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Decoding Infrared Remote Control Signals with IR Decoder ICs

Decoding Infrared Remote Control Signals with IR Decoder ICs

Infrared (IR) remote controls are everywhere – TVs, audio equipment, air conditioners all use IR remotes to control various functions. At the heart of these remotes and devices is the ir remote decoder ic. These chips take the modulated IR signal from the remote, decode it, and output the control commands to the rest of the appliance circuitry. In this article, we’ll look at common IR decoder ICs and how to use them in your next embedded project.

Common IR Decoder ICs

There are many decoder ICs to choose from. Here are some popular options:

TSOPXX38 Series

These are some of the most commonly used and inexpensive IR receiver modules. Key features:

  • TSOP17XX – receives IR up to 1MHz
  • TSOP48XX – receives IR up to 4MHz
  • Output is active low
  • Comes in convenient epoxy molded package

Vishay TSOP312XX Series

Higher performance and features than TSOPXX38 series:

  • Receives signals up to 4MHz
  • Higher sensitivity and ambient light immunity
  • Comes in leaded package for through-hole mounting

Vishay TSSP4038

Specialty IR receiver IC:

  • Receives signals up to 40MHz
  • High speed IR reception for RC hobby applications
  • Surface mount package
ICMax FrequencyOutputPackage
TSOP17381MHzActive LowEpoxy molded
TSOP48384MHzActive LowEpoxy molded
TSOP312364MHzActive LowLeaded
TSSP403840MHzActive LowSMD

Table: Comparison of common IR decoder ICs

Using an IR Decoder IC

Using an IR decoder IC is straightforward:

  1. Connect power and ground
  2. Add filtering capacitors for clean power
  3. Connect output pin to microcontroller input
  4. Add IR receiver LED aligned with line of sight
  5. Decode output signal transitions to recover control codes

Many modules like TSOPXX38 come pre-assembled with the IR receiver and capacitor filter. Otherwise, an IR photodiode or phototransistor is used. The output pin switches low when IR modulated light is detected. A microcontroller detects the pulse lengths and gaps to recover the underlying control signal.

With high speed decoders like TSSP4038, additional amplification may be needed before feeding the output to a microcontroller.

Example Projects

Some examples of how IR decoder ICs can be used:

  • IR remote spy – Log and analyze IR signals
  • Universal remote – Record and playback IR commands
  • IR to WiFi bridge – Control appliances over a network
  • IoT automation – Control appliances with smartphone apps

The wide variety of inexpensive decoder ICs make them easy to integrate into IoT and automation projects. With just a microcontroller and few other components, powerful IR remotes can be created.

Frequently Asked Questions

What is the maximum range for IR remotes?

Most IR remotes have a range of about 20-30 feet, depending on conditions. Range can vary based on transmitter power, receiver sensitivity, ambient light conditions, and alignment.

Can IR signals pass through walls?

No, IR signals cannot penetrate solid objects like walls. IR remotes require line-of-sight to function properly.

What carrier frequencies are typically used?

Most IR remotes modulate the signal onto a carrier between 30-60kHz. Higher frequencies up to 455kHz may also be used.

Is IR technology being replaced by RF?

In some applications, yes. RF remotes using Bluetooth and WiFi allow control without line-of-sight. However, simple IR remotes are still inexpensive and ubiquitous.

Can IR remotes interfere with each other?

Yes, many IR remotes use similar carrier frequencies. Physical blocking of signals is required to isolate remotes.