Channel Types

This standard defines two types of communication channels that are used across the system:

Stream Channel

A unidirectional, asynchronous channel of continuous, N-bit word data along with a signal indicating if it is ready to send/receive data. Two directions are defined:

Read:

Streams that transmit data from a device to the host computer.

Write:

Streams that transmit data to a device from the host computer.

Register Channel

A synchronous, bidirectional, addressed digital bus to access registers. Registers can be Read-only, Write-only or Read/Write. Channels of this type MUST indicate a successful or failed completion of a register access operation. (e.g., an access to a non-existent address or a non-allowed operation will signal an error.)

Note

Both the controller and the devices can hold registers. Controller registers are arranged in a fixed address map and accessed through the configuration channel. Device registers follow the address map defined on each device datasheet and are accessed through the device register interface.