The Xilinx DSP48 Macro offers a very easy interface, which abstracts the slice of Xilinx DSP48. It also simplifies the dynamic operation. This it achieves by making possible the multiple operations specification through some arithmetic expressions that are user defined. Furthermore, these specified operations can be enumerated, as well as chosen by a user through a single port present on your generated core.
In addition, the Xilinx DSP48 offers a very easy interface to your Xilinx DSP48 slice by all abstraction of opmode, inmode, alumode, and subtract controls into an SEL port. Furthermore, all the RST and CE controls are categorized in a single SCLR and CE port respectively. The abstraction here enhances HDL’s portability between the device families.
Also, the DSP48 Macro helps in supporting a latency model whereby extra register stages are usually included so that all the input into the output paths features a similar latency. It backs three latency modes, which are expert, tiered, and automatic.
The tiered and automatic are the square types of latency models. Here, the difference is that the auto offers complete pipelines. The tiered on the other hand allows for finer control. Now, this could be very useful when making use of Xilinx DSP48 slices to serve as processing engines.
Alternatively, it is possible to remove the other pipeline stages in order to make use of the minimum resources. Applications that should make use of the Xilinx DSP48 are those that don’t need complete control of these DSP slices. They are also useful in applications whereby portability becomes a very high priority.
Lastly, the Xilinx DSP48 supports the instructions of the slice when enjoying the best and maximum performance.
What are the Main Benefits and Features of Xilinx DSP48?
The main benefits and features of the Xilinx DSP48 include the following
- It can support about 64 instructions
- Configurable latency
- Supports the pre-adder of the DSP slice
- Abstracted and simplified interface to the DSP slice helps in enhancing the portability, code readability, and ease of use
- Support f two’s complement, signed input data
- Define the operation of the DSP slice through some arithmetic expressions that are user defined
- The ability to specify the optional clock enables as well as resets for each control path registers and data
What is DSP48 Block?
The Xilinx DSP48 block is known as the most complex of all the computational blocks available in the Xilinx FPGA. This block is known as an ALU (arithmetic logic unit), which is embedded in the FPGA fabric and is made up of three blocks which form a chain.
This computational chain present in the Xilinx DSP48 includes a subtract or add unit, that is connected to a specific multiplier, which is also connected to an eventual accumulate/subtract/add engine. The chain permits one DSP48n unit to integrate and implement the form’s functions. These functions include P +=Bx(A+D) or P=Bx(A+D)+C.
This DSP48 block is useful by SDAccel for performing many computational loads in the OpenCL kernels. Also, this synthesis flow in the SDAccel tool helps in automatically targeting the block.
What are the Design Recommendations of the Xilinx DSP48?
A good number of DSP designs work well with the architecture of the 7 series. In order to get the best benefit from using the architecture, you must understand the capabilities and features to ensure that the entry code of the design will take advantage of the resources. The resources of the DSP48E1 are automatically used for majority of the DSP functions as well as a good number of arithmetic functions.
Most of the time, the resources of the DSP ought to be inferred. Check out the documentation of the synthesis preferred for the guidelines so as to make sure of the right inference of DSP48E1 slice. The tool for synthesis helps in inferring the resources. The instantiation is useful in directly accessing the features of the Xilinx DSP48 slice. The recommendations for DSP48E1 use include:
- Make use of signed values in the HDL source
- Use CLB (configurable logic block) in carrying logic so as to implement the small counters, adders, multipliers.
- Consider making use of time multiplexing in the design
- Cascade making use of dedicated resources instead of fabric, using just one column to ensure lowest power and highest performance
- Set to NONE the USE_ MULT when making use of just the logic/adder unit to help in saving power
- Pipeline for lower power and performance, both in the fabric and slice of the Xilinx DSP48
- Make use of CLB distributed RAM, CLB SRLs, or/and block RAM that helps in storing the filter coefficients
What are the Slice Features of Xilinx DSP48?
The Xilinx DSP48 slice is made up of a multiplier, and then an accumulator follows. Three or more pipeline registers are needed for the multiply-accumulate and multiply operations to function and run at high speed. This first stage’s multiply operation generates two products, which have to be added altogether during the 2nd stage.
When at most two registers are present in multiplier designs, then the M register has to be used in saving the power as well as improving the performance always.
The Logic Unit and Add/Sub operations need two or more pipeline registers (output, input) to function and run at very full speed. The Xilinx DSP slice’s cascade capabilities are very efficient in the implementation of pipelined filters of high speed, which are built on adder cascades rather than adder trees.
The control of the multiplexers is achieved via dynamic control signals like CARRYINSEL, ALUMODE, and OPMODE. This enables great flexibility. Also, designs making use of dynamic opmodes and registers are more equipped to work with the capabilities of the xilinx DSP48 slice compared to the combinatorial multiplies.
Conclusion
We hope you have learnt the main features, benefits, and design recommendations of the Xilinx DSP48. You can go over the article again, and if there’s any aspect you need more explanation on, do well to let us know.
