DS90UH949-Q1 Datasheet, PDF (36/87 Pages) Texas Instruments – 1080p HDMI to FPD-Link III Bridge Serializer with HDCP

DS90UH949-Q1
SNLS453 – NOVEMBER 2014
www.ti.com
• One master generates a repeated Start while another master sends a Stop.
Note that these restrictions mainly apply to accessing the same register offsets within a specific I2C slave.
8.5.4 Multi-Master Access to Device Registers for Newer FPD-Link III Devices
When using the latest generation of FPD-Link III devices, DS90UH949-Q1 or DS90UH940-Q1/DS90UH948-Q1
registers may be accessed simultaneously from both local and remote I2C masters. These devices have internal
logic to properly arbitrate between sources to allow proper read and write access without risk of corruption.
Access to remote I2C slaves would still be allowed in only one direction at a time .
8.5.5 Multi-Master Access to Device Registers for Older FPD-Link III Devices
When using older FPD-Link III devices, simultaneous access to serializer or deserializer registers from both local
and remote I2C masters may cause incorrect operation, thus restrictions should be imposed on accessing of
serializer and deserializer registers. The likelihood of an error occurrence is relatively small, but it is possible for
collision on reads and writes to occur, resulting in an errored read or write.
Two basic options are recommended. The first is to allow device register access only from one controller. This
would allow only the Host controller to access the serializer registers (local) and the deserializer registers
(remote). A controller at the deserializer would not be allowed to access the deserializer or serializer registers.
The second basic option is to allow local register access only with no access to remote serializer or deserializer
registers. The Host controller would be allowed to access the serializer registers while a controller at the
deserializer could access those register only. Access to remote I2C slaves would still be allowed in one
direction .
In a very limited case, remote and local access could be allowed to the deserializer registers at the same time.
Register access is guaranteed to work correctly if both local and remote masters are accessing the same
deserializer register. This allows a simple method of passing control of the Bidirectional Control Channel from
one master to another.
8.5.6 Restrictions on Control Channel Direction for Multi-Master Operation
Only one direction should be active at any time across the Bidirectional Control Channel. If both directions are
required, some method of transferring control between I2C masters should be implemented.
36
Submit Documentation Feedback
Product Folder Links: DS90UH949-Q1
Copyright © 2014, Texas Instruments Incorporated