# HDMI Tester Project

## Overview
This project aims to create a handheld HDMI tester for console repair technicians. It features two modes:
- **Intake Mode**: Simple Pass/Fail with diagnostic suggestions.
- **Tech Mode**: Detailed diode mode readings for all 19 HDMI pins.

## Hardware Recommendations

To measure diode mode (voltage drop across a diode junction), we need a microcontroller with an ADC and the ability to source a small constant current or use a pull-up resistor.

### 1. Microcontroller: ESP32 (S3 or DevKitV1)
- **ESP32**: Integrated Wi-Fi/BT is essential for the server-side logging feature. It has multiple ADCs and enough GPIOs to drive the multiplexers.
- **RP2040 (Pico W)**: Also an option, but ESP32 has better community support for async HTTP clients.
- **Recommendation**: **ESP32-S3** for its high number of GPIOs and built-in Wi-Fi.

### 2. Multiplexers (Mux)
Since the Pico doesn't have 19 ADC pins, we need multiplexers to switch between the HDMI pins.
- **CD74HC4067**: 16-channel analog multiplexer. We would need two of these to cover all 19 pins + GND checks.

### 3. Display
- **0.96" or 1.3" OLED (SSD1306/SH1106)**: Simple I2C connection, low power.

### 4. Input
- **Rotary Encoder with Push Button**: Ideal for switching between Intake and Tech modes.

### 5. HDMI Breakout
- A standard HDMI male/female breakout board to interface the pins to the Mux.

## Theory of Operation (Diode Mode)
1. Connect the Red probe (GND in Diode Mode) to the HDMI ground.
2. Connect the Black probe (Signal) to the data line.
3. The tester will simulate this by:
   - Setting a pin to 3.3V through a precision resistor (e.g., 10k ohm).
   - Measuring the voltage at the junction with the HDMI pin via the Mux.
   - A healthy ESD diode or IC junction will show a specific voltage drop (typically 0.3V - 0.7V).
   - Open circuit = ~3.3V.
   - Short to GND = 0V.

## Next Steps
1. Define the Pinout mapping.
2. Create the software structure (C++ / Arduino with ESP32 WiFi libraries).
3. Implement the measurement logic.