Begining of project

HARDWARE.md

@@ -0,0 +1,43 @@
+# 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 or Raspberry Pi Pico
+- **ESP32**: Integrated Wi-Fi/BT (good for future logging), multiple ADCs.
+- **RP2040 (Pico)**: Great documentation, dual-core, very affordable, stable ADCs.
+- **Recommendation**: **Raspberry Pi Pico** for its simplicity and 3.3V logic which is safer for HDMI lines.
+
+### 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++ or MicroPython).
+3. Implement the measurement logic.