1. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)1 The IEEE 1149.4 std for mixed-signal test J. M. Martins Ferreira FEUP / DEEC - Rua Dr. Roberto Frias 4200-537 Porto - PORTUGAL Tel. 351 225 081 748 / Fax: 351 225 081 443 (jmf@fe.up.pt / http://www.fe.up.pt/~jmf)

2. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)2 The IEEE 1149.4 standard for mixed signal test The 1149.4 std defines an extension to 1149.1, to which it adds: –An analog test port (ATAP) with two pins (AT1, AT2) –An internal analog test bus (AB1, AB2) –A test bus interface circuit (TBIC) –The analog boundary modules (ABM)

3. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)3 IEEE 1149.4: The TBIC and the ABMs Interconnect and parametric tests can be carried out through the ABMs Analog test signals may be routed from / to the analog pins to / from the ATAP through the TBIC and the ABMs The TBIC and the ABM comprise a switching structure and a control structure

4. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)4 The test bus interface circuit (TBIC) The TBIC defines the interconnections between the ATAP (AT1 and AT2) and the internal analog test bus (at least two lines, AB1 and AB2) The TBIC comprises a switching structure and a control structure

5. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)5 TBIC: The switching structure

6. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)6 TBIC: Switching structure patterns Main testing conditions

7. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)7 Switching assignments for defined instructions (TBIC)

8. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)8 TBIC: Control structure

9. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)9 The analog boundary modules (ABM) The ABMs in the analog pins extend the test functions made available by the DBMs All test operations combine digital (via TAP) and analog test “vectors” (via ATAP) Each ABM comprises a switching structure and a control structure

10. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)10 ABMs: Switching structure

11. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)11 ABMs: Switching structure patterns (1) Main testing conditions for analog measurements

12. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)12 ABMs: Switching structure patterns (2) Normal mission mode; pin connected to core only.

13. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)13 ABMs: Switching pattern requirements

14. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)14 ABMs: Control structure

15. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)15 The 1149.4 register structure The 1149.4 register structure is entirely digital and identical to the corresponding 1149.1 structure

16. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)16 The PROBE instruction The IEEE 1149.4 std defines a fourth mandatory instruction called PROBE: –The selected data register is the BS register –One or both of the ATAP pins connect to the corresponding AB1/AB2 internal test bus lines –Analog pins connect to the core and to AB1/AB2 as defined by the ABM 4-bit control word –Each DBM operates in transparent mode

17. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)17 Analog test operations Principle of operation : –The analog signal is applied to AT1 and the analog response is observed in AT2 –With AT1 connected to AB1, the analog signal may be routed to the internal circuitry or to an analog output pin –Analog responses from the internal circuitry or from an analog input pin are routed to AB2, and observed in AT2

18. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)18 Observability of analog (input / output) pins The signal present at any analog (input / output) pin may be observed at AT2, with (or without) the core connected to the pin

19. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)19 Controllability of analog (input / output) pins The signal present at any analog (input / output) pin may be driven from AT1, regardless of the signal present at the analog input

20. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)20 Impedance measurement between pin and ground ITIT V VTVT Z D = V T / I T if: Z V >> Z S6 + Z SB2 Z V + Z S6 + Z SB2 >> Z D ZDZD

21. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)21 Interconnect testing with 1149.4 VHVH VLVL ? VHVH VLVL ?

22. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)22 Functional description of a basic “1149.4 component” The core circuitry is restricted to –A voltage follower –A logic inverter The required 1149.4 infrastructure should only support the mandatory instructions

23. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)23 Summary description of the 1149.4 infrastructure Instruction codes (8-bit): –EXTEST: $00 –SAMPLE / PRELOAD: $02 –PROBE: $01 –BYPASS: $FF Boundary scan register (TDI-TDO, 14-bit): –TBIC (4-bit), ABM analog input (4-bit), ABM analog output (4-bit), DBM digital input (1-bit), DBM digital output (1-bit)

24. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)24 Implementation details The digital test infrastructure and core logic was implemented by Dr. Gustavo Alves in an EPM7128 Altera PLD (2,500 usable gates, 128 macrocells, 84 pin PLCC) All remaining blocks are implemented using discrete components (ADG452 + MAX4512 analog switches, LM311 comparators, TL081 OpAmp)

25. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)25 “1149.4 component”: the digital test infrastructure

26. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)26 Altera’s design environment (Max+plus II Baseline)

27. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)27 Example description (ABM)

28. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)28 ABM: the control structure TITLE " ABM control register "; SUBDESIGN ABM_CR ( TDI, TCK, en_clkDR, shift, en_uptDR, pin_comp : INPUT; TDO, D, C, B1, B2 : OUTPUT; ) (...) IF ( !en_clkDR ) THEN DATA = DATA ; CONTROL = CONTROL ; BUS1 = BUS1 ; BUS2 = BUS2 ; ELSIF ( !shift ) THEN DATA = pin_comp; % Capture % CONTROL = GND; BUS1 = GND; BUS2 = GND; ELSE DATA = TDI; % Shift % CONTROL = DATA; BUS1 = CONTROL; BUS2 = BUS1; END IF; TDO = BUS2; IF ( !en_uptDR ) THEN D_LATCH = D_LATCH ; C_LATCH = C_LATCH ; B1_LATCH = B1_LATCH ; B2_LATCH = B2_LATCH ; ELSE D_LATCH = DATA; % SHIFT -> LATCH -- update % C_LATCH = CONTROL ; B1_LATCH = BUS1 ; B2_LATCH = BUS2 ; END IF; D = D_LATCH.q ; C = C_LATCH.q ; B1 = B1_LATCH.q ; B2 = B2_LATCH.q ; END;

29. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)29 ABM: the switching structure decoder BEGIN TABLE M1, M2, D, C, B1, B2 => SD, SH, SC, SG, SB1, SB2 ; 1,1,0,0,0,0 => 0,0,0,0,0,0 ; % p0 - Completely isolated (CD state) % 1,1,0,0,0,1 => 0,0,0,0,0,1 ; % p1 - Monitored by AB2 % 1,1,0,0,1,0 => 0,0,0,0,1,0 ; % p2 - Connected to AB1 % 1,1,0,0,1,1 => 0,0,0,0,1,1 ; % p3 - Connected to AB1; monitored by AB2 % (...) 1,1,1,1,1,1 => 0,1,0,0,1,1 ; % p15 - Connected to VH and AB1; monitored by AB2 % 0,1,0,0,0,0 => 1,0,0,0,0,0 ; % p16 - Connected to core; isolated from all test circuits % 0,1,0,0,0,1 => 1,0,0,0,0,1 ; % p17 - Connected to core; monitored by AB2 % 0,1,0,0,1,0 => 1,0,0,0,1,0 ; % p18 - Connected to core and AB1 % 0,1,0,0,1,1 => 1,0,0,0,1,1 ; % p19 - Connected to core and AB1; monitored by AB2 % 0,1,1,X,X,X => 1,0,0,0,0,0 ; % p16 - Clause 6 - page 74 % 0,1,X,1,X,X => 1,0,0,0,0,0 ; % p16 - Clause 6 - page 74 % 0,0,X,X,X,X => 1,0,0,0,0,0 ; % p16 - Clause 4 - page 74 % 1,0,X,X,X,X => 0,0,0,0,0,0 ; % p0 - Clause 3 - page 74 % END TABLE;

30. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)30 “1149.4 component”: the TBIC switching structure

31. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)31 “1149.4 component”: the ABMs switching structure

32. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)32 An “1149.4 component”: wire wrapping prototype

33. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)33 An “1149.4 component”: printed circuit board Notes : 1) The ABM comparator inputs in this board differ from the standard (V TH is connected to the + input). 2) V G / V TH may be applied externally (internal value of V G is 0 V) Selection of V TH (internal / external) Selection of V G (internal / external)

34. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)34 Proposed experiments: observability + controllability Two experiments will be demonstrated using the wire-wrapping “1149.4 component”: –The waveform at the analog output pin will be observed at AT2, when the analog input is driven by a sine wave –The waveform at the analog output pin will be driven from AT1 (a square wave), instead of the sine wave coming from the internal circuitry

35. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)35 Observing an analog input / output pin at AT2 PROBE is the current instruction, the input ABM connects the pin to the core, the output ABM connects the pin to the core and to AB2, AB2 is connected to AT2

36. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)36 Observability test code segment Recommendation: Write the JTAGer test segment enabling the observability of the analog output as shown at right AN_IN AN_OUT AT1 AT2 AN_IN AN_OUT AT1 AT2

37. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)37 Observability test code (demo component) ! Observability demo using the 1149.4 component start: seltap0; rst; stateirshift; ldcnt,8d; ! IR has 8 bits nshfcp40h,80h,C0h; ! Instr. S/P and infra-structure check jerrtap-error; ! Abort test in case of TAP error statedrshift; ldcnt,14d; ! 4 TBIC + 2x4 ABMs + 1 DBM + 1 DBM nshf2020h; ! 0001(TBIC)- 0000(ABMin)- 0001(ABMout)- 00(DBMs) stateirshift; ldcnt,8d; nshf80h; ! Instr. PROBE tms1; ! Update-IR end: halt; ! Stop here if everything is OK tap-error: halt; ! Stop here if the TAP is faulty << Breakpoint Before the breakpoint After the breakpoint

38. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)38 Controlling an analog output pin from AT1 EXTEST is the current instruction, the input ABM disconnects the pin from the core, the output ABM disconnects the pin from the core and connects it to AB1, AB1 connects to AT1

39. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)39 Controllability test code segment Recommendation: Write the JTAGer test segment enabling the controllability (plus observability) of the analog output as shown at right AN_IN AN_OUT AT1 AT2 AN_IN AN_OUT AT1 AT2

40. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)40 The SCAN STA400 (1149.4 analog test access device) Features (from the data sheet): –Compliant to IEEE 1149.1 and 1149.4 –Analog mux / demux either dual 2:1 or single 4:1 –Samples up to 9 analog test points –Includes CLAMP and HIGHZ instructions –TRST input –Input range from -0,5 V to +6,5 V

41. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)41 SCAN STA400: Operating modes

42. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)42 SCAN STA400: Functional information CE/CEI distinguish between the two main operating modes (analog sample, mux / demux)

43. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)43 SCAN STA400:Template to determine the BSR contents 1- Instruction 2- ABMs : switches, switching pattern, control word 3- TBIC : switches, switching pattern, control word

44. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)44 Demonstration board #1: Stand-alone STA400 A AT1 The built-in current source is adjustable JTAGer- compatible TAP connections ATAP connections +12 V / GND power supply SCANSTA400 analog I/O pins Notes : 1) The internal 7805 generates the +5 V power supply 2) The operating mode is selected via a set of built-in jumpers 0 CEI 1 CE 0 C1 0 C0 0 M  is 0,  is 1

45. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)45 Demonstration board #2: STA400 and BCT8244 The STA400 and the BCT8244 are in the same chain The BCT8244 is able to control the STA400 Parametric and functional tests are possible

46. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)46 Schematic diagram

47. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)47 Demonstration board #2 Adjustable current source DIP switches that control the BCT8244 octal outputs SN74BCT8244 BST octal (TI SCOPE family) National Semiconductor SCANSTA400 Connectors and space available for add-on boards

48. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)48 Add-on boards

49. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)49 Experiment #1: Control A01 via the BCT8244 scan octal STA400BCT8244 TDI C01Y1 A0 A1 A01 s: sine p: pulseDIP switch TDO s/p

50. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)50 Experiment #2: Functional test (observe A0 at AT2) STA400BCT8244 TDI A0 A1 A01 s: sine p: pulseDIP switch TDO s/p AT2

51. Leonardo da Vinci ALLEGRO © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)51 Experiment #3: Parametric testing (R=?) STA400BCT8244 TDI A1 A01 DIP switch TDO AT2 (read V) AT1 (drive I) A0 R=?