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6.1 Overview

The transport layer maps the conversion samples to non-scrambled octets. JESD204 provides several options for this mapping:

  • A single converter to a single-lane link
  • Multiple converters in the same device to a single-lane link
  • A single converter to a multi-lane link
  • Multiple converters in the same device to a multi-lane link

In addition, it is possible to combine the interfaces of multiple converter devices on a multipoint link. However, this is not a special mapping case. The transport layer mapping applies only to the samples of a single converter device, i.e., transmitted over a single link.

A set of samples and/or partial samples is grouped into a frame of (F) octets. In many applications, the frame duration will be equal to the sampling interval. However, JESD204 allows more than one sample per converter to be transmitted per frame duration. The number (S) of samples per converter per frame duration shall always be an integer. This is necessary in order to minimize cross-talk between the SERDES circuits and sensitive analog parts. Each sample is transmitted as a group of (N) bits, consisting of (N) data bits, optional control bits and optional tail bits. . Additional tail bits at the end of the frame may be necessary to fill a whole number of octets per lane per frame cycle.

The user data mapping is parameterized according to the descriptions in the next subclauses. The limit for these parameters is only set by the needs of a particular converter device.