Multiple Clock System Design Danny Mok Altera HK FAE (amok@altera.com) Copyright 1997 Altera Corporation 2/22/2021P1 favara
Copyright © 1997 Altera Corporation 2/22/2021 P.1 Multiple Clock System Design Danny Mok Altera HK FAE (dmok@altera.com)
Example DFF F F F clk1 CLRN CLRN clk2 ClkI and Clk2 are the clock which running at different frequency Copyright 1997 Altera Corporation 2/22/2021P2 favara
Copyright © 1997 Altera Corporation 2/22/2021 P.2 Example Clk1 and Clk2 are the clock which running at different frequency
Timing Analyzer ro Timing Analyzer Registered Performance Clock: clk1(1 paths) Info: One or more paths have been found between registers controlled by different Source:: 1.Q Destination:: 2.Q clocks-can't calculate registered performance for those paths Clock period: 3. 4ns Frequency: 294. 11MHz Start Stop List Paths Copyright 1997 Altera Corporation 2/22/2021P favara
Copyright © 1997 Altera Corporation 2/22/2021 P.3 Timing Analyzer
Information from Timing analyzer □区 Registered Performance Clock: clk1(1 paths) cili paths Registered Performance ea Timing analyzer Clock: clk1 (1 paths) Registered performance Source:: 1.0 Clock clk2(1 paths Destination:: 2.0 ource 150 Destination:: 5.0 Clock period. 3. 4n Frequency. 294. 11MHz Clock period: 3. 4ns Frequency: 294.11MH Clock period: 6.6ns equency: 151. MHz Start Stop Start st List Paths Sta Stop List Paths
Copyright © 1997 Altera Corporation 2/22/2021 P.4 Information from Timing Analyzer
Information of clk1 DFF F F F clk1 CLRN CLRN clk2 Registered Performance ClkI can run at max 294. MHZ Clock period: 3. 4ns Frequency: 294.11MH: Copyright 1997 Altera Corporation 2/22/2021P Start SLop List Paths favara
Copyright © 1997 Altera Corporation 2/22/2021 P.5 Information of Clk1 Clk1 can run at max. 294.11MHz
Information of clk2 DFF F F F clk1 CLRN CLRN clk2 &tIming Analyzer 匚区 Registered Performance Clock: [ck2 1 paths Source:: 4.0 Clk2 can run at max 5.0 151.51MHZ Clock period: 6.6n Frequency: 151.51MHz Copyright 1997 Altera Corporation 2/22/2021P List Paths favara
Copyright © 1997 Altera Corporation 2/22/2021 P.6 Information of Clk2 Clk2 can run at max. 151.51MHz
What do you expect tool to help you DFF F F F clk1 CLRN CLRN clk2 Copyright 1997 Altera Corporation 2/22/2021P7 favara
Copyright © 1997 Altera Corporation 2/22/2021 P.7 What do you expect tool to help you
Possible solution 0 d OUTPUT CLRN 器乙 clk2 Copyright 1997 Altera Corporation 2/22/2021P favara
Copyright © 1997 Altera Corporation 2/22/2021 P.8 Possible Solution
Information Missing DFF F o F clk1 CLRN CLRN clk2 Max+ Plus l does not provide any information about this path Q: What kind of assign option is available to control the placement of this path Tsu, TcO, Tpd, Fmax, Clique, or Logic Option? Copyright 1997 Altera Corporation 2/22/2021P favara
Copyright © 1997 Altera Corporation 2/22/2021 P.9 Information Missing ◼ Max+Plus II does not provide any information about this path ◼ Q : What kind of Assign Option is available to control the placement of this path ? – Tsu, Tco, Tpd, Fmax, Clique, or Logic Option ? ?
Look Step by Step ■ Possible Assign Option Tpd No! Tpd can affect the logic placement but only can apply to O -Tsu No! Tsu can affect the logic placement but only can apply to Input Tco No! Tco can affect the logic placement but only can apply to Output pin Copyright 1997 Altera Corporation 2/22/2021P10 favara
Copyright © 1997 Altera Corporation 2/22/2021 P.10 Look Step by Step ◼ Possible Assign Option – Tpd ? • NO! Tpd can affect the logic placement but only can apply to I/O pin – Tsu ? • NO! Tsu can affect the logic placement but only can apply to Input pin – Tco ? • NO! Tco can affect the logic placement but only can apply to Output pin