Xilinx DS215 LogiCORE IP Binary Counter, Data Sheet
Contents
1. 1 Available only when in fabric legacy mode Implement using Fabric Latency 1 and Feedback Latency 0 DS215 March 1 2011 Product Specification www xilinx com 2 XILINX Binary Counter v11 0 CORE Generator Graphical User Interface Parameters The CORE generator GUI parameters for this module are described below Implement using Sets the implementation type to Fabric or DSP48 Output Width Specifies the width of the counter Restrict Count When this parameter is true the counter only counts up or down to the value specified in the Final Count Value parameter When it is false the counter counts up to the maximum value that can be represented using the specified output width This option is mutually exclusive with the up down counter option and with synchronous set controls Final Count Value When Restrict Count true this parameter specifies the hex representation of the upper limit of the counter Increment Value Specifies in hex the increment value of the counter When Restrict Count is false the valid range is 1 to 2Output Width _ 1 When Restrict Count is true the valid settings for Increment Value are governed by the equation Final Count Value Increment Value Integer for up counters and 2Output Width _ Final Count Value Increment Value Integer for down counters Count Mode This parameter specifies whether the counter counts up down or has its direction specified on the UP pin up2. The par options used were par ol high Clock frequency does not take clock jitter into account and should be derated by an amount appropriate to the clock source jitter specification The maximum achievable clock frequency and the resource counts may also be affected by other tool options additional logic in the FPGA device using a different version of Xilinx tools and other factors The Xilinx Xplorer script can be used to find the optimal settings All characterization was done using the following parameter settings unless otherwise noted e Count Mode UPDOWN e Latency Configuration Automatic e Feedback Latency Configuration Automatic e Increment Value 1 e Final Count Value 4B2A189 fabric and AFOC3 DSP48 e all else default unless otherwise noted DS215 March 1 2011 www xilinx com 8 Product Specification XILINX Binary Counter v11 0 Table 3 Fabric Counter Virtex 5 Part XC5VSX50T 1 Load 1 Restrict Count 2 Description Sml Med Lrg Sml Med Lrg Sml Med Lrg Output Width 18 47 200 18 47 200 18 47 200 Max Clock Frequency 450 433 353 444 407 316 452 450 378 MHz LUT6 FF pairs 19 92 437 19 137 770 25 129 462 LUTs 19 71 389 19 71 529 22 76 418 Flip flops 18 86 419 18 132 751 25 128 454 DSP48Es 0 0 0 0 0 0 0 0 0 1 Load test cases are for a counter with the following parameter values Loadable true Load Sense Active_High 2 Re
3. SSET SINIT take priority over LOAD Note that if SCLR SSET SINIT or LOAD are affected by CE specified in the Synchronous Controls and Clock Enable CE Priority parameter a low CE value causes these signals to be ignored For example if SCLR is affected by CE then with a low CE LOAD appears to override SCLR contrary to what is presented above However because SCLR has no effect when CE is low this is the correct effect Discussion of Restricted Counters The restricted counter option is implemented using an equality test rather than a greater than or equal to test This means that if the counter somehow manages to skip the Final Count Value value it keeps going Therefore there are restrictions on allowable parameters for restricted counters e Count Mode cannot be UPDOWN e SSET must be false Additionally there are restrictions added by pipelining as discussed in Pipelined Operation and there are further restrictions that differ for up counters and down counters Up Counters Restricted up counters count up by Increment Value until Q Final Count Value The counter resets to 0 during the clock cycle after Q Final Count Value There are two basic restrictions 1 Final Count Value must be an integer multiple of Increment Value 2 Increment Value must be less than or equal to Final Count Value In addition the following formulae must be satisfied lt value gt IncrementValue Integer lt value gt lt Final Count
4. Value where lt value gt is any of the following e Init Value if SINIT is used e AINIT Value for power on reset e Any value loaded on the L data port Down Counters Restricted down counters count down by Increment Value until Q Final Count Value The counter resets to 0 during the clock cycle after Q Final Count Value and the counter continues counting down wrapping around There are two basic restrictions Output Width 1 Final Count Value must be an integer multiple of Increment Value Output Width 2 Increment Value must be less than or equal to 2 Final Count Value In addition the following formulae must be satisfied DS215 March 1 2011 www xilinx com 6 Product Specification g XILINX Binary Counter v11 0 C Width lt value gt Increment Value Integer either lt value gt gt Final Count Value or lt value gt 0 where lt value gt is any of the following e Init Value if SINIT is used e AINIT Value for power on reset e Any value loaded on the L data port Use of LOAD The Counter core can check on instantiation for sensible Init Value and power on reset value but it cannot check the data loaded on the L data port Because of this erroneous values loaded will cause unexpected behavior in the counter For example if a counter is given Final Count Value 8 and Increment Value 2 loading in 3 will cause it to count the odd numbers and completely miss the limit value Load Supp
5. amp XILINX LogiCORE IP Binary Counter v11 0 DS215 March 1 2011 Introduction The Xilinx LogiCORE IP Binary Counter core provides LUT and single XtremeDSP slice counter implementations The Binary Counter is used to create up counters down counters and up down counters with outputs of up to 256 bits wide Support is provided for one threshold signal that can be programmed to become active when the counter reaches a user defined count The upper limit of the count is user programmable and the counter s increment value is user defined When the counter reaches terminal count or the count to value the next count is zero Features e Drop in module for Virtex 7 and Kintex 7 Virtex 6 Virtex 5 Virtex 4 Spartan 6 Spartan 3 XA Spartan 3E XA Spartan 3A 3AN 3A DSP XA FPGAs e Backwards compatible with version 9 1 e Generates up down and up down counters e Supports fabric implementation counters ranging from 1 to 256 bits wide e Supports DSP48 implementation counters ranging from 1 to 36 or 48 bits wide varies with device family e Pipelining added for maximal speed performance e Predictive detection used for threshold and terminal count detection e Optional synchronous set and synchronous init capability for legacy fabric implementations e Optional user programmable threshold outputs e Optional clock enable and synchronous clear e Counter increment value is user defined e User programmable
6. GUI and XCO Parameters GUI Name Component Name Default Value c_counter_binary_v11_0 Valid Range XCO Parameter Component_Name Implement using Fabric Implementation Output Width 16 1 to 256 fabric Output_Width 1 to 36 or 48 DSP48 Increment Value 1 1 unrestricted 1 to 2 Output Width 4 Increment_Value Latency Configuration Manual Latency_Configuration Latency 1 1 to 32 Latency Feedback Latency Manual Fb_Latency_Configuration Configuration Feedback Latency 0 0to4 Fb_Latency Clock Enable false CE Synchronous Clear false SCLR Synchronous Set false SSET Synchronous Init false SINIT Loadable false Load Load Sense Active_High Load_Sense Restrict Count false Restrict_Count Final Count Value 1 1 to 2 Output Width 2 Final_Count_Value Sync Threshold Output Active_Low Sync_Threshold_Output Threshold Value 1 restricted 0 to Final Count Value Threshold_Value unrestricted O to 2 Output Width 4 Count Mode UP UP DOWN UPDOWN Count_Mode Sync Set and Clear Reset Priority Reset_Overrides_ Set Sync_Ctrl_Priority Synchronous Controls and Clock Enable CE Priority Sync_Overrides_CE Sync_CE_Priority Power on Reset Init Value O to 2 Output Width 4 AINIT_Value Sync INIT value restricted 0 to Final Count Value unrestricted O to 2 Output Width 4 SINIT_Value 1 See the list above for an explanation of In
7. MHz This is achieved by splitting the carry chain of the main count operation into splices and pipelining The number of splices required is a function of the counter bit width and the family in question Feedback Latency Configuration and Feedback Latency refer to the latency in the terminal count feedback circuit and hence apply only to restricted counters The total amount of latency gives the number of cycles by which the terminal count detection must predict the terminal count value When Feedback Latency Configuration is set to Manual Feedback Latency can be set to a specific number for specific feedback latency By setting Feedback Latency Configuration to Automatic the feedback latency for maximal performance will be calculated internally and used in place of Feedback Latency Performance and Resource Utilization Tables 3 to 6 provide counter performance and resource usage for a number of different configurations The maximum clock frequency results were obtained by double registering input and output ports to reduce dependence on I O placement The inner level of registers used a separate clock signal to measure the path from the input registers to the first output register through the core The resource usage results do not include the above characterization wrapper registers and represent the true logic used by the core LUT counts include SRL16s or SRL32s according to device family The map options used were map pr b ol high
8. count limit e For use with Xilinx CORE Generator and Xilinx System Generator for DSP 13 1 Product Specification LogiCORE IP Facts Table Core Specifics Virtex 7 and Kintex 7 Virtex 6 Virtex 5 Virtex 4 Spartan 6 Spartan 3 XA Spartan 3E XA Spartan 3A 3AN 3A DSP XA Supported Device Family Supported User Not Applicable Resources Frequency Configuration LUTs FFs Dor ERE Max Freq Virtex 5 18 bit fabric up down 19 18 0 0 450 MHz counter Provided with Core Documentation Product Specification Design Files Netlist Example Design Not Provided Test Bench Not Provided Constraints File Not Applicable VHDL behavioral model in the xilinxcorelib library VHDL UniSim structural model Verilog UniSim structural model Simulation Model Tested Design Tools Design Entry CORE Generator tool 13 1 Tools System Generator for DSP 13 1 Mentor Graphics ModelSim 6 6d Cadence Incisive Enterprise Simulator IES 10 2 Simulation Synopsys VCS and VCS MX 2010 06 ISIM 13 1 Synthesis Tools NA Support Provided by Xilinx Inc 1 For a complete listing of supported devices see the release notes for this core 2 For more complete device performance numbers see Performance and Resource Utilization page 8 Copyright 2006 2009 2011 Xilinx Inc XILINX the Xilinx logo ISE Kintex Spartan Virtex and other designated bra
9. crement Value range when Restrict Count is true DS215 March 1 2011 Product Specification www xilinx com g XILINX Binary Counter v11 0 Core Use through CORE Generator The CORE Generator GUI performs error checking on all input parameters Resource estimation and latency information is also available Several files are produced when a core is generated and customized instantiation templates for Verilog and VHDL design flows are provided in the veo and vho files respectively For detailed instructions see the CORE Generator software documentation Simulation Models The core has a number of options for simulation models e VHDL behavioral model in the xilinxcorelib library e VHDL UniSim structural model e Verilog UniSim structural model Xilinx recommends that simulations utilizing UniSim based structural models are run using a resolution of 1 ps Some Xilinx library components require a 1 ps resolution to work properly in either functional or timing simulation The UniSim based structural models might produce incorrect results if simulation with a resolution other than 1 ps See the Register Transfer Level RTL Simulation Using Xilinx Libraries section in Synthesis and Simulation Design Guide for more information This document is part of the ISE Software Manuals set available at www xilinx com support software_manuals htm Core Use through System Generator The Binary Counter core is available through Xilinx Sys
10. down Sync Threshold Output When this parameter equals true the THRESHO combinatorial output is generated Threshold Value Specifies the value at which the THRESH0 value is activated as a hex value Loadable Activating the LOAD pin Loadable true allows the value on the L N 0 input port to pass through the logic and be loaded into the output register on the next active clock edge See the section Use of LOAD for more information Load Sense Specifies Active_High or Active_Low LOAD pin CE When set to true the module is generated with a clock enable input Power on Reset Init Value Specifies in hex the value that the output initializes to during power up reset Synchronous Clear SCLR Specifies if an SCLR pin is to be included SSET Specifies if an SSET pin is to be included SSET pin is not valid in DSP48 implementations See Sync Set and Clear Reset Priority for SCLR SSET priorities SINIT Specifies if an SINIT pin is to be included which when asserted synchronously sets the output value to the value defined by Init Value Note that if SINIT is present then neither SSET nor SCLR may be present SINIT pin is not valid in DSP48 implementations Init Value Specifies in hex the value that the output initializes to when SINIT is asserted The Init Value is ignored if SINIT is false Synchronous Controls and Clock Enable CE Priority This parameter controls whether or not the SCLR and if fabric SSET and SINIT input
11. ein none of the Information may be copied reproduced distributed republished downloaded displayed posted or transmitted in any form or by any means including but not limited to electronic mechanical photocopying recording or otherwise without the prior written consent of Xilinx DS215 March 1 2011 www xilinx com 11 Product Specification
12. ion Sml Med Sml Med Sml Med Output Width 35 48 35 48 35 48 Max Clock Frequency MHz 169 170 169 170 169 170 LUTs 11 16 13 18 13 18 Flip flops 21 21 59 72 59 72 DSP48As 1 1 1 1 1 1 1 Load test cases are for a counter with the following parameter values Load true ALL DSP48 tests have Restrict Count true Support Xilinx provides technical support for this LogiCORE product when used as described in the product documentation Xilinx cannot guarantee timing functionality or support of product if implemented in devices that are not defined in the documentation if customized beyond that allowed in the product documentation or if changes are made to any section of the design labeled DO NOT MODIFY Refer to the IP Release Notes Guide XTP025 for further information on this core There is a link to all the DSP IP and then to each core For each core there is a master Answer Record that contains the Release Notes and Known Issues list for each core The following information is listed for each version of the core e New Features e Bug Fixes e Known Issues Ordering Information This LogiCORE IP module is included at no additional cost with the Xilinx ISE Design Suite software and is provided under the terms of the Xilinx End User License Agreement Use the CORE Generator software included with the ISE Design Suite to generate the core For more information please visit the core page Please contact your l
13. is qualified by CE When set to Sync_Overrides_CE the synchronous control overrides the CE signal When set to CE_Overrides_Sync SCLR has an effect only when CE is high Note that on the fabric primitives the SCLR and SSET controls override CE so choosing CE_Overrides_Sync generally results in extra logic Sync Set and Clear Reset Priority Controls the relative priority of SCLR and SSET When set to Reset_Overrides_Set SCLR overrides SSET The default is Reset_Overrides_Set as this is the way the primitives are arranged Making SSET take priority requires extra logic DS215 March 1 2011 www xilinx com 3 Product Specification XILINX Binary Counter v11 0 e Latency Configuration Automatic or Manual Automatic sets optimal latency for maximum speed Manual allows user to set Latency to one of the allowed values e Latency Value used for latency when Latency Configuration is set to Manual See the section Pipelined Operation for more information e Feedback Latency Configuration Automatic or Manual Automatic sets optimal feedback latency for maximum speed Manual allows user to set Feedback Latency to one of the allowed values e Feedback Latency Value used for latency when Feedback Latency Configuration is set to Manual See the section Pipelined Operation for more information Table 2 is a cross reference table from the GUI parameters listed above to the XCO parameter names in the XCO file Table 2 CORE Generator
14. nds included herein are trademarks of Xilinx in the United States and other countries MATLAB and Simulink are registered trademarks of The MathWorks Inc All other trademarks are the property of their respective owners DS215 March 1 2011 Product Specification www xilinx com 1 XILINX Pinout Binary Counter v11 0 SINIT fabric implementation in legacy mode only DS215_01_111810 Figure 1 Core Symbol Signal names for the core symbol are shown in Figure 1 and described in Table 1 Note that Figure 1 shows the SSET and SINIT pins which appear only on legacy fabric implementations The fabric legacy mode has been provided to preserve backwards compatibility but allow performance to be improved This is where Implement using Fabric Latency 1 and FB_Latency 0 Table 1 Core Signal Pinout Signal Direction Description CLK Input Rising edge clock signal UP Input Controls the count direction on an up down counter Counts up when high down when low CE Input Active high Clock Enable SCLR Input Synchronous Clear forces the output to a low state when driven high THRESHO Output User programmable active high threshold signal Q N 0 Output Output L N 0 Input Load data port LOAD Input Load control signal SSET Input Synchronous Set forces the output to a high state when driven high SINIT Input Synchronous Initialize forces the outputs to a user defined state when driven high
15. ocal Xilinx sales representative for pricing and availability of additional Xilinx LogiCORE modules and software Information about additional Xilinx LogiCORE modules is available on the Xilinx IP Center Revision History Date Version Description of Revisions 7 13 06 9 0 Updated to ISE Tools 8 2i 4 24 09 11 0 Updated to ISE tools 11 1 added XtremeDSP slice implementations and new family support for Virtex 6 and Spartan 6 devices 03 01 11 11 1 Support added for Virtex 7 and Kintex 7 ISE Design Suite 13 1 DS215 March 1 2011 www xilinx com 10 Product Specification XILINX Binary Counter v11 0 Notice of Disclaimer Xilinx is providing this product documentation hereinafter Information to you AS IS with no warranty of any kind express or implied Xilinx makes no representation that the Information or any particular implementation thereof is free from any claims of infringement You are responsible for obtaining any rights you may require for any implementation based on the Information All specifications are subject to change without notice XILINX EXPRESSLY DISCLAIMS ANY WARRANTY WHATSOEVER WITH RESPECT TO THE ADEQUACY OF THE INFORMATION OR ANY IMPLEMENTATION BASED THEREON INCLUDING BUT NOT LIMITED TO ANY WARRANTIES OR REPRESENTATIONS THAT THIS IMPLEMENTATION IS FREE FROM CLAIMS OF INFRINGEMENT AND ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE Except as stated her
16. or make sure the counter is simple count by 1 and that a value is never loaded beyond Final Count Value Pipelined Operation Pipelining the terminal count detection requires that the actual value detected is the terminal count value minus some multiple of the Increment Value value where the multiple is determined by the full cycle latency This adds further restrictions to the valid combinations of Increment Value and Final Count Value A run time assertion warning flags if a value is loaded which would cause the actual terminal count value to be missed To allow for high performance four new parameters have been added to the core Latency Configuration Latency Feedback Latency Configuration and Feedback Latency The first two describe the number of cycles the core takes to recover from SCLR or from a LOAD value since it is the number of registers in the forward data path When Latency Configuration is set to Manual Latency can be set to a specific number for specific latency By setting Latency Configuration to Automatic the latency for maximal performance is calculated internally and used in DS215 March 1 2011 www xilinx com 7 Product Specification g XILINX Binary Counter v11 0 place of Latency Maximal performance is defined as an operating frequency greater than or equal to the nominal operating speed of a fully pipelined XtremeDSP slice For Virtex4 10 this is 400MHz For Virtex5 1 this is 450MHz For Spartan 3A DSP this is 250
17. ort The load operation in an XtremeDSP slice requires opmode control The opmode control affects some of the same bits that are controlled to allow the terminal count reset feature For the bits affected external gating is required This either impacts performance or requires an additional layer of latency in the feedback path An extra layer of latency in the load path requires external registers for the D port of DSP48A Spartan 3A DSP Spartan 6 and on the C register used for the Increment Value Despite being a constant the Increment Value is registered so that the recover from SCLR latency matches the LOAD latency The latency of the counter for the XtremeDSP slice implementation is therefore width dependant and varies as a function of Restrict Count Loadable Load Sense Output Width and the device family chosen The Load Enable in v9 0 and earlier has been deprecated LOAD is always subject to CE if present In Virtex 4 the A B concatenated port width is 36 bits hence the output width is also limited to 36 bits when LOAD is used Moreover the detection of the terminal count has been further improved in version 11 0 but to maintain backward compatible behavior the improved detection cannot be used when the counter is loadable Therefore it is strongly recommended that LOAD is not used with restricted counters if such functionality is required use external logic to create a greater than or equal to test rather than an equal to test
18. strict Count test cases are for a counter with the following parameter values Restrict Count true Count Mode UP Table 4 XtremeDSP Slice Counter Virtex 5 Part XC5VSX50T 1 Load High Load Low Description Sml Med Sml Med Sml Med Output Width 35 48 35 48 35 48 Max Clock Frequency MHz 450 450 450 450 450 450 LUT6 FF pairs 7 43 45 94 45 94 LUTs 7 10 9 12 9 12 Flip flops 7 43 45 94 45 94 DSP48Es 1 1 1 1 1 1 1 Load test cases are for a counter with the following parameter values Loadable true ALL DSP48 tests have Restrict Count true Table 5 Fabric Counter Spartan 3A DSP Part XC3SD3400A 4 o Load Restrict Count Description Sml Med Lrg Sml Med Lrg Sml Med Lrg Output Width 18 47 200 18 47 200 18 47 200 Max Clock Frequency 248 205 193 217 197 187 261 243 230 MHz LUTs 49 94 512 88 165 937 56 104 554 Flip flops 36 102 464 54 172 840 57 123 549 DSP48As 0 0 0 0 0 0 0 0 0 1 Load test cases are for a counter with the following parameter values Load true Load Sense Active_High 2 Restrict Count test cases are for a counter with the following parameter values Restrict Count true Count Mode UP DS215 March 1 2011 www xilinx com 9 Product Specification XILINX Binary Counter v11 0 Table 6 XtremeDSP Slice Counter Spartan 3A DSP Part XC3SD3400A 4 Load High Load Low Descript
19. tem Generator for DSP a design tool that enables the use of the model based design environment Simulink software for FPGA design The Binary Counter core is one of the DSP building blocks provided in the Xilinx DSP blockset for Simulink The Binary Counter core can be found in the Xilinx Blockset in the Math section The block is called Counter See the System Generator User Manual for more information Migrating to Binary Counter v11 0 from Earlier Versions Updating from Binary Counter v9 0 and later The CORE Generator core update feature can be used to update an existing Binary Counter XCO file to version 11 0 of the core The core can then be regenerated to create a new netlist See the CORE Generator documentation for more information on this feature Updating from Versions Prior to Binary Counter v9 0 It is not currently possible to automatically update versions of the Binary Counter core prior to v9 0 Xilinx recommends that customers use the Binary Counter v11 0 GUI to customize a new core Note that some features and configurations may be unavailable in Binary Counter v11 0 Also some port names may differ between versions DS215 March 1 2011 www xilinx com 5 Product Specification XILINX Binary Counter v11 0 Priorities of Input Signals e SCLR SSET The priority of SCLR versus SSET can be configured using the Sync Set and Clear Reset Priority parameter as described above e LOAD The synchronous controls SCLR
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