Enhance documentation with detailed image descriptions for clarity on embedded programming concepts and application stacks.

Author: madeline-underwood

content/learning-paths/embedded-and-microcontrollers/arduino-pico/_index.md

@@ -3,6 +3,7 @@ title: Embedded programming with Arduino on the Raspberry Pi Pico
 
 who_is_this_for: This is an introductory topic for software developers interested in embedded programming.
 minutes_to_complete: 60
+description: Learn how to build a motion-detection device with Raspberry Pi Pico (RP2040 Cortex-M0+) using Arduino IDE, PIR sensors, and interrupt-driven programming on baremetal.
 
 learning_objectives: 
     - Understand the basics of embedded programming

content/learning-paths/embedded-and-microcontrollers/arduino-pico/app_stack.md

@@ -12,7 +12,7 @@ layout: "learningpathall"
 
 Application developers will be familiar with this traditional computing stack, whether their target devices are desktops, mobile phones, or the cloud, it would be the same. 
 
-![Traditional stack](_images/traditional_stack.png)
+![Diagram showing the traditional application computing stack with four layers from bottom to top: hardware, firmware/BIOS, operating system, and application. The firmware layer provides hardware abstraction that allows a single OS image to run on different hardware configurations, a key difference from embedded systems.#center](_images/traditional_stack.png)
 
 ## Hardware
 

content/learning-paths/embedded-and-microcontrollers/arduino-pico/arduino_sketch.md

@@ -246,7 +246,7 @@ If successful, you should see the LED on your board light up. If you wave your h
 
 You can further check that your code is running properly by opening the `Serial Monitor` from the `Tools` menu of the Arduino IDE. There you should see all of the output messages, including count of detected motion events, coming from your sketch.
 
-![Debug output](_images/output.webp)
+![Screenshot of the Arduino IDE Serial Monitor window displaying debug messages from the motion detection sketch. The output shows repeated "Motion detected" messages followed by motion event counts, confirming that the PIR sensor is triggering correctly and the sketch is processing the interrupts.#center](_images/output.webp)
 
 Congratulations! You have successfully programmed your microcontroller and built a working, if simple, smart device. 
 

content/learning-paths/embedded-and-microcontrollers/arduino-pico/arm_embedded.md

@@ -12,7 +12,7 @@ layout: "learningpathall"
 
 Now that you know the differences between application and embedded programming, as well as the differences in the hardware and software stack, it's time to take your first steps into embedded software development!
 
-![Arm Embedded stack](_images/embedded_arm_stack.png)
+![Diagram showing the typical Arm embedded software stack with three layers: Cortex-M CPU at the bottom hardware layer, Mbed OS RTOS in the middle, and C application code with supporting libraries at the top. This illustrates the standard architecture for Arm microcontroller projects where the RTOS sits directly on hardware without a firmware abstraction layer.#center](_images/embedded_arm_stack.png)
 
 A typical embedded project for Arm devices looks like this. For microcontrollers, you'll have a CPU in the Cortex-M family and, as your RTOS, you'll use something like Mbed OS, which is provided by Arm and used by default in Arm Developer Studio and Keil MDK.
 
@@ -26,7 +26,7 @@ As you know, these small, cheap, development prototyping boards have been around
 
 But they're so much more than just a toy for making lights flash. They're a really great way to get started with embedded programming!
 
-![Arduino stack](_images/embedded_arduino_stack.png)
+![Diagram showing Arduino's simplified embedded stack with Cortex-M0+ CPU at the hardware layer, Arduino core package in the middle providing hardware abstraction, and Arduino sketch written in C++ at the application layer. This shows how Arduino makes embedded development more accessible by hiding low-level hardware details behind the core package.#center](_images/embedded_arduino_stack.png)
 
 The latest generations of Arduino use Arm Cortex-M microprocessors, such as the Cortex-M0+ in the Arduino Nano RP2040, making that more powerful and capable than before, while still providing a very simple and straightforward programming experience.
 

content/learning-paths/embedded-and-microcontrollers/arduino-pico/embedded_stack.md

@@ -12,7 +12,7 @@ layout: "learningpathall"
 
 While the embedded computing stack looks similar to an application stack, there are some important differences.
 
-![Embedded stack](_images/embedded_stack.png)
+![Diagram showing the embedded computing stack with hardware at the bottom, RTOS in the middle, and application at the top. Unlike traditional application stacks, there is no firmware layer abstracting the hardware, meaning embedded software must be built specifically for the target hardware and include all necessary drivers.#center](_images/embedded_stack.png)
 
 ## Hardware