking and non-blocking in example 2.4. Example 2.5 introduced me to the delay  an repeat commands. Finally, example 2.6 showed hierarchial structure for modules and the process of importing nested modules. Overall, this assignment has made me feel better prepared to handle coming labs and assignments using Gvim and Vivado.