How FLIR Lepton Video and Command Interfacing Works

Integrating the FLIR Lepton micro thermal camera module requires developers to consider both thermal video output and camera command and control. Depending on the development environment, Lepton can be integrated with processor-based platforms such as Raspberry Pi or evaluated on Windows using a compatible interface board such as PureThermal.

In this episode of Thermal Integration Made Easy, original equipment manufacturer (OEM) engineers and developers learn the fundamentals of Lepton video and command interfacing, including automatic gain control (AGC), radiometric temperature data, telemetry, Serial Peripheral Interface (SPI) video, Inter-Integrated Circuit (I2C) communication, the Lepton software development kit (SDK), and development options for Raspberry Pi and Windows.

Key Takeaways

How do developers interface with the FLIR Lepton thermal camera module?

Lepton has a specific electrical interface, so developers can integrate the module with a processor-based platform such as Raspberry Pi or use a PureThermal interface board for development and testing on Windows.

How does FLIR Lepton output thermal video?

Lepton provides a single video output from the camera. Developers need to determine where image processing such as AGC will be performed based on whether the application requires thermal contrast, temperature data, or both.

When should AGC be performed on the Lepton camera? 

For designs that do not require radiometry and only need to display contrast within the scene, AGC can be performed on the camera using the post-AGC red-green-blue 8-bit-per-channel (RGB888) output.

What if an application needs both temperature data and high-contrast thermal video?

Because only one video output is available from the camera, applications requiring both temperature data and high-contrast video need AGC to be performed by the integrator’s processing platform.

How are commands sent to FLIR Lepton?

The Lepton SDK is used for camera command and control over I2C. The SDK contains the I2C communication protocol and handles functions including command construction and byte packing.

How can developers access Lepton telemetry data?

Telemetry provides access to camera parameter values. Parameters such as the focal plane array temperature (TFPA) of the Lepton sensor can be acquired from the SDK over I2C and are also viewable through telemetry in the SPI video.

When should commands be sent to the Lepton camera?

Lepton can be programmed so commands are not required for specific settings, but this approach requires specialized hardware and processing and is rarely implemented. For most integrations, commands are sent to the camera after boot-up when the system is ready for use.

What development platforms can be used with FLIR Lepton?

Raspberry Pi is one option for Linux or processor-based implementations. For Windows-based testing, Lepton can be paired with a PureThermal board and the Lepton User App, with the board providing standard USB output for USB Video Class (UVC) streaming.

Products & Technology Featured

FLIR Lepton Micro Thermal Camera Module

FLIR Lepton is a compact longwave infrared (LWIR) thermal camera module designed for OEM integration. Developers can access thermal video, camera parameters, telemetry, and command and control functionality when integrating Lepton into processor-based systems and other thermal imaging applications.

Lepton SDK and Lepton User App

The Lepton SDK provides camera command and control over I2C, including the communication protocol, command construction, and byte packing. The Lepton User App provides a standard application for Windows-based development and testing when Lepton is paired with a PureThermal board.

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Engineering Documents

• Lepton Engineering Datasheet
• Lepton 3 Software Interface Description Document (IDD) Rev 303

Brochures

• Lepton Series Datasheet
• Lepton FS1 Datasheet
• Lepton Breakout Board V2.0 Datasheet

Certifications

• Lepton Thermal Core - Declaration of Compliance Rev 210
• Lepton Breakout Board - Declaration of Compliance Rev 120
• Lepton California Proposition 65 Declaration Rev 100
• Lepton RoHS Certificate of Compliance Rev 190