Project/beatrice.salavastru (#1259)

* Update Laser Harp project documentation

* Fix laser harp image references

* Fix laser harp image references again

* Fix laser harp image references final

* Rename laser harp images to lowercase

Author: beatriceelena5

website/versioned_docs/version-acs_cc/project/2026/beatrice.salavastru/images/laser_harp.webp

@@ -12,12 +12,21 @@ A laser-based musical instrument that converts interrupted light beams into soun
 
 ## Description
 
-A laser harp system with 8 laser beams acting as strings. When a beam is interrupted, a sensor detects the change and the microcontroller generates the corresponding musical note. The sound can be played through a speaker or sent to a computer for external audio playback.
+A laser harp system with 8 laser beams acting as strings. Each beam is aligned with a phototransistor. When the user interrupts one of the beams, the STM32 detects the event and plays the corresponding note through a speaker.
 
 ## Motivation
 
 As someone interested in both music and technology, I want to build an interactive system that translates physical gestures into sound. This project allows me to explore working with optical sensors, handling real-time input from multiple sources, and generating audio signals on a microcontroller. It also gives me the opportunity to integrate hardware and software into a complete system, while creating a visually engaging and intuitive user experience.
 
+## Demo
+
+<iframe width="100%" height="450"
+src="https://www.youtube.com/embed/olEfG4KMzfE"
+title="Laser Harp Demo"
+frameborder="0"
+allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share"
+allowfullscreen></iframe>
+
 ## Architecture 
 
 ![Architecture Diagram](images/laser_harp_architecture.svg)
@@ -32,14 +41,37 @@ Designed and built the wooden frame for the laser harp. Planned the layout of la
 ### Week 12 - 18 April
 Ordered all hardware components from TME and Sigmanortec. 
 
+### Week 4 - 10 May
+Built and tested the electronic circuit using a simple test program. The goal of this stage was to verify that the laser modules, phototransistors, STM32 inputs and audio amplifier worked correctly before integrating the final software.
+
+### Week 11 - 17 May
+Implemented the sample-based audio playback system. The project was changed from simple frequency generation to playback of RAW audio samples stored directly in the STM32 Flash memory. The system now works as a standalone instrument: the audio is played directly through the speaker, without depending on a USB connection to the laptop for sound generation.
 
 ## Hardware
 
-The project uses an STM32 Nucleo-U545RE-Q as the main microcontroller. Laser modules act as light sources, while phototransistors detect beam interruptions. The signals are processed using ADC inputs. An LM386-based audio module drives a speaker for sound output. A toggle switch selects between local audio and external output, while a rocker switch controls power. The system is powered by a 5V supply and mounted on a custom wooden frame.
+The project is built around the **STM32 Nucleo-U545RE-Q**, which reads the sensors and controls the audio output.
+
+The physical harp uses 8 laser modules, each aligned with a phototransistor. The phototransistors are connected to GPIO pins configured as external interrupt inputs. When a laser beam is interrupted, the corresponding input changes state and the STM32 detects the event as a string trigger.
+
+For audio output, the STM32 generates a high-frequency PWM signal on `PB3 / TIM2_CH2`. This signal is passed through a simple analog filtering stage and then sent to an **LM386 audio amplifier**, which drives an 8Ω speaker.
+
+The structure is mounted on a custom wooden frame that keeps the lasers and sensors aligned.
+
+### Hardware Photos
+
+![Laser Harp Front View](images/laser_harp_2.webp)
+
+![Laser Harp Front View - Night](images/laser_harp_1.webp)
+
+![Laser Alignment](images/laser_harp_5.webp)
+
+![Internal Circuit](images/laser_harp_4.webp)
+
+![Internal Circuit](images/laser_harp_3.webp)
 
-<!-- ### Schematics
+### Schematics
 
-Place your KiCAD or similar schematics here in SVG format. -->
+![Circuit Schematic](images/laser_harp.webp)
 
 
 ### Bill of Materials  
@@ -56,7 +88,6 @@ Place your KiCAD or similar schematics here in SVG format. -->
 | Capacitors 100nF | Noise filtering | 6.47 RON |
 | Capacitors 0.1µF | Decoupling | 8.16 RON |
 | Rocker switch | Power ON/OFF | 4.43 RON |
-| Toggle switch (SPDT) | Mode selection | 5.58 RON |
 | Power supply 5V 2A | Power source | 22.61 RON |
 | DC jack connector | Power connection | 3 RON |
 
@@ -66,13 +97,13 @@ Place your KiCAD or similar schematics here in SVG format. -->
 
 | Library | Description | Usage |
 |---------|-------------|-------|
-| [embassy-stm32](https://github.com/embassy-rs/embassy) | STM32 HAL for Embassy | Used for GPIO, ADC and timers/PWM |
-| [embassy-executor](https://github.com/embassy-rs/embassy) | Async task executor | Runs the main application logic |
-| [embassy-time](https://github.com/embassy-rs/embassy) | Timekeeping and delays | Used for timing and sensor polling |
-| [embedded-hal](https://github.com/rust-embedded/embedded-hal) | Hardware abstraction layer | Standard interface for peripherals |
-| [defmt](https://github.com/knurling-rs/defmt) | Lightweight logging framework | Used for debugging and logging |
-| [defmt-rtt](https://github.com/knurling-rs/defmt) | RTT logging transport | Sends logs to the PC |
-| [panic-probe](https://github.com/knurling-rs/probe-run) | Panic handler | Used for debugging crashes |
+| [embassy-stm32](https://github.com/embassy-rs/embassy) | STM32 HAL for Embassy | Used for GPIO/EXTI input handling, PWM audio output, timer configuration and clock setup |
+| [embassy-executor](https://github.com/embassy-rs/embassy) | Async task executor | Runs the main application and the separate laser string monitoring tasks |
+| [embassy-time](https://github.com/embassy-rs/embassy) | Timekeeping and delays | Used for sensor cooldowns and precise audio sample timing |
+| [embassy-sync](https://github.com/embassy-rs/embassy) | Synchronization primitives | Provides the channel used to send triggered note indices from sensor tasks to the audio loop |
+| [defmt](https://github.com/knurling-rs/defmt) | Lightweight logging framework | Used for debug and status messages |
+| [defmt-rtt](https://github.com/knurling-rs/defmt) | RTT logging transport | Sends debug logs from the board to the PC |
+| [panic-probe](https://github.com/knurling-rs/probe-run) | Panic handler | Reports crashes through the debug probe |
 
 ## Links