# WijiBoard Wiring Diagram

This document outlines the hardware connections for the WijiBoard. 

## Hardware Components
- **Microcontroller**: Tenstar Robot ESP32-C3 Super Mini
- **Motors**: 2× 28BYJ-48 (5V Stepper Motors)
- **Motor Drivers**: 2× ULN2003 Driver Boards
- **Power System**: 
  - 4S LiPo Battery
  - XH-M609 Battery Low-Voltage Disconnect Module
  - 2× Buck Regulators (step-down converters tuned to 5V)

---

## Power Connections
The system is powered by a 4S LiPo battery. To protect the battery from over-discharge, it is connected to an **XH-M609** module. The output of the XH-M609 is split into two separate **Buck Regulators**, both tuned to output 5V.

1. **Buck Regulator 1 (MCU Power)**: Dedicated to powering the ESP32-C3 Super Mini.
2. **Buck Regulator 2 (Motor Power)**: Dedicated to powering both ULN2003 driver boards to prevent voltage drops or electrical noise from affecting the MCU.

> [!IMPORTANT]
> **Common Ground**: You MUST connect the Ground (GND) from the ESP32 to the Ground (GND) of the ULN2003 drivers. Even though they have separate 5V power supplies, they need a common ground reference for the GPIO logic signals to work correctly.

| Component | Connection | Destination |
| :--- | :--- | :--- |
| **4S LiPo** | `BAT+` / `BAT-` | XH-M609 `VIN+` / `VIN-` |
| **XH-M609** | `VOUT+` / `VOUT-` | Split to **IN+** and **IN-** on both Buck Regulators |
| **Buck 1 (MCU)** | `OUT+ (5V)` | ESP32-C3 Super Mini `5V` (used as power input) |
| **Buck 1 (MCU)** | `OUT- (GND)` | ESP32-C3 Super Mini `GND` |
| **Buck 2 (Motors)**| `OUT+ (5V)` | ULN2003 (M1) `+ / 5V` and ULN2003 (M2) `+ / 5V` |
| **Buck 2 (Motors)**| `OUT- (GND)` | ULN2003 (M1) `- / GND` and ULN2003 (M2) `- / GND` |
| **ESP32-C3 Super Mini** | `GND` | Tie to the motor ground network (Common Ground) |

---

## Motor 1 (Right Motor) Logic
**Physical Location**: Right side (pivot at +12.9mm)

| ESP32-C3 Super Mini Pin | ULN2003 (Motor 1) Pin |
| :--- | :--- |
| **GPIO 0** | `IN1` |
| **GPIO 1** | `IN2` |
| **GPIO 3** | `IN3` |
| **GPIO 4** | `IN4` |

---

## Motor 2 (Left Motor) Logic
**Physical Location**: Left side (pivot at -12.9mm)

| ESP32-C3 Super Mini Pin | ULN2003 (Motor 2) Pin |
| :--- | :--- |
| **GPIO 5** | `IN1` |
| **GPIO 6** | `IN2` |
| **GPIO 7** | `IN3` |
| **GPIO 10** | `IN4` |

---

## Stepper to Driver Connections
Simply plug the white 5-pin JST connectors from the 28BYJ-48 motors into the corresponding white sockets on their respective ULN2003 driver boards. The connector is keyed and only fits one way.

---

## Alternative Board Pinouts

The project supports multiple ESP32 variants. The main tables above show the default ESP32-C3 Super Mini. If you are using a different board, follow these logic connections:

### ESP32-S3 (e.g. DevKitC)
| Motor | IN1 | IN2 | IN3 | IN4 |
| :--- | :--- | :--- | :--- | :--- |
| **Motor 1 (Right)** | GPIO 4 | GPIO 5 | GPIO 6 | GPIO 7 |
| **Motor 2 (Left)** | GPIO 15 | GPIO 16 | GPIO 17 | GPIO 18 |

### ESP32-WROOM (e.g. NodeMCU / DevKit V1)
| Motor | IN1 | IN2 | IN3 | IN4 |
| :--- | :--- | :--- | :--- | :--- |
| **Motor 1 (Right)** | GPIO 13 | GPIO 14 | GPIO 27 | GPIO 26 |
| **Motor 2 (Left)** | GPIO 25 | GPIO 33 | GPIO 32 | GPIO 23 |

## Schematic Overview

```mermaid
flowchart LR
    subgraph Power Delivery
        BATT[4S LiPo Battery] -->|14.8V| XHM609[XH-M609 Protector]
        XHM609 -->|14.8V| BUCK1[Buck Regulator 1]
        XHM609 -->|14.8V| BUCK2[Buck Regulator 2]
    end

    BUCK1 -->|5V Power| ESP[ESP32-C3 Super Mini]
    BUCK2 -->|5V Power| M1_Driver[ULN2003 M1]
    BUCK2 -->|5V Power| M2_Driver[ULN2003 M2]
    
    %% Common Ground
    ESP -. Common Ground .- M1_Driver
    ESP -. Common Ground .- M2_Driver
    
    %% Logic Signals
    ESP -- Pins 0,1,3,4 --> M1_Driver
    ESP -- Pins 5,6,7,10 --> M2_Driver
    
    %% Motors
    M1_Driver == 5-wire cable ==> M1[Motor 1 - Right]
    M2_Driver == 5-wire cable ==> M2[Motor 2 - Left]
```