Tutorial: AnalysIR Reverse Engineering Tool for Infrared AC Signals

Summary

This tutorial delves into reverse engineering Toshiba AC signals, capturing 55 varied-length signals with a carrier frequency of 38 kHz. It emphasizes the importance of recording signals in ascending order and altering one feature at a time for clarity. The video demonstrates analyzing signal patterns, identifying the temperature field, and the significance of the checksum field. It also covers the process of identifying on/off signals and suggests using tools for further analysis, offering a demo for those interested.

Takeaways

• 🔍 The tutorial focuses on reverse engineering the temperature field of Toshiba AC signals.
• 📊 55 different Toshiba AC signals were captured, with varying lengths from 144 to 260 bits.
• 📈 The importance of arranging temperature fields in ascending order for easier reverse engineering is highlighted.
• 🔧 Changing only one feature at a time, such as temperature in one-degree increments, is recommended for systematic analysis.
• 🎚 The carrier frequency for these signals is 38 kilohertz, a key detail for understanding the signal structure.
• 🔑 CRC (Cyclic Redundancy Check) is identified as the last byte in the signal, indicating a checksum field.
• 🔄 The signal is repeated twice, with identical patterns, which is a common feature in protocols.
• 🌡 The temperature field is based on a base temperature and increments from there, often using the high nibble of a byte.
• 🔄 The tutorial demonstrates how to identify on/off fields by observing changes in specific bits.
• 📝 Recording button presses and temperature changes helps in correlating signal changes with user inputs.
• 👀 Hovering over hex values in the software provides a binary pop-up, aiding in reverse engineering.
• 📊 The bit order in the signal is most significant bit first, which is crucial for understanding the bit pattern.
• 🔧 The tutorial suggests using software tools to record and analyze signals, with the option to export data for further analysis.

Q & A

What is the primary focus of this video tutorial?

The primary focus of this video tutorial is reverse engineering the temperature field of a Toshiba AC signal.

How many Toshiba AC signals were recorded for this analysis?

A total of 55 Toshiba AC signals were recorded for this analysis.

What are the three different lengths of signals mentioned in the protocol?

The three different lengths of signals in the protocol are 144 bits, 260 bits, and 212 bits.

What is the carrier frequency for these Toshiba AC signals?

The carrier frequency for these Toshiba AC signals is 38 kilohertz.

What is the recommended approach when reverse engineering signals, according to the tutorial?

The recommended approach when reverse engineering signals is to change only one feature at a time, such as changing the temperature by one degree or the fan speed by one option at a time, to see the changes in the protocol more clearly.

Why is it important to have the temperature fields for each signal in ascending order?

Having the temperature fields in ascending order is important because it makes it easier to understand what you are trying to reverse-engineer and to observe the changes systematically.

What is identified as the last byte in each signal based on a previous tutorial?

The last byte in each signal is identified as the CRC (cyclic redundancy check) based on a previous tutorial.

How does the tutorial suggest identifying the on and off fields in the signals?

The tutorial suggests that the on and off fields can be identified by observing that on has a value of 1 and off has a value of 7 in the specific bits of the signal.

What is the significance of the high nibble in the temperature field?

The high nibble (top four bits) of the byte in the temperature field indicates the temperature value, with a base temperature and an increment for each degree change.

How does the tutorial recommend dealing with signals where bits span different bytes?

The tutorial recommends changing the bit order and experimenting a few times to ensure you get the correct pattern, especially since the bit order might be in LSB (least significant bit) or MSB (most significant bit) format depending on the protocol.