DisplayPort bus demands different tests
By Martin Rowe, Senior Technical Editor -- Test & Measurement World, 6/1/2009 2:00:00 AM
DisplayPort, the serial bus that sends digital video to TVs and monitor screens, needs testing like any other high-speed bus. Timing jitter can affect the BER (bit-error rate) of the bus and produce errors that result in poor video or audio. DisplayPort's architecture, which uses a multilane, unidirectional main link (figure) for transferring video and audio, differs from other buses that use bidirectional links. Thus, you can't run loopback tests.
 A DisplayPort link consists of a one, two, or four-lane unidirectional main link and a bidirectional auxiliary channel for control and status monitoring. |
Instead, you must rely on a DisplayPort receiver, called a sink device, to count its own bit errors. A counter in the device counts errors, and you poll the counter through a low-speed bidirectional port called the aux (auxiliary) channel.
When testing a sink device, you need to inject a PRBS (pseudorandom bit sequence) data stream and add jitter to the stream. Then, you can read the registers of the bit counter. To gain access to the aux channel and to the main link, you need an aux-channel controller board. The board contains connectors to which you can connect a signal from a BER tester or arbitrary waveform generator. Because cables and connectors add jitter and loss to signals, you must compensate for those losses through de-embedding.
To learn more about DisplayPort testing, see "DisplayPort adds testing twists" by Steve Sekel of Synthesys Research.
No related content found.
- 0 rated items found.
Datasheets.com Electronic Parts & Inventory Search
185 million searchable parts
- Part Number
- Description
- Inventory
- Products
- Manufacturers
View All Webcasts
