A dual-purpose hardware/firmware system that bridges a **Toyota 5S-FE engine ECU** to a carputer network over WiFi/UDP, while also providing relay-driver outputs for body electronics control.

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## What It Does

- **Reads engine sensors** — MAP, coolant temp, throttle position, vehicle speed, RPM, fuel level, oil pressure

- **Reads diagnostic trouble codes (DTC)** — via the check-engine light blink pattern

- **Monitors door/status switches** — driver, passenger, trunk, hood

- **Streams all data over WiFi** — JSON-formatted UDP packets to a head unit or carputer

- **Drives body relays** — door locks, windows, HVAC, fans, interior lights (via 2× ULN2003A)

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## Hardware Design

| Aspect | Detail |

|--------|--------|

| **Board size** | 160 × 120 mm, 2-layer FR-4 |

| **Assembly** | Through-hole (THT) — axial resistors, DIP ICs, WAGO connectors |

| **MCU** | 2× ESP32 DevKit V1 (sensor + body controller) |

| **Power** | 12V automotive → external DC-DC buck converter → 3.3V rail |

| **Relay drivers** | 2× ULN2003A (DIP-16) — 7 darlington pairs each |

| **Connectors** | 3× WAGO 8-way for vehicle harness, 2-way WAGO for power |

### ECU Interface

- **6 voltage dividers** (5.6K + 10K) scale 0–5V ECU signals to 0–3.3V for ESP32 ADC

- **2 sender pullups** (120Ω to 3.3V) for fuel level and oil pressure

- **4 digital inputs** with 10K series resistors + internal pullups for door switches

- **DTC read circuit** — 2× 2N2222 transistors (TE1/TE2) controlled via GPIO

### Body Control Outputs

| ULN2003A #1 | ULN2003A #2 |

|-------------|-------------|

| Door lock | HVAC on/off |

| Window up | AC compressor |

| Window down | Remote start |

| Interior light | Fan speed 2 |

| Door chime | Fan speed 1 |