3.4. DSP Worksheet
Each row in the DSP section represents a DSP design module where all instances of the module have the same configuration, clock frequency, toggle percentage, and register usage. If some (or all) DSP or multiplier instances have different configurations, you must enter the information in different rows. Specify the following information for each DSP or multiplier module:
- Number of instances
- Clock frequency (in MHz)
- Toggle percentage of the data outputs
- Inputs and outputs that are registered or not
- Module pipelined or not
|Module||Enter a name for the DSP module in this column. This is an optional value.|
|Configuration||Select the DSP block configuration for the module.|
|# of Instances||
Enter the number of DSP block instances that have the same configuration, clock frequency, toggle percentage, and register usage. This value is independent of the number of dedicated DSP blocks you use.
For example, it is possible to use four 9 × 9 simple multipliers that are implemented in the same DSP block in the FPGA devices. In this case, the number of instances would be four.
To determine the maximum number of instances you can fit in the device for any particular mode, follow these steps:
|Clock Freq (MHz)||Enter the clock frequency for the module in MHz. This value is limited by the maximum frequency specification for the device family.|
Enter the average percentage of DSP data outputs toggling on each clock cycle. The toggle percentage ranges from 0 to 50%. The default value is 12.5%. For a more conservative power estimate, use a higher toggle percentage.
In addition, 50% corresponds to a randomly changing signal (because half the time the signal changes from a 0-to-0 or 1-to-1). This is considered the highest meaningful toggle rate for a DSP block.
Select whether the inputs of the dedicated DSP block or multiplier block are registered using the dedicated input registers. If you use the dedicated input registers in the DSP or multiplier block, select Yes. If the inputs are unregistered or registered using registers in the ALMs or the look-up table (LUTs), select No.
Select whether the outputs of the dedicated DSP block or multiplier block are registered using the dedicated input registers. If you use the dedicated output registers in the DSP or multiplier block, select Yes. If the inputs are unregistered or registered using registers in ALMs or LUTs, select No.
Select whether or not the dedicated DSP block is pipelined.
|Thermal Power (W)–Routing||
This shows the power dissipation due to estimated routing (in watts).
Routing power depends on placement and routing, which is a function of design complexity. The values shown represent the routing power based on experimentation of more than 100 designs.
|Thermal Power (W)–Block||This shows the estimated power consumed by the DSP blocks (in watts). This value is automatically calculated.|
|Thermal Power (W)–Total||This shows the estimated power (in watts), based on your inputs. It is the total power consumed by the DSP blocks and is equal to the routing power and block power. This value is automatically calculated.|
|User Comments||Enter any comments. This is an optional entry.|
For more information about the DSP block configurations of the supported device families, refer to the “DSP Blocks”, “Variable Precision DSP Blocks”, or “Embedded Multipliers” chapter of the respective device handbook.
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