DisplayPort, HDMI and USB-C

DisplayPort, HDMI and USB-C are all commonly used interfaces in laptops. In addition to testing the interface-specific features, such as video and power delivery, testing e.g. HDCP compliance is crucial when ensuring the functionality of transmitter devices.

What to Test in Laptops

Video and Audio

On laptops, it is crucial to test the link stability and quality of the transmitted video stream. This can be done by capturing a reference frame that is compared to the transmitted video stream. These types of tests known as cyclic redundancy check (CRC) are time and cost-efficient ways of detecting link errors in the digital video stream. With laptops, featuring resolutions up to 4K, it is impossible to detect errors in the video stream with a bare human eye. Only testing with proper test tools can guarantee a stable and error-free video stream.

Corresponding tests can be run on audio where a certain reference frequency is tested. Unigraf’s test tools also enable the capturing and recording of compressed audio.

Besides built-in CRC tests, Unigraf’s UCD Console GUI also features a preview for the captured video and audio. The video preview shows detailed information about the captured video and audio including the resolution and color format.

Tutorial: DisplayPort CRC Video Stability Test with Unigraf’s UCD-340 and UCD Console

The screenshot below shows the preview for the captured video. Details of the captured video are shown in the bottom left corner.


Extended Display Identification Data (EDID) is a metadata format for display devices (e.g. monitors) to describe their capabilities to a video source (e.g. laptops). When testing laptops, it is crucial to ensure that the device will work with a variety of different kinds of monitors. Unigraf’s test tools come with a built-in EDID editor. You can use the EDID editor tool to simulate different monitors and make sure that your transmitter device works seamlessly with different monitors. With EDID Editor you can read the EDID from display devices and save it. You can then load the EDID into your UCD test tool and the test tool will act as the display device. You can build a comprehensive EDID library of different monitors. The EDID testing can be automated which enables fast and efficient testing of the interoperability between the laptop and different types of monitors.

Screenshot showing the EDID tool in UCD Console 

Link & HDCP

Having the capability to monitor and control link and HDCP encryption is a crucial part of testing any transmitter devices. Ungiraf’s test tools enable HDCP testing for both HDCP 1.4 and HDCP 2.3

Screenshot showing the link and HDCP controls

Connector Pins

Common manufacturing defects on laptops are poorly manufactured connector pins. A poorly soldered or grounded connector can result as a defected signal which can cause the video or audio to fail.

Some modern receiver devices have a high-quality receiver chip which can correct a defected signal. However, all receivers are different and even if your transmitter device works with a monitor it does not mean that it will work with all monitors. Therefore, it is crucial to use an actual test tool to test the DisplayPort, USB-C and HDMI connector.

Unigraf UCD-301, a 4K@60Hz capable HDMI and DisplayPort test tool, offers a unique solution for testing the connector pins. A built-in electrical test enables the testing of the connector.  The electrical test features ready-made tests for testing the signal continuity with the HDMI and DisplayPort connectors. Electrical tests can be automated for production line testing.

Unigraf USB-C test tool UCD-340 offers a unique solution for testing the USB-C connector pins. A built-in electrical test enables the testing of each connector pin. Thanks to a software-based cable flip, the electrical test enables testing of the USB-C connector with single cable insertion. In production, this saves valuable time as there is no need to insert the cable in both ways. The electrical test features ready-made tests for testing Vconn and Vbus voltage levels. All electrical tests can be automated for production line testing.

E-learning center: Testing connector pins

The screenshot below shows the built-in electrical test set in UCD Console GUI

USB-C Power Delivery

As USB-C laptops can act as a power source (charger) and power sink (device being charged), there is a need to test that the device works correctly on all USB-C Power Delivery roles. Only with the proper test tool, you can test the different USB-C Power Delivery functions. Different e.g. chargers and devices have different capabilities to receive and deliver power. Up to 100W of power can be delivered with different voltage and current configurations. With proper test tools, you can load the smartphone with different power delivery configurations.

The screenshot shows the control panel for different DP Alt Mode and USB-C Power Delivery roles and functionalities.

Compliance Testing

In order to obtain the DisplayPort certification for laptops with DisplayPort connector, a proper compliance testing needs to be performed with certified compliance test tools. Also, laptops with USB-C DisplayPort Alternate Mode capability need to be tested for DisplayPort compliance. As there are hundreds of manufacturers making DisplayPort devices, compliance testing according to VESA and DCP standards is the only way to ensure interoperability between different DisplayPort devices available on the market.

More information: Compliance Testing

Link Layer CTS Testing

The core of the DisplayPort compliance testing is the Link Layer Compliance Testing. The Link Layer compliance testing is always done according to the latest DisplayPort specification. In the link layer compliance testing the link between the transmitter and receiver devices is analyzed and tested according to the specifications. Also, all of the different timings (e.g. 4K@60Hz) that can be transmitted under the specifications are tested.

Unigraf’s DP 2.0 Test Tool UCD-500

Unigraf’s DP 1.4 Test Tool UCD-400

HDCP 2.3 CTS Testing

DisplayPort devices employ HDCP encryption to protect the digital content. In 2018 VESA announced that it requires HDCP testing as part of the DP testing requirement for certification. If a DP Source or Sink supports HDCP (as reported in the product CDF) it shall be tested as part of the certification requirements for obtaining the DP Logo. (Source: VESA). The latest HDCP specification is the HDCP 2.3 which is used in smartphones that support USB-C DP Alt Mode.


Test Solutions for Testing Laptops

Ungiraf UCD Series Test Tools

UCD-500 • UHBR Capable State of the Art Test Tool

UCD-500 is a DisplayPort™ 2.0 Video Generator and Analyzer unit for testing DisplayPort Sinks and Sources up to 8K@60Hz and 16K@60 Hz (with DSC) video modes with UHBR 20 Max Bit Rate Capability. 10 Gb rate max capability for DP 2.0 connectors, due to current DP 2.0 implementation, and 20 Gb rate max capability for USB-C connectors. UCD-500 offers support for Panel Replay, Adaptive Sync, DSC, FEC, and LTTPR.

More information: UCD-500

UCD-424 • HBR3 Capable Video Transmitter and Receiver

UCD-424 is an interface test unit for verifying DisplayPort™ Alternate mode over USB-C™ up to 8K@30 Hz and 4K@120 Hz video modes.  UCD-424 supports both DisplayPort 1.4a Link Layer and HDCP 2.3 CTS testing. UCD-424 features DP 1.4 / HBR3 input and output in one unit. Further, it features USB-C v1.3 input and output with Power Delivery 3.0.

More information: UCD-424

UCD-422 • HDMI 2.1 Test Tool

UCD-422 is a HDMI 2.1 (FRL) Test Equipment supporting resolutions up to 10K@30Hz and 8K@60Hz. UCD-422 also supports enhanced gaming features in Variable Refresh Rate (VRR) and Auto Low Latency Mode (ALLM)

More information: UCD-422

UCD-400 • 8K Capable DisplayPort Test Tool

UCD-400 is a DP 1.4 / HBR3 capable video generator and analyzer. UCD-400 enables testing of DisplayPort receivers up to 8K@30Hz or 4K@120Hz. It has support for DisplayPort 1.4a Link Layer and HDCP 2.3 compliance testing. UCD-400 also supports DSC, FEC, MST (4 streams), and LTTPR.

More information: UCD-400

UCD-340 • 4K USB-C DP Alt Mode Video Analyzer and Generator

Unigraf’s UCD-340 is a fully-featured R&D Debug Test Tool designed for engineers developing new products in R&D laboratory environment. It supports transmitting and receiving video up to 4K@60Hz. UCD-340 is the only DCP Approved HDCP 2.3 CTS Test Tool for testing USB-C DP Alt Mode receivers and transmitters.

More information: UCD-340

UCD-323 • 4K HDMI & DP Video Analyzer and Generator

UCD-323 is a 4K@60Hz capable HDMI 2.0 and DisplayPort (HBR2) video analyzer and generator. With UCD-323 you can test both HDMI and DisplayPort transmitters (e.g. laptops) and receivers (e.g. monitors).

More information: UCD-323

UCD-301 • 4K HDMI & DP Video Analyzer with Electrical Test

UCD-301 is a 4K@60Hz capable test tool for testing HDMI and DisplayPort (HBR2) transmitters (e.g. laptops). UCD-301 features Ungraf’s unique electrical test that can be used to test that the HDMI or DP connector is soldered and grounded properly. Manufacturing defects in the connector can cause e.g. the video or audio stream to fail. Electrical Test makes UCD-301 an optimal test tool for production line testing.

More information: UCD-301


Test Tool for Testing Laptops

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