Differences

This shows you the differences between two versions of the page.

--- report:dvp [2026/04/16 15:21] – [Prototype] team5
+++ report:dvp [2026/04/26 19:00] (current) – [7.4.2 Smart System] team5
@@ Line 50: / Line 50: @@
-Phase 1:
+**Phase 1: **
 On the metro, you touch a handrail. The handrail is a tube that contains a sensor and a light. The spot where you touch the pole lights up in a color: your color. Your color then travels visibly through the pole up to the ceiling of the metro.
 On the ceiling of the metro there are LEDs. Your color appears on the ceiling through these LEDs. If another person touches a different pole, their color also appears on the ceiling, and your colors blend together.
-Phase 2:
+**Phase 2:**
 Near the exit doors, there is a QR code that creates a bridge from the visual interaction to a more personal level. After scanning it, a minimalist webpage opens with two main options: “Send” or “Read”
@@ Line 73: / Line 73: @@
-== 7.4.1 User Interface for the Message Page ==
+**User Interface for the Message Page**
+<color #ed1c24>Figure {{ref>fig:Mockups_Message_Page}} ...</color>
+<WRAP centeralign>
 <figure fig:Mockups_Message_Page>
 {{:report:bildschirmfoto_2026-03-29_um_10.40.20.png|}}
 <caption>Mockups Message Page</caption>
 </figure>
+</WRAP>
  The web interface, accessible via QR code, is designed in a minimalist style. After scanning the QR code, users are redirected to the web application's landing page. The CONNECT logo takes center stage here, accompanied by two clickable buttons that lead to the subsequent sections. Within the app, users can choose between composing a message for others or viewing messages written by the community. Our primary focus was to keep the application as simple as possible; we wanted to ensure that both young and old users can navigate it effortlessly. By eliminating the need for logins or complex navigation, we’ve made the experience accessible and time-efficient for everyone.
+=== 7.4.1 Structure ===
+Figures {{ref>fig:initial_drawing}}, {{ref>fig:final_drawings}}, and {{ref>fig:final_final_drawings}} present the evolution of the structural design across successive iterations. Each version reflects an increase in geometric precision, component integration, and manufacturability, progressing from early conceptual layouts to a fully defined enclosure suitable for system integration.
-== 7.4.2 Design System ==
+<WRAP centeralign>
-<figure fig:styleguide>
-{{:report:styleguide.png|}}
-<caption>Style guide</caption>
-</figure>
-To ensure a consistent user experience and streamline the development process, our project is built upon a custom-developed, comprehensive Design System. This serves as the central framework for all visual and functional interfaces within our web application.
-Importance of the Design System for our Project
-A unified design system is essential to the success of our product for the following reasons:
-- Consistency: Users can recognize the brand instantly. A cohesive appearance builds trust and conveys professionalism.
-- Development Efficiency: By defining reusable components, there is no need to "reinvent the wheel" for every new feature.
-- Scalability: New functions can be integrated seamlessly because design rules (layout grids, spacing, colors) are already established.
-- Accessibility: By strictly defining contrasts and font sizes, we ensure that the application remains accessible to all target groups.
-**Core Components of our Style Guide**
-**Color Palette**
-Our color strategy is deeply rooted in the application's functionality.
-- Contextual Derivation: The primary colors and their respective shades were derived directly from metro line branding. This ensures high recognition and creates an immediate visual link to the urban mobility context.
-- Color Hierarchy: We utilize a system of primary, secondary, and accent colors, complemented by a grayscale palette for backgrounds and text to effectively manage visual hierarchy.
-**Typography**
-- Typographic Scale: We use a fixed scale for font sizes, line heights, and weights.
-- Application: This scale is applied consistently across all touchpoints from large headlines for orientation to optimized body text for detailed information. This guarantees a harmonious typographic appearance on all devices.
-**UI Component Library**
-A key part of the system is the library of reusable elements:
-- Modularity: All elements, such as buttons and input fields, were developed modularly.
-- Optimization: Components are specifically optimized for web application requirements (e.g., clear click targets, feedback states like hover or disabled).
-- Reusability: Developers can easily access these components, which reduces the margin for error and seamlessly translates the design into the technical implementation.
-The Design System forms the visual foundation of our project. It bridges the gap between aesthetic brand identity and technical precision, ensuring that the web application is perceived as a unified, professional, and cohesive piece of work.
-=== Structure ===
-Figures {{ref>fig:initial_drawing}}, {{ref>fig:final_drawings}} and {{ref>fig:final_final_drawings}} present all versions of structural drawings where each one has an incremental increase in quality and detail as project moved forward.
 <figure fig:initial_drawing>
-{{ :report:page_1.png?nolink | Initial drawing}}
+{{ :report:page_1.png?direct&800  | Initial drawing}}
 <caption>Initial structural drawing</caption>
 </figure>
+</WRAP>
+<WRAP centeralign>
 <figure fig:final_drawings>
-{{ :report:final_drawing.png?nolink  | Intermediate drawing}}
+{{ :report:final_drawing.png?direct&800 | Intermediate drawing}}
 <caption>Intermediate structural drawing</caption>
 </figure>
+</WRAP>
+<WRAP centeralign>
 <figure fig:final_final_drawings>
-{{ :report:final_drawing_v3.png?nolink | Final drawing}}
+{{ :report:final_drawing_v3.png?direct&800 | Final drawing}}
 <caption>Final structural drawing</caption>
 </figure>
+</WRAP>
+The transition from preliminary sketches to detailed structural drawings (see Figure {{ref>fig:final_final_drawings}}) marked a key milestone in the project. At this stage, the spatial constraints of all subsystems were clearly defined, including the placement of electronic components, routing of wiring, and mounting strategy. This enabled the development of a specialized Bill of Materials (BoM), as presented in Table {{ref>components_ideal}}, where component selection was directly informed by mechanical, environmental, and regulatory requirements.
+Three primary constraints shaped the structural design: enclosure material selection and regulatory compliance, integration of communication hardware within a constrained geometry, and accommodation of power distribution components.
+ **Enclosure Material and Regulatory Complianc**
+The enclosure design aims to ensure compatibility with metro environments, where safety requirements are critical. In particular, EN 45545-2 imposes strict constraints on material flammability and smoke emission. Initial concepts considered PLA due to its accessibility for rapid prototyping. However, due to its poor fire resistance, it is not suitable for real deployment. For this reason, the design considers Polyamide (PA) Rail as a future implementation material, as it meets railway fire safety standards. At the current prototype stage, this requirement is addressed conceptually, with the enclosure geometry designed to be compatible with such materials, while fabrication remains focused on accessible prototyping methods.
+ **Mechanical Integration and Mounting**
+The structural design defines the placement and fixation of internal components, including PCBs, sensors, and power elements. Mounting points are incorporated to allow secure attachment of the PCBs using standard fastening methods (e.g., screws and standoffs), ensuring mechanical stability under vibration and movement conditions typical of public transport environments. The enclosure also considers accessibility for assembly and maintenance, allowing access to connectors and internal components without requiring complete disassembly.
-The completion of the structural drawings (see Figure {{ref>fig:final_drawings}}) marked a critical milestone, enabling the transition from conceptual frameworks to a specialized Bill of Materials (BoM), as detailed in Table {{ref>tab:components_ideal}}. This selection establishes the Connect and share system as a commercial-grade implementation in which safety and reliability are non-negotiable requirements. Three primary technical challenges shaped the component selection process: enclosure material and regulatory compliance, communication protocol and signal integrity, and power supply management.
+ **Wiring and Internal Layout Considerations**
+Although detailed cable routing is not fully defined at this stage, the structural design accounts for basic wiring requirements. Dedicated entry and exit points for cables are considered, along with internal space allocation for routing. Particular attention is given to the separation of power and signal lines, in order to reduce potential electrical interference and improve system reliability. These considerations will guide future iterations of the design, where detailed routing and harnessing will be implemented.
-*  I. Enclosure Material and Regulatory Compliance --
+ **Thermal and Environmental Considerations**
-The overarching objective of this phase was to advance beyond laboratory prototypes toward a system fully compliant with rigorous European Union regulations, most critically EN 45545-2, which governs fire protection on railway vehicles. The initial proposal to use standard PLA for enclosures was rejected early in the design process due to its significant fire hazard profile. The design therefore transitioned to a PA Rail (Polyamide) enclosure, a material specifically engineered for railway environments that meets the low-smoke and flame-retardant benchmarks required for operation within subterranean metro infrastructures. Procuring infrastructure-grade hardware proved non-trivial, particularly for the rail-certified housing units, which required engagement with specialized international suppliers. This process exposed a significant technical disparity between consumer-grade components and the certified equipment essential for integration into public transit systems.
+The system includes components such as DC-DC converters and LED drivers, which generate heat during operation. At this stage, thermal management is addressed through basic passive strategies, including spacing between components and the potential inclusion of ventilation openings in the enclosure. Environmental protection (e.g., against dust and humidity) is considered at a conceptual level, with the enclosure intended to evolve toward a more sealed and robust design in future iterations.
-* II. Communication Protocol and Signal Integrity --
-Metro carriages constitute high-interference electrical environments. High-voltage overhead conductors and traction motors generate substantial Electromagnetic Interference (EMI), which can readily corrupt standard data signals, making protocol selection a critical design decision. The Controller Area Network (CAN) protocol, implemented via the MCP2551 transceiver, was chosen for its inherent use of differential signaling, which provides strong immunity to common-mode noise. This architecture allows the Connect and share system to reject the electrical noise that routinely causes I²C or USB communications to fail in comparable environments. As a direct result, the system achieves stable data transmission between the handrail sensors and the ceiling LEDs even during periods of peak motor acceleration, which represents the most demanding electromagnetic conditions in regular operation.
+The BoM presented in Table {{ref>components_ideal}} reflects the current stage of the design, combining prototyping components with elements selected based on future deployment requirements.
-* III. Power Supply Management --
+While some components (such as enclosure materials) are specified with industrial standards in mind, others are selected to support rapid prototyping and testing. This hybrid approach allows validation of system functionality while maintaining a clear path toward a more robust, deployment-ready solution.
-To address the fluctuating power supply characteristics inherent to rolling stock, an industrial Mean Well DC-DC converter was integrated into the design. Beyond voltage stabilization, this component fulfills a second critical function: it provides regulated outputs at the multiple voltage levels required by the system's heterogeneous hardware, supplying 12 V to the LED strips and 5 V to the microcontrollers, thereby ensuring reliable and consistent operation across all subsystems.
 <WRAP center round box 1100px>
-<table tab:components_ideal>
+<table components_ideal>
 <caption>List of components for the product</caption>
-^ Name ^ Type ^ Supplier & more details ^ Additional notes ^ Price (€) ^ Quantity ^ Total (€) ^
+^ Name ^ Type ^ Supplier & more details ^ Additional notes ^  Price (€) ^  Quantity ^  Total (€) ^
-| Microcontroller | Wemos C3 mini | [[https://mauser.pt/095-1308/seeed-113991054-microcontrolador-seeed-studio-xiao-esp32c3-c-wi-fi-bluetooth-5-0-e-carregamento-de-bateria|Link]] | 1 is main board, others are support ones | 6,20 | 11 | 68,20 |
+| Microcontroller | Wemos C3 mini | [[https://mauser.pt/095-1308/seeed-113991054-microcontrolador-seeed-studio-xiao-esp32c3-c-wi-fi-bluetooth-5-0-e-carregamento-de-bateria|Link]] | 1 is main board, others are support ones |  6.20 |  11 |  68.20 |
-| Box for electronics equipment | PA Rail | [[https://nanovia.tech/en/ref/nanovia-pa-rail/|Link]] | Fire resistant, could not find a portuguese supplier (this one is french) | 69,30 | 2 | 138,60 |
+| Box for electronics equipment | PA Rail | [[https://nanovia.tech/en/ref/nanovia-pa-rail/|Link]] | Fire resistant, could not find a Portuguese supplier (this one is French) |  69.30 |  2 |  138.60 |
-| Copper tape |  | [[https://mauser.pt/095-6889/fita-condutora-de-cobre-adesiva-20mm-20m|Link]] |  | 8,86 | 15 | 132,90 |
+| Copper tape |  | [[https://mauser.pt/095-6889/fita-condutora-de-cobre-adesiva-20mm-20m|Link]] |  |  8.86 |  15 |  132.90 |
-| Pressure sensor | Velostat | [[https://mauser.pt/096-9473/adafruit-1361-folha-de-velostat-piezoresistiva-p-sensores-de-pressao-wearable|Link]] |  | 7,90 | 15 | 118,50 |
+| Pressure sensor | Velostat | [[https://mauser.pt/096-9473/adafruit-1361-folha-de-velostat-piezoresistiva-p-sensores-de-pressao-wearable|Link]] |  |  7.90 |  15 |  118.50 |
-| CAN Transceiver | MCP2551-I-P | [[https://mauser.pt/001-1903/circuito-integrado-mcp2551-i-sn|Link]] | At 26.03 not in stock, email store to check availability | 1,99 | 10 | 19,90 |
+| CAN Transceiver | MCP2551-I-P | [[https://mauser.pt/001-1903/circuito-integrado-mcp2551-i-sn|Link]] | At 26.03 not in stock, email store to check availability |  1.99 |  10 |  19.90 |
-| LED strip with covers | Addressable RGB | [[https://www.amazon.es/dp/B01CNL6K52/ref=asc_df_B01CNL6K52?mcid=2fed6cd8fc303e129f0f7bf9a7df3d53&language=pt_PT&tag=ptgogshpadde-21&linkCode=df0&hvadid=718274527647&hvpos=&hvnetw=g&hvrand=10431677883703446528&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9218545&hvtargid=pla-408656678064&gad_source=1&th=1|Link]] |  | 30,49 | 3 | 91,47 |
+| LED strip with covers | Addressable RGB | [[https://www.amazon.es/dp/B01CNL6K52/ref=asc_df_B01CNL6K52?mcid=2fed6cd8fc303e129f0f7bf9a7df3d53&language=pt_PT&tag=ptgogshpadde-21&linkCode=df0&hvadid=718274527647&hvpos=&hvnetw=g&hvrand=10431677883703446528&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9218545&hvtargid=pla-408656678064&gad_source=1&th=1|Link]] |  |  30.49 |  3 |  91.47 |
-| Power supply (12 V) | DC-DC converter | [[https://www.worten.pt/produtos/modulo-conversor-dc-step-down-36v-72v-para-12v-10a-120w-regulador-de-voltaje-fuente-de-alimentacion-mrkean-5046628495403|Link]] | 2m strips draw 7.2 A at full power (~30 % reserve) | 24,67 | 6 | 148,02 |
+| Power supply (12 V) | DC-DC converter | [[https://www.worten.pt/produtos/modulo-conversor-dc-step-down-36v-72v-para-12v-10a-120w-regulador-de-voltaje-fuente-de-alimentacion-mrkean-5046628495403|Link]] | 2 m strips draw 7.2 A at full power (~30 % reserve) |  24.67 |  6 |  148.02 |
-| Power supply (5 V) | DC-DC converter | [[https://www.worten.pt/produtos/modulo-conversor-dc-72v-para-5v-25a-75w-regulador-de-voltaje-com-caixa-de-aluminio-conversao-buck-mrkean-5046628823572|Link]] |  | 37,15 | 1 | 37,15 |
+| Power supply (5 V) | DC-DC converter | [[https://www.worten.pt/produtos/modulo-conversor-dc-72v-para-5v-25a-75w-regulador-de-voltaje-com-caixa-de-aluminio-conversao-buck-mrkean-5046628823572|Link]] |  |  37.15 |  1 |  37.15 |
-| Wiring, resistors etc. |  | [[https://mauser.pt/104-7036/resistencia-de-filme-metalico-1kr-0-6w-1-2-5x6-8mm|Link]] | Really cheap | 10,00 | 1 | 10,00 |
+| Wiring, resistors etc. |  | [[https://mauser.pt/104-7036/resistencia-de-filme-metalico-1kr-0-6w-1-2-5x6-8mm|Link]] | Really cheap |  10.00 |  1 |  10.00 |
-| Delivery cost |  | Stationary store | To be reviewed | 0 | 1 | 0 |
+| Delivery cost |  | Stationary store | To be reviewed |  0 |  1 |  0 |
-| Total Project Cost |  |  |  |  |  | 764,74 |
+| Total Project Cost |  |  |  |  |  |  764.74 |
 </table>
 </WRAP>
@@ Line 189: / Line 157: @@
-=== Smart System ===
+=== 7.4.2 Smart System ===
-== Hardware ==
+**Hardware**
 Figure {{ref>fig:black_box_diagram}} presents the black box diagram, which includes all the major systems that will be used for our Smart System.
@@ Line 202: / Line 170: @@
 </figure>
 </WRAP>
@@ Line 213: / Line 182: @@
 <table powerbudget1>
 <caption>Power budget table (typical usage)</caption>
-^ Equipment ^ Qty ^ Rail ^ V (V) ^ I per unit (A) ^ I total (A) ^ P (W) ^
+^ Equipment ^  Qty ^  Rail ^  U (V) ^  I per unit (A) ^  I total (A) ^  P (W) ^
-| ESP32-C3 sensor nodes | 10 | 5V | 5 | 0.120 | 1.200 | 6.000 |
+| ESP32-C3 sensor nodes |  10 |  5.0 V|  5 |  0.120 |  1.200 |  6.000 |
-| ESP32-C3 central node | 1 | 5V | 5 | 0.150 | 0.150 | 0.750 |
+| ESP32-C3 central node |  1 |  5.0 V|  5 |  0.150 |  0.150 |  0.750 |
-| CAN transceiver MCP2551 | 10 | 5V | 5 | 0.010 | 0.100 | 0.500 |
+| CAN transceiver MCP2551 |  10 |  5.0 V|  5 |  0.010 |  0.100 |  0.500 |
-| LED strips WS2812B (2m, 120 LEDs each) | 3 | 12V | 12 | 2.400 | 7.200 | 86.400 |
+| LED strips WS2812B (2 m, 120 LEDs each) |  3 |  12.0 V |  12 |  2.400 |  7.200 |  86.400 |
-| Velostat pressure sensors | 15 | 3.3V | 3.3 | 0.001 | 0.015 | 0.050 |
+| Velostat pressure sensors |  15 |  3.3 V |  3.3 |  0.001 |  0.015 |  0.050 |
-| **Total** | | | | | | **93.700** |
+| **Total** | | | | | |  **93.700** |
-| **Total + 25% safety margin** | | | | | | **117.125** |
+| **Total + 25 % safety margin** | | | | | |  **117.125** |
 </table>
 </WRAP>
@@ Line 227: / Line 196: @@
 <table powerbudget2>
 <caption>Power budget table (peak usage)</caption>
-^ Equipment ^ Qty ^ Rail ^ V (V) ^ I per unit (A) ^ I total (A) ^ P (W) ^
+^ Equipment ^  Qty ^  Rail ^  U (V) ^  I per unit (A) ^  I total (A) ^  P (W) ^
-| ESP32-C3 sensor nodes | 10 | 5V | 5 | 0.300 | 3.000 | 15.000 |
+| ESP32-C3 sensor nodes |  10 |  5.0 V |  5 |  0.300 |  3.000 |  15.000 |
-| ESP32-C3 central node | 1 | 5V | 5 | 0.300 | 0.300 | 1.500 |
+| ESP32-C3 central node |  1 |  5.0 V |  5 |  0.300 |  0.300 |  1.500 |
-| CAN transceiver MCP2551 | 10 | 5V | 5 | 0.010 | 0.100 | 0.500 |
+| CAN transceiver MCP2551 |  10 |  5.0 V |  5 |  0.010 |  0.100 |  0.500 |
-| LED strips WS2812B (2m, 120 LEDs each) | 3 | 12V | 12 | 7.200 | 21.600 | 259.200 |
+| LED strips WS2812B (2 m, 120 LEDs each) |  3 |  12 V |  12 |  7.200 |  21.600 |  259.200 |
-| Velostat pressure sensors | 15 | 3.3V | 3.3 | 0.001 | 0.015 | 0.050 |
+| Velostat pressure sensors |  15 |  3.3 V |  3.3 |  0.001 |  0.015 |  0.050 |
-| **Total** | | | | | | **276.250** |
+| **Total** | | | | | |  **276.250** |
-| **Total + 25% safety margin** | | | | | | **345.313** |
+| **Total + 25 % safety margin** | | | | | |  **345.313** |
 </table>
 </WRAP>
-The hardware implementation is realized through two dedicated PCB designs, corresponding to the distributed architecture of the Smart System: the Sensor Node PCB and the Central Node PCB.
+The hardware implementation is realized through two dedicated PCB designs: the Sensor Node PCB and the Central Node PCB.
-The Sensor Node PCB integrates all the components required for local sensing, processing, and communication. Each sensor node includes:
+**1. Sensor Node PCB**
-  *ESP32-C3 microcontroller (Wemos C3 Mini)
-  *MCP2551 CAN transceiver
-  *Velostat sensing circuit
-  *Power regulation (5V input)
-  *CAN bus interface (CANH / CANL)
-The Velostat sensing circuit is implemented using a voltage divider configuration, allowing pressure-induced resistance changes to be converted into measurable analog signals via the ESP32 ADC.
-As shown in Figure {{ref>fig:sensor_node_pcb}}, the PCB is designed to be embedded directly into the handrail structure. This mechanical integration ensures minimal visual impact, while maintaining robustness and protection against mechanical stress and vibration in a public transport environment.
+The Sensor Node PCB integrates all the components required for local sensing, processing, and communication. To convert physical pressure into data, the circuit utilizes a Velostat sensing interface in a voltage divider configuration. The detailed electrical connections are illustrated in the Sensor Node Schematic (Figure {{ref>fig:sensor_schematic}}).
-<figure fig:sensor_node_pcb>
+<WRAP centeralign>
-{{ :report:sensor_node_pcb.png?direct&400 |}}
+<figure fig:sensor_schematic>
-<caption>Sensor Node PCB</caption>
+{{ :report:EPS-velostat-schematicV3.svg?direct&600 |}}
+<caption>Sensor Node Schematic Diagram</caption>
 </figure>
+</WRAP>
+The node includes an ESP32-C3 Microcontroller (Wemos C3 Mini) and an MCP2551 CAN Transceiver. A 10kΩ potentiometer is included to allow manual calibration of the sensor's sensitivity range. As shown in Figure {{ref>fig:sensor_node_pcb}}, the PCB is designed to be embedded directly into the handrail structure for minimal visual impact and high mechanical robustness.
+<WRAP centeralign>
+<figure fig:sensor_node_pcb>
+{{ :report:sensor_node_pcb.png?direct&400 |}}
+<caption>Sensor Node PCB Layout</caption>
+</figure>
+</WRAP>
 Each Sensor Node PCB operates as an autonomous unit within the distributed system, transmitting processed sensor data through the CAN bus network to the Central Node.
-The Central Node PCB acts as the main processing and coordination unit of the system. It is responsible for aggregating data from all sensor nodes and generating the corresponding visual output.
+**2. Central Node PCB**
-This PCB integrates:
+The Central Node PCB acts as the main coordination unit. It is responsible for aggregating data from all sensor nodes and generating the corresponding visual output. The integration of the processing unit with the lighting infrastructure is detailed in the Central Node Schematic (Figure {{ref>fig:central_schematic}}).
-  *CAN network interface for multi-node data reception
+<WRAP centeralign>
-  *Data processing unit for system-level interpretation
+<figure fig:central_schematic>
-  *WS2812B LED strip control (single-wire digital output)
+{{ :report:eps-leds-schematicv3.svg?direct&600 |}}
+<caption>Central Node Schematic Diagram</caption>
+</figure>
+</WRAP>
-As shown in Figure {{ref>fig:central_node_pcb}}, the Central Node PCB is designed as the core element of the system architecture, consolidating communication, processing, and actuation within a single board.
+As shown in Figure {{ref>fig:central_node_pcb}}, this PCB consolidates communication and actuation. It features a dedicated WS2812B LED Control port with a 330Ω resistor (R1) in series to protect the data line and ensure signal integrity.
+<WRAP centeralign>
 <figure fig:central_node_pcb>
 {{ :report:central_node_pcb.png?direct&400 |}}
-<caption>Central Node PCB</caption>
+<caption>Central Node PCB Layout</caption>
 </figure>
+</WRAP>
+This board processes all incoming CAN messages and translates them into real-time visual feedback through the LED infrastructure, ensuring synchronization between multiple sensor inputs.
+**Technical Implementation Details**
+A critical aspect of the design is the voltage compatibility between the ESP32-C3 (3.3V) and the MCP2551 (5V). While the transceiver requires 5V to meet CAN standards, the ESP32-C3 GPIOs are not 5V tolerant. To address this, both schematics implement a voltage divider on the RX line, using a 1kΩ resistor in series and a 2kΩ resistor to ground. This scales the signal from the MCP2551 down to approximately 3.3V, ensuring safe operation. The TX line is driven directly at 3.3V, which the MCP2551 identifies as a valid logic "high."
+To ensure reliable data transmission within the electromagnetically noisy environment of a metro car, the system employs:
+  *Differential Signaling: Utilizing CAN High and CAN Low lines for high immunity to interference.
-This board is responsible for processing all incoming CAN messages and translating them into real-time visual feedback through the LED infrastructure distributed across the metro environment. Additionally, it ensures synchronization between multiple sensor inputs, enabling coherent system-wide lighting behavior.
+  *Bus Termination: A 120Ω resistor is placed across the CAN lines (as seen in the schematics) to match characteristic impedance and prevent signal reflections.
-== Software ==
+**Software**
 The software architecture of the Connect and Share project facilitates real-time interaction and asynchronous digital connection across two distinct modes of use.
@@ Line 303: / Line 292: @@
 Figure {{ref>fig:frontend_flowchart}} depicts the frontend flow of the Connect web interface. Starting from a QR code scan, the browser fetches and renders the website. The user is then presented with two interaction options: writing a message, which is transmitted to the backend, or reading a message, which triggers a random message fetch and displays it on screen.
-<WRAP center>
+<WRAP centeralign>
 <figure fig:frontend_flowchart>
 {{ :report:flowchart_web_1_.png?nolink&600 | Frontend flow}}
@@ Line 310: / Line 299: @@
 </WRAP>
-Figure {{ref>fig:backend_flowchart}} illustrates the backend flow. Incoming HTTP requests are routed based on method: GET requests retrieve a randomly selected stored message and return HTTP 200, while POST requests pass the submitted content through an ML/AI moderation check. Content flagged as harmful is rejected with HTTP 400; clean content is saved to the database and confirmed with HTTP 200.
+Figure {{ref>fig:backend_flowchart}} illustrates the backend flow. IIncoming Hypertext Transfer Protocol (HTTP) requests are routed based on method: GET requests retrieve a randomly selected stored message and return HTTP 200, while POST requests pass the submitted content through a Machine Learning (ML) / Artificial Intelligence (AI) moderation check. Content flagged as harmful is rejected with HTTP 400; clean content is saved to the database and confirmed with HTTP 200.
-<WRAP center>
+<WRAP centeralign>
 <figure fig:backend_flowchart>
 {{ :report:flowchart_web_2_.png?nolink&600 | Backend flow}}
@@ Line 321: / Line 310: @@
 Figure {{ref>fig:iot_flowchart}} shows the firmware logic running on the two ESP32-C3 nodes. The upper flow covers the sensor node: it enters deep sleep after setup and wakes on a touch interrupt, transmits the event over CAN bus, then resets and loops. The lower flow covers the actuator node: it similarly sleeps until a CAN bus data frame is received, drives the LED strip, and resets. Both nodes share the same interrupt-driven sleep cycle structure.
-<WRAP center>
+<WRAP centeralign>
 <figure fig:iot_flowchart>
 {{ :report:flowchart-iot.png?nolink&600 | Flowchart IoT}}
@@ Line 327: / Line 316: @@
 </figure>
 </WRAP>
-=== Packaging ===
+=== 7.4.3 Packaging ===
 Present and explain the:
 (//i//) initial packaging drafts;
@@ Line 393: / Line 382: @@
 (iii) usability tests according to the [[https://www.usability.gov/how-to-and-tools/methods/system-usability-scale.html|System Usability Scale]].
-==== Summary ====
+==== 7.6 Summary ====
 //Provide here the conclusions of this chapter and make the bridge to the next chapter.//