1. Introduction to VLSI Programming TU/e course 2IN30 Lecture 2: Control Handshake Circuits (1) Prof.dr.ir Kees van Berkel [Dr. Johan Lukkien] [Dr.ir. Ad Peeters]

2. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-102 TU/e Time table 2005 dateclass | labsubject Aug. 302 | 0 hoursintro; VLSI Sep. 63 | 0 hourshandshake circuits Sep. 133 | 0 hourshandshake circuits assignment Sep. 203 | 0 hoursTangram Sep. 27no lecture Oct. 4 no lecture Oct. 111 | 2 hoursdemo, fifos, registers | deadline assignment Oct. 181 | 2 hoursdesign cases; Oct. 251 | 2 hoursDLX introduction Nov. 11 | 2 hourslow-cost DLX Nov. 81 | 2 hourshigh-speed DLX Nov. 29deadline final report

3. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-103 TU/e Last Week – Lecture 1

4. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-104 TU/e Transistors CMOS is the dominant IC technology today (Complementary Metal Oxide Semiconductor) Two types of transistors are used –PMOS and NMOS Dimensions of transistors are scaled by  2 in every new generation –0.5  - 0.35  - 0.25  - 0.18  - 0.12  - 90n - 70n - … This halves their area and makes them faster

5. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-105 TU/e CMOS circuits Pull-up stack consisting of only P-mosts Pull-down stack consisting of only N-mosts Only inverting gates can thus be formed Vdd Vss + – V Pull-up Pull-down P N

6. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-106 TU/e Boolean functions and transistors Transistors can be put in series –Conducting only if all conducting –This implements an AND function Transistors can be put in parallel –Conducting if either is conducting –This implements an OR function Networks can build AND/OR functions

7. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-107 TU/e Production rules Production rules are guarded commands that specify (CMOS) gates –  F  z , G  z   Interpretation –do F then z:=true or G then z:=false od Guards must be mutually exclusive (environment) A gate is combinational if F  G is a tautology and it is sequential (state-holding) otherwise Guards must be stable: once a guard is true it must remain true until completion of transition

8. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-108 TU/e Combinational CMOS gates Guards of production rules are complementary  F  z ,  F  z   This translates into z = F Combinational functions can be decomposed into inverting boolean functions These can be implemented directly in CMOS transistor stacks

9. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-109 TU/e NAND gate z =  (a  b) Inverting function, hence single CMOS stage  a   b  z  –Two P-mosts in parallel a  b  z  –Two N-mosts in series Vss Vdd ab a b a b z z

10. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1010 TU/e AND gate z = a  b – a  b  z  –  a   b  z  Non-inverting function, hence two CMOS stages First stage: NAND-gate –  a   b  y  – a  b  y  Second stage: Inverter –  y  z  – y  z  Vss Vdd ab a b a b z z y

11. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1011 TU/e And-Or-Invert functions z =  (a  (b  c)) Inverting function, hence single CMOS stage  a  (  b   c)  z  –Three P-mosts a  ( b  c)  z  –Three N-mosts Vss Vdd a b a b z c c

12. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1012 TU/e Exclusive-Nor in 10 transistors z = a  b = (a  b)  (  a   b) =  (a  b)   (a  b) =  (  (a  b)  (a  b)) y =  (a  b)Nand-gate, 4 mosts z =  (y  (a  b))Or-And-Inv-gate, 6 mosts

13. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1013 TU/e Sequential CMOS gates Guards of production rules are not complementary  F  z , G  z   This translates into z = F  (z   G) –Or (equivalently)  z = G  (  z   F) This can be decomposed in two combinational functions y =  (F  (z   G)) and z =  y Combinational function F  (z   G) can be transformed into basic inverting functions

14. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1014 TU/e Realization of a Muller-C element Production rules –  a  b  z ,  a   b  z  Implementation –z = F  (z   G ) –z = a  b  (z  (a  b )) –z = (a  b)  (b  z)  (z  a) –z = majority(a,b,z) Maj a b z C z a b

15. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1015 TU/e Realization of a Muller-C element Vss Vdd a b a b z z a b z a b

16. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1016 TU/e Realization of a Muller-C element Vss Vdd a b a b z z a b z a b

17. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1017 TU/e Realization of an asymmetric C element Production rules –  a  b  z ,  b  z  Implementation –z = F  (z   G ) –z = (a  b)  (z  b) –z = b  (a  z) Or-And-Inv plus an inverter 8 transistors C z a b +

18. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1018 TU/e VLSI basics Vdd (power) Vss (ground) C + – V Charge Q wire gate

19. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1019 TU/e VLSI metrics dimensionless quantities (0.25  m CMOS): Aareagate equivalent (Nand, 4 mosts) (33  m 2, or 30,000 geq/mm 2 ) Ttimegate delay (0.35 nanosecond) (per basic inverting CMOS gate) Eenergytransition (1 picojoule) (per basic inverting CMOS stage)

20. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1020 TU/e This Week – Lecture 2

21. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1021 TU/e Handshake protocol Handshake between active and passive partner Communication is by means of alternating request (from active to passive) and acknowledge (from passive to active) signals Active: send request, then wait for acknowledge Passive: wait for request, then send acknowledge ActivePassive

22. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1022 TU/e Handshake component: sequencer Sequencer Master Task 1 Task 2

23. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1023 TU/e Four-phase handshake protocol Circuit level implementation has separate wires for request and acknowledge Four-phase handshake protocol implements return-to-zero of these wires Active Side Req := 1 ; Wait (Ack); Req := 0 ; Wait (-Ack); Passive Side Wait (Req); Ack := 1; Wait (-Req); Ack := 0; Req Ack

24. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1024 TU/e Handshake signaling active sidepassive side request a r acknowledge a k request a r time event sequence: a r  a k  a r  a k 

25. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1025 TU/e Handshake behaviors Let x i be boolean variables, and S i commands: skip always terminates without effect x  is a shorthand for x:= true and x  for x:= false S 1 ; S 2 denotes sequential execution of S 1 and S 2 S 1 || S 2 denotes parallel execution of S 1 and S 2 Program notation inspired by [Martin].

26. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1026 TU/e Handshake behaviors Let G i be boolean expressions. Selection [G 1  S 1 [] … [] G N  S N ] execute an arbitrary S i for which guard G i holds. When no guard holds then suspend execution until otherwise. Repetition  [G 1  S 1 [] … [] G N  S N ] repeatedly execute S i for which G i holds until all guards are false.

27. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1027 TU/e Useful shorthands ‘wait until’ [G] = [G  skip] Note: [G] ; S = [G  S] Unbounded repetition  [S] =  [true  S]

28. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1028 TU/e Useful shorthands Four-phase handshakes –a  = [ar] ; ak  ; [  ar] ; ak  –a  = ar  ; [ak] ; ar  ; [  ak] Two-phase handshakes –a  = [ar] ; ak  –a  = [  ar] ; ak  –a   = ar  ; [ak] –a   = ar  ; [  ak]

29. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1029 TU/e Reorder properties In the absence of timing assumptions, 1.One cannot observe the order of output transitions x1  ; x2  = x2  ; x1  = x1  || x2  2.One cannot fix the order of input transitions [x1] ; [x2] = [x2] ; [x1] = [x1] || [x2] = [x1  x2]

30. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1030 TU/e Enclosure and properties Enclosure –a  : S = [ ar] ; S ; ak  –a  : S = [  ar] ; S ; ak  Reorder property a  : b  = [a r ] ; ([b r ] ; b k  ) ; a k  = [b r ] ; ([a r ] ; a k  ) ; b k  = b  : a 

31. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1031 TU/e Decomposition rule Let program P = … S … and let a be a “fresh” channel Program P can be decomposed into two parallel processes: P’ = … a   ; a   … and  [a  : S ; a  ]

32. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1032 TU/e Some handshake components Repeater : [a  :  [b   ; b   ] ] Mixer :  [ [ a  : c   ; [a  : c   ] [] b  : c   ; [b  : c   ] ] ] Sequencer :  [[a  : (b   ; b   ; c   ) ] ; [a  : c   ]]  a b a ; b c | a c b

33. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1033 TU/e Handshake circuit: duplicator For each handshake on a 0  the duplicator produces two handshakes on a 1   [[a 0  : (a 1   ; a 1   ; a 1   ) ] ; [a 0  : a 1   ]] cf. Handshake behavior sequencer.

34. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1034 TU/e Time for a break

35. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1035 TU/e Production rules Production rules are guarded commands that specify (CMOS) gates –  F  z , G  z   Interpretation –do F then z:=true or G then z:=false od Guards must be mutually exclusive (environment) A gate is combinational if F  G is a tautology and it is sequential (state-holding) otherwise Guards must be stable: once a guard is true it must remain true until completion of transition

36. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1036 TU/e Behavior of a gate network Gate network is the union of all pairs of production rules (gates) The concurrent execution of this set of PRs amounts to [Martin]:  [ select a PR ; fire that PR] If guard of PR equals false, firing = skip (firing a PR is an atomic action)

37. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1037 TU/e Initializable A handshake component realization is initializable : when all inputs are false, the gate network must autonomously proceed to an initial state; when all passive inputs are false, the component must autonomously proceed to a state with all active outputs false.

38. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1038 TU/e Handshake components: realization From handshake notation to gate network in 8 steps: 1 Specify component in handshake notation. 2 Expand to individual boolean variables (wires). 3 Introduce auxiliary state variables (if required). 4 Derive a set of production rules that implements this refined specification. 5 Make production rules more symmetric (cheaper). 6 (Verify isochronic forks.) 7 Verify initialization constraints. 8 Analyze time, area, and energy.

39. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1039 TU/e Handshake components realizations Connector: trivial Repeater: alternative ‘symmetrizations’ Mixer: isochronic forks Sequencer: introduction of auxiliary variable Duplicator: up to you? Selector: up to you!

40. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1040 TU/e Connector realization Behavior:  [a  : b   ; a  : b   ] Expansion:  [ [a r ] ; b r  ; [b k ] ; a k  ; [  a r ] ; b r  ; [  b k ] ; a k  ] Production rules: b k  a k  a r  b r   b k  a k   a r  b r  A pair of wires (!): no area, no delay, no energy. a b

41. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1041 TU/e Repeater realization Behavior: [a  :  [b   ; b   ] ] Expansion: [ [a r ] ;  [ b r  ; [b k ] ; b r  ; [  b k ] ] ; a k  ] Production rules: false  a k  a r   b k  b r  true  a k  b k  b r  However, not initializable!  a b

42. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1042 TU/e Repeater realizations

43. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1043 TU/e Repeater: area, delay, energy Area: 2 gate equivalents Delay per cycle: 2 gate delays Energy per cycle: 2 transitions

44. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1044 TU/e Mixer realization Behavior:  [ [ a  : c   ; a  : c   [] b  : c   ; b  : c   ] ] Restriction:  a r   b r must hold at all times! Expansion:  [ [ [a r ] ; c r  ; [c k ] ; a k  ; [  a r ] ; c r  ; [  c k ] ; a k  [] [b r ] ; c r  ; [c k ] ; b k  ; [  b r ] ; c r  ; [  c k ] ; b k  ] ] a c b |

45. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1045 TU/e Mixer realization Production rules: a r  c k  a k  b r  c k  b k   c k  a k   c k  b k  a r  b r  c r   a r   b r  c r  More symmetric production rules: a r  c k  a k  a r  c k  a k   a r   c k  a k   a r   c k  a k  premature a k  more expensive | a c b

46. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1046 TU/e Mixer realizations Mixer: area, delay, energy Area: 6 gate equivalents Delay per cycle: 8 gate delays Energy per cycle: 8 transitions

47. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1047 TU/e Assignment: duplicator realization Behavior:  [[a  : (b   ; b   ; b   ) ] ; [a  : b   ]] Required:realization with 2 sequential gates (sequencer + mixer requires 3 sequential gates) Follow all 8 realization steps!! Add comparison with sequencer+mixer realization. #2 a b

48. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1048 TU/e Duplicator chains Assume a M toggles at frequency f. Hence a 0 toggles at frequency f / 2 M. Let E dup be the duplication energy per cycle. Power of duplicator chain equals P = f E dup (1/2 + 1/4 + 1/8 +...) < f E dup

49. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1049 TU/e For those who are interested in the details Synthesis of Asynchronous VLSI Circuits –Alain J. Martin –Caltech CS-TR-93-28 –PostScript link via async.bib (html version) Programming in VLSI: From communicating processes to delay-insensitive circuits –Pages 1–64 in C.A.R. Hoare, ed., –Developments in Concurrency and Communication

50. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1050 TU/e General asynchronous background Principles of Asynchronous Circuit Design –Eds. Jens Sparsø and Steve Furber –Kluwer Academic Press, Dec. 2001 –ISBN 0-7923-7613-7 The ‘Asynchronous’ Bibliography –http://www.win.tue.nl/async-bib/ The Asynchronous Logic Home Page –http://www.cs.man.ac.uk/async/

51. Philips Research, Kees van Berkel, Ad Peeters, 2002-09-1051 TU/e Next week: lecture 3 Outline: Handshake components … and their realization as networks of gates Handshake circuits Initialization of handshake circuits