👩‍🎓PCEP Python Prep

Description

This flexible activity series is designed to help students learn foundational Python programming concepts while controlling a four-motor rover. Aligned with the PCEP-30-02 Certified Entry-Level Python Programmer exam, each self-contained activity focuses on a specific Python topic—such as variables, control flow, loops, data collections, and functions—while applying the concept to real rover movement. Students modify a single function in a provided rover control program to experiment with code and immediately observe the physical results on the robot. Each lesson pairs a clear programming objective with guided code examples, TODO challenges, and real-world rover testing. Instructors can mix and match activities or run them sequentially to fit different schedules, making the course adaptable for short workshops, multi-day camps, or full introductory Python classes.

Overview

This guide covers:

• Generating PWM commands for the ROV.

• Understanding how PWM settings affect motor drive and direction.

• Running user-generated Python using LLM output based on guided input.

In order to run python, you will need to have an IDE and python compiler. If desired, you can use Visual Studio Code Code on your computer.

Follow this link https://code.visualstudio.com/docs/setup/setup-overview and use the steps related to your operating system.

Once you have the IDE installed, follow these instructions to install python, https://code.visualstudio.com/docs/python/python-tutorial.

Bleak library

• This library must be installed first https://github.com/hbldh/bleak

• From the command prompt run: Run “pip install bleak”

RoverLLM.py

The activities in this lesson are based on the contents of this file. When prompted below, you can use the copy feature to save a copy of the file to your device

import asyncio
import gc
from bleak import BleakClient, BleakScanner

DEVICE_NAME = "ROV_7446B3EA794D"
MAILBOX_CHARACTERISTIC = "0000ffd1-0000-1000-8000-00805f9b34fb"
COMMAND_CHARACTERISTIC = "0000ffd2-0000-1000-8000-00805f9b34fb"

client = None  # Global client variable

async def find_device_by_exact_name(name):
    print("Scanning for BLE devices...")
    devices = await BleakScanner.discover(timeout=10.0)
    for d in devices:
        if d.name == name:
            print(f"Found device: {d.name} ({d.address})")
            return d.address
    print(f"No device found with name: {name}")
    return None
    
async def initialize():
    await MoveMotors(-1, -1, -1, -1)
    await MoveMotors(0, 0, 0, 0)
    
async def MoveMotors(m1, m2, m3, m4):
    motors = [max(-100, min(100, val)) & 0xFF for val in (m1, m2, m3, m4)]
    payload_mailbox = bytearray(motors)
    payload_command = bytearray([0x13, 0x00])

    await client.write_gatt_char(MAILBOX_CHARACTERISTIC, payload_mailbox, response=False)
    await client.write_gatt_char(COMMAND_CHARACTERISTIC, payload_command, response=False)
    print(f"Motors moved: [{m1} {m2} {m3} {m4}]")

async def StartProgram():
    print("Move Forward at 50% for 2 seconds")
    await MoveMotors(50, 50, 50, 50)
    await asyncio.sleep(2)
    print("Stop")
    await MoveMotors(0, 0, 0, 0)
    await asyncio.sleep(2)

async def main():
    global client
    address = await find_device_by_exact_name(DEVICE_NAME)
    if not address:
        return

    client = BleakClient(address)
    try:
        await client.connect()
        if not client.is_connected:
            print("Failed to connect.")
            return
        print(f"Connected to {DEVICE_NAME}")

        await initialize()
        await StartProgram()

    except Exception as e:
        print(f"Error: {e}")
    finally:
        try:
            print(f"Attempting disconnect... connected: {client.is_connected}")
            await client.disconnect()
            await asyncio.sleep(1)
            gc.collect()
            print("Disconnected and cleaned up.")
        except Exception as e:
            print(f"Error during disconnect: {e}")

if __name__ == "__main__":
    asyncio.run(main())

Each activity aligns with topics from the PCEP‑30‑02 Certified Entry‑Level Python Programmer exam.

This course teaches Python programming while controlling a four‑motor rover.

In every activity:

• Save the file as activityX.py • Run the program using Visual Studio Code • Modify or debug the StartProgram() function • Do NOT modify the rover Bluetooth code

You will fix bugs, complete missing code, and extend programs.

---

Running Programs in Visual Studio Code

1. Open Visual Studio Code

2. Open your rover project folder

3. Create a new file (example: activity1.py)

4. Paste the rover base program into the file

5. Modify StartProgram()

6. Run the program

Open the terminal:

Terminal → New Terminal

Run:

python activity1.py

---

Rover Motor Command

The rover moves using:

await MoveMotors(m1, m2, m3, m4)

Values range -100 to 100

Value	Meaning
100	Full Forward
50	Half Forward
0	Stop
-50	Reverse
-100	Full Reverse

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SECTION 1 – Python Fundamentals

---

Activity 1 – Instructions and Comments

Objective

Learn:

• Python instructions • indentation • comments

Save

activity1.py

Starter Code

async def StartProgram():

    # TODO move rover forward

    await MoveMotors(50,50,50,50)

    # TODO wait 2 seconds


    # TODO stop rover

Student Task

Complete the program so the rover:

1. Moves forward 2 seconds

2. Stops

3. Waits 1 second

Add comments explaining the code.

---

Activity 2 – Variables

Objective

Learn:

• variables • integers • storing values

Save

activity2.py

Starter Code

async def StartProgram():

    speed = 50

    await MoveMotors(speed,speed,speed,speed)
    await asyncio.sleep()

    await MoveMotors(0,0,0,0)

Student Task

Fix the missing value so the rover moves forward 2 seconds.

Add a variable called:

duration

---

Activity 3 – Operators (Debugging)

Objective

Learn:

• operators • modifying variable values

Starter Code (Bug)

async def StartProgram():

    speed = 10

    for i in range(5):

        await MoveMotors(speed,speed,speed,speed)
        await asyncio.sleep(1)

        speed + 10

Student Task

Fix the bug so speed increases each loop.

Expected speeds:

10 20 30 40 50

---

SECTION 2 – Control Flow

---

Activity 4 – Conditional Statements

Objective

Learn:

• if • elif • else

Starter Code

async def StartProgram():

    command = input("Enter command: ")

    if command == "forward":
        await MoveMotors(50,50,50,50)

    # TODO add backward command

    await asyncio.sleep(2)

    await MoveMotors(0,0,0,0)

Student Task

Add commands:

backward
left
right

---

Activity 5 – Loops

Objective

Learn:

• for loops • repetition

Starter Code

async def StartProgram():

    for i in range(1):

        await MoveMotors(50,50,50,50)
        await asyncio.sleep(2)

        await MoveMotors(0,0,0,0)

Student Task

Fix the loop so the rover repeats the movement 5 times.

---

Activity 6 – Movement Pattern

Objective

Learn:

• combining loops with movement

Starter Code

async def StartProgram():

    for i in range(4):

        await MoveMotors(50,50,50,50)
        await asyncio.sleep(2)

        # TODO add right turn

    await MoveMotors(0,0,0,0)

Student Task

Add turning code so the rover drives in a square.

---

SECTION 3 – Data Collections

---

Activity 7 – Lists

Objective

Learn:

• lists • iterating through lists

Starter Code

async def StartProgram():

    speeds = [20,40,60]

    for s in speeds:

        await MoveMotors(s,s,s,s)
        await asyncio.sleep(1)

Student Task

Add more speeds:

10
30
50
70

---

Activity 8 – Movement Sequences (Debugging)

Starter Code (Bug)

async def StartProgram():

    moves = [
        (50,50,50,50),
        (50,-50,50,-50)
    ]

    for m in moves:

        await MoveMotors(m)

Student Task

Fix the program so the rover executes the sequence.

Hint: MoveMotors() requires 4 arguments.

---

Activity 9 – Dictionaries

Objective

Learn:

• dictionaries • key/value lookups

Starter Code

async def StartProgram():

    commands = {
        "forward": (50,50,50,50),
        "stop": (0,0,0,0)
    }

    cmd = input("Enter command: ")

    m = commands[cmd]

    await MoveMotors(m[0],m[1],m[2],m[3])

Student Task

Add commands:

backward
left
right

---

SECTION 4 – Functions

---

Activity 10 – Functions

Objective

Learn:

• defining functions • parameters

Starter Code

async def DriveForward(speed,time):

    # TODO complete function


async def StartProgram():

    await DriveForward(40,2)

Student Task

Finish the function so the rover:

1. Moves forward

2. Waits

3. Stops

---

Activity 11 – Exception Handling

Objective

Learn:

• try • except • preventing program crashes

Starter Code

async def StartProgram():

    speed = int(input("Enter speed: "))

    await MoveMotors(speed,speed,speed,speed)

Student Task

Add exception handling so the program does not crash if the user enters text.

---

Activity 12 – Command Parser

Objective

Learn:

• strings • text commands • program logic

Starter Code

async def StartProgram():

    command = input("Enter command: ").lower()

    if command == "forward":
        await MoveMotors(50,50,50,50)

    elif command == "backward":
        pass

    elif command == "left":
        pass

    elif command == "right":
        pass

Student Task

Complete the commands so the rover responds correctly.

Add a command:

spin

---

Final Challenge – Rover Patrol

Create a new file:

final_mission.py

Write a program that:

1. Drives in a square

2. Spins in place

3. Returns to the starting point

4. Stops

Use:

• loops • functions • conditionals • lists