44 lines
1.9 KiB
Markdown
44 lines
1.9 KiB
Markdown
# HDMI Tester Project
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## Overview
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This project aims to create a handheld HDMI tester for console repair technicians. It features two modes:
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- **Intake Mode**: Simple Pass/Fail with diagnostic suggestions.
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- **Tech Mode**: Detailed diode mode readings for all 19 HDMI pins.
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## Hardware Recommendations
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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.
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### 1. Microcontroller: ESP32 or Raspberry Pi Pico
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- **ESP32**: Integrated Wi-Fi/BT (good for future logging), multiple ADCs.
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- **RP2040 (Pico)**: Great documentation, dual-core, very affordable, stable ADCs.
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- **Recommendation**: **Raspberry Pi Pico** for its simplicity and 3.3V logic which is safer for HDMI lines.
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### 2. Multiplexers (Mux)
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Since the Pico doesn't have 19 ADC pins, we need multiplexers to switch between the HDMI pins.
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- **CD74HC4067**: 16-channel analog multiplexer. We would need two of these to cover all 19 pins + GND checks.
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### 3. Display
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- **0.96" or 1.3" OLED (SSD1306/SH1106)**: Simple I2C connection, low power.
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### 4. Input
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- **Rotary Encoder with Push Button**: Ideal for switching between Intake and Tech modes.
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### 5. HDMI Breakout
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- A standard HDMI male/female breakout board to interface the pins to the Mux.
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## Theory of Operation (Diode Mode)
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1. Connect the Red probe (GND in Diode Mode) to the HDMI ground.
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2. Connect the Black probe (Signal) to the data line.
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3. The tester will simulate this by:
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- Setting a pin to 3.3V through a precision resistor (e.g., 10k ohm).
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- Measuring the voltage at the junction with the HDMI pin via the Mux.
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- A healthy ESD diode or IC junction will show a specific voltage drop (typically 0.3V - 0.7V).
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- Open circuit = ~3.3V.
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- Short to GND = 0V.
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## Next Steps
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1. Define the Pinout mapping.
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2. Create the software structure (C++ or MicroPython).
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3. Implement the measurement logic.
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