System_Architecture.md

System Architecture: ESP-NOW Joystick Transmitter

This document delineates the logical construction of the wireless joystick remote controller, designed specifically to operate completely independently of the robotic platform it governs.

High-Level Topology

The system operates across three core domains: analog peripheral sampling, signal normalization, and wireless payload compilation.

graph TD
    classDef hardware fill:#0b1d30,stroke:#2a5275,stroke-width:2px,color:#ffffff
    classDef software fill:#16322b,stroke:#2a5f51,stroke-width:2px,color:#ffffff
    classDef process fill:#2d4263,stroke:#1e3c50,stroke-width:2px,color:#d8e2dc

    subgraph Sensory Environment
        POT_Y[Y-Axis Potentiometer]:::hardware -->|Analog voltage| ADC_Y[ESP32 ADC1 CH7]:::software
        POT_X[X-Axis Potentiometer]:::hardware -->|Analog voltage| ADC_X[ESP32 ADC1 CH6]:::software
        BTN[Tactile Switch]:::hardware --> INT[Interrupt Pullup]:::software
    end

    subgraph Filtration & Normalization
        ADC_Y --> OVS[Multi-Sampling Average]:::process
        ADC_X --> OVS
        OVS --> EMA[EMA Noise Filter]:::process
        EMA --> CALC[Deadzone Removal]:::process
    end

    subgraph Synthesis & Transmission
        CALC -->|Y -1 to +1| SCL_Y[Scale to MAX_TARGET_ANGLE]:::process
        CALC -->|X -1 to +1| SCL_X[Scale to MAX_STEERING]:::process
        SCL_Y --> PKT[JoystickPacket Struct]:::software
        SCL_X --> PKT
        INT --> PKT
        PKT --> TX[ESP-NOW Protocol Stack]:::software
        TX -->|Hardware MAC Vector| RADIO((WiFi Radio)):::hardware
    end

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1. Subsystem Descriptions

Analog Acquisition (ADC1 Only)

The ESP32 platform restricts access to ADC2 structures the moment the RF radio engages. Therefore, the architectural hardware interface is strictly limited to ADC1 pins (GPIO 34, GPIO 35).

• The 12-bit ADC generates inputs ranging linearly between 0 and 4095.
• Mechanical resting center discrepancies observed amongst cheap physical potentiometers are eliminated via an initial 64-sample resting state integration executed strictly during the boot procedure.

Signal Processing

Voltages harvested from physical manipulation undergo significant mathematical normalization before broadcast.

1. Oversampling: 4 distinct sequential analog queries are aggregated and averaged to aggressively negate immediate instantaneous micro-spikes originating within the electrical rails.
2. Exponential Smoothing (EMA): Applied dynamically to generate a mathematically clean transitional curve eliminating rigid mechanical jitter outputted by the potentiometers.
3. Deadzone Exclusion: Fractional signal discrepancies occupying the centralized logical region near 0.0 mathematically default to zero, preventing aggressive robotic drifting when thumbs are removed securely from the stick.

Target Constraints Integration

Previously, the Joystick forwarded raw -1.0 to 1.0 scalar factors, assuming the robot constrained physical behavior rules. In current iterations:

• The joystick asserts architectural dominance over scaling logic.
• Input vectors are mathematically expanded explicitly out to arbitrary constants, specifically matching the definitions declared in $MAX_TARGET_ANGLE (5.0 degrees) and $MAX_STEERING (1.0 scalar multiplier).

Asynchronous Broadcasting

Transmissions follow a draconian temporal throttling executing exclusively at precisely 50 Hz ($dt = 20ms$).

• Operating via the ESPNOW architectural standard sidesteps the debilitating 3-way handshake delays typically required to initiate TCP/IP connections.
• Packets act directly as User Datagram constraints broadcast cleanly towards the exact physical Receiver MAC address, drastically curbing transmission and processing latencies.

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2. RQT Control Structure Graph