AV.link

AV.link, also known under the trade names nexTViewLink, SmartLink, Q-Link, EasyLink, etc., is a protocol to carry control information between audio-visual devices connected via the SCART (EIA Multiport) connector.

It is standardised as CENELEC EN 50157-1.

The Consumer Electronics Control (CEC) communication channel in HDMI and PDMI is based on AV.link.

Electrical characteristics

AV.Link uses a single wire in an open collector configuration. It is passively pulled up to 3 or 3.3 V, and may be pulled down by any device on the bus. Total bus capacitance is a maximum of 7300 pF (ten devices at 100 pF each, plus nine cables at 700 pF), and signal transitions are correspondingly slow: 333 bit/s, with 50 μs fall time and 250 μs rise time.

Each bit transferred begins with a falling edge. The duration of the low period determines the value.

Data bits are 2.4±0.35 ms long, with 1 bits having a low period of 0.6±0.2 ms, and 0 bits having a low period of 1.5±0.2 ms. Receivers observe the data line at 1.05±0.2 ms after the falling edge to determine the bit's value.