NXP Semiconductors PXN2020, Reference Manual, Page: 774 / 1376

Media Local Bus (MLB)
PXN20 Microcontroller Reference Manual, Rev. 1
27-2 Freescale Semiconductor
27.1.2 Features
• 3-pin MediaLB interface supported
• Support for as many as 16 logical channels and as many as 31 physical channels running at a
maximum speed of 1024Fs
• Programmable MediaLB clock frequency
— 256 Fs = 12.3 megabits per second @ Fs = 48 kHz
— 512 Fs = 24.6 megabits per second @ Fs = 48 kHz
• Supports all MOST data types:
— Control messages
— Packet messages (asynchronous)
— Streaming data (synchronous)
— Isochronous data (when supported by MLB master)
• Supports DMA style backend user interface
• Transmission of commands and data and reception of receive status when functioning as the
transmitting device associated with a logical channel address
• Reception of commands and data and transmission as receive status responses when functioning
as the receiving device associated with a logical channel address
• MLB lock detection
• System channel command handling
• System bus master supporting direct memory access between the MLB and system RAM
• Local channel buffer memory of 2K quadlets shared between all the logical channels
27.1.3 Overview
The MLB module implements the physical layer and link layer of the Media Local Bus specification,
interfacing to the MLB controller. The MLB implements the 3-pin MLB mode and can run at speeds as
fast as 1024Fs. It does not implement MLB controller functionality.
All MLB devices support a set of physical channels for sending data over the MLB. Each physical channel
is 4 bytes in length (quadlet) and grouped into logical channels with one or more physical channels
allocated to each logical channel. These logical channels can be any combination of channel type
(synchronous, asynchronous, control, or isochronous) and direction (transmit or receive).
The MLB provides support for as many as 16 logical channels and as many as 31 physical channels with
a maximum of 124 bytes of data per frame. Each logical channel is referenced using an unique channel
address and represents a unidirectional data path between a MLB device transmitting the data and the MLB
device(s) receiving the data.
Once per MOST network frame, the MLB controller generates a unique frame sync pattern. This pattern
defines the frame and channel boundaries of the signal information and data lines.
The MLB controller initiates all communication over the MLB by sending out the logical channel address
on the signal information line for each physical channel. This logical address indicates to the appropriate