Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)1 The IEEE std for mixed-signal test J. M. Martins Ferreira FEUP / DEEC - Rua Dr. Roberto Frias Porto - PORTUGAL Tel / Fax: /

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)2 The std defines an extension to , 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) The IEEE standard for mixed signal test

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)3 IEEE : 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)5 TBIC: The switching structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)6 TBIC: Switching structure patterns Main testing conditions

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)7 Switching assignments for defined instructions (TBIC)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)8 TBIC: Control structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)10 ABMs: Switching structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)11 ABMs: Switching structure patterns (1) Main testing conditions for analog measurements

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)12 ABMs: Switching structure patterns (2) Normal mission mode; pin connected to core only.

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)13 ABMs: Switching pattern requirements

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)14 ABMs: Control structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)15 The register structure The register structure is entirely digital and identical to the corresponding structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)16 The PROBE instruction The IEEE 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)21 Interconnect testing with VHVH VLVL ? VHVH VLVL ?

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)22 Functional description of a basic “ component” The core circuitry is restricted to –A voltage follower –A logic inverter The required infrastructure should only support the mandatory instructions

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)23 Summary description of the 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)

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)25 “ component”: the digital test infrastructure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)26 Altera’s design environment (Max+plus II Baseline)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)27 Example description (ABM)

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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;

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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;

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)30 “ component”: the TBIC switching structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)31 “ component”: the ABMs switching structure

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)32 An “ component”: wire wrapping prototype

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)33 An “ 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)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)34 Proposed experiments: observability + controllability Two experiments will be demonstrated using the wire-wrapping “ 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)37 Observability test code (demo component) ! Observability demo using the 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)40 Video-demos: Observability and controllability (the wmv and bst files are stored in the hibu2k4\misc folder)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)41 The STA400 ( analog test access device) Features (from the data sheet): –Compliant to IEEE & –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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)42 STA400: Operating modes

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)43 STA400: Functional information CE/CEI distinguish between the two main operating modes (analog sample, mux / demux)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)44 STA400: TAP controller instructions

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)45 STA400: Scan chain sequence

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)46 STA400:Template to determine the BSR contents 1- Instruction 2- ABMs : Switches, switching pattern, control word 3- TBIC : Switches, switching pattern, control word 4- BS contents : Fill in the BS register bitstream

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)47 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)48 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

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)49 Schematic diagram +12V Iout 0V V A0 A1 A2 A3 AT1 AT2 A01 A23 TDITMSTCKTDO C0 C1 VCC CE /TRST CEI MODE GND A0 A1 A2 A3 AT2 AT1 TCK TMS TDO TDI GNDVCC 1Y31Y42Y12Y22Y32Y4 1Y31Y42Y12Y22Y32Y4 1Y11Y2 1A31A4 2A12A22A3 2A4 1A11A2 TCK TMS TDI TDO GND VCC /1OE/2OE 0V +5V 0V 24 +5V TDOTDI TMS TCK SN74BCT8244 DIP switches STA400 Prototyping area V

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)50 Demonstration board #2 Adjustable current source DIP switches that control the BCT8244 octal outputs SN74BCT8244 BST octal (TI SCOPE family) National Semiconductor SCANSTA400 Prototyping area: Connectors and space available for add-on boards TCK TDI TMS TDO JTAG port A0 A2 A1 A3 CE GND A23A01AT2AT1 +12V GND I out

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)51 Add-on boards

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)52 Experiment #1: Control A01 via the BCT8244 scan octal STA400BCT8244 TDI C01Y1 A0 A1 A01 s: sine p: pulseDIP switch TDO s/p

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)53 Experiment #1: Control A01 via 1Y1 (SVF code) Set 1Y1 to 0 (A01  A0 at EXTEST in BCT8244) STA400BCT8244 TDI C01Y1 A0 A1 A01 TDO s/p

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)54 A01 (STA400) 1Y1 (BCT8244)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)55 Experiment #2: Functional test (observe A0 at AT2) STA400BCT8244 TDI A0 A1 A01 s: sine p: pulseDIP switch TDO s/p AT2

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)56 Experiment #2 (observe A0 at AT2): SVF code ABM[A0]: SD + SB2 on TBIC: S6 + S9 on STA400BCT8244 TDI A0 A1 A01 TDO s/p AT2

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)57 AT2 (STA400)

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)58 Experiment #3: Parametric testing (R=?) STA400BCT8244 TDI A1 A01 DIP switch TDO AT2 AT1 A0 R=? Volt I + Amp

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)59 Experiment #3: Measuring R [A0-GND] (SVF code) STA400BCT8244 TDI A1 A01 AT2 AT1 A0 R=? Volt I + Amp ABM[A0]: SB1 + SB2 on TBIC: S5 + S6 on

Introduction to design for test techniques – The IEEE std for mixed-signal test © J. M. Martins Ferreira - University of Porto (FEUP / DEEC)60 (R to be measured is 1K2)