ASA Motion Link Delivers Camera and Sensor Connectivity

The Automotive Serdes Alliance (ASA) is a non-profit alliance established in 2019 that encourages the standardization of asymmetric SerDes technologies. The ASA Motion Link (ASA-ML) v2.x standard defines an asymmetric link with a downlink speed up to 64 Gb/s. This fits well with sensors like cameras, which send lots of data to the host but there’s minimal communication from host to sensor. The latter tends to be configuration information running at a much lower speed.

I talked with Chris May, an Applications Engineer at Microchip Technology, about the company’s implementation of ASA Motion Link and how it operates (watch the video above).

Key Features of ASA Motion Link

ASA Motion Link, which targets automotive and robotic applications, defines the physical, data-link, and transport layers of the interface. A typical use case is a surround-view camera system (Fig. 1). The standard defines 15-m coaxial and 10-m shielded differential pair (SDP) distance that is ideal for these applications. The system is designed to support up to four inline connectors.

The maximum download data rate is 16 Gb/s with an uplink rate that’s at least 100 Mb/s. Similar to time-sensitive networking (TSN), ASA Motion Link provides a deterministic delivery framework. Power can also be provided, removing an additional connection to an ASA Motion Link node such as a camera. Systems employ PAM2/NRZ or PAM4 signaling.

The v1.01 standard defined Application Stream Encapsulation Protocol (ASEPs) for Video, I2C, and Ethernet. The standard defines a link layer security (ASAsec) framework that includes a key exchange mechanism. It also specifies EMC immunity and EMI emission profiles.

ASA Motion Link v1.1 ups the top downlink line rate to 64 Gb/s. Furthermore, it adds ASEPs for protocols such as I2S, GPIO, embedded DP, SPI, and HDMI. This in turn simplifies a node’s interface to other devices. ASA Motion Link v2.x added Asymmetric Ethernet (ASA-MLE) support.

Microchip’s ASA Motion Link Chips

Microchip’s ASA Motion Link offering includes the VS775S single-port SerDes and VS776 multi-port hub (Fig. 2). Supporting ASA-ML v2.1, they’re ISO 26262 ASIL B certified and AEC-Q100 Grade 2 qualified.

The VS775S can be configured as a serializer or a deserializer. The serializer would be part of a device like a camera, while the latter would be a host connection. It includes on-chip non-volatile memory, allowing for external EEPROM-less camera configuration.