Stream Link Interfaces - Xilinx MicroBlaze Reference Manual

Stream Link Interfaces

MicroBlaze can be configured with up to 16 Fast Simplex Link (FSL) or AXI4-Stream interfaces,
each consisting of one input and one output port. The channels are dedicated uni-directional point-
to-point data streaming interfaces. The parameter C_STREAM_INTERCONNECT is used to select
FSL or AXI4.
For detailed information on the FSL interface, please refer to the Fast Simplex Link (FSL) Bus data-
sheet, DS449, in the Xilinx EDK IP Documentation. For detailed information on the AXI4-Stream
interface, please refer to the AMBA
The interfaces on MicroBlaze are 32 bits wide. A separate bit indicates whether the sent/received
word is of control or data type. The get instruction in the MicroBlaze ISA is used to transfer
information from a port to a general purpose register. The put instruction is used to transfer data in
the opposite direction. Both instructions come in 4 flavors: blocking data, non-blocking data,
blocking control, and non-blocking control. For a detailed description of the get and put instructions,
please refer to
Hardware Acceleration
Each link provides a low latency dedicated interface to the processor pipeline. Thus they are ideal
for extending the processors execution unit with custom hardware accelerators. A simple example is
illustrated in
FSL or AXI4-Stream is used.
This method is similar to extending the ISA with custom instructions, but has the benefit of not
making the overall speed of the processor pipeline dependent on the custom function. Also, there are
no additional requirements on the software tool chain associated with this type of functional
extension.
MicroBlaze Processor Reference Guide
UG081 (v14.7)
Chapter 5, MicroBlaze Instruction Set
Figure 2-25. The code uses RFSLx to indicate the used link, independent of whether
Example code:
// Configure f
x
cput Rc,RFSLx
// Store operands
put Ra, RFSLx // op 1
put Rb, RFSLx // op 2
// Load result
get Rt, RFSLx
Figure 2-25: Stream Link Used with HW Accelerated Function
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®
4 AXI4-Stream Protocol Specification, Version 1.0 document.
Architecture.
Link x
MicroBlaze
Register
File
Link x
Stream Link Interfaces
Custom HW Accelerator
Op1Reg Op2Reg
ConfigReg
f
x
ResultReg
f
x
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