Abstract
An IC includes an IEEE 1149.1 standard test access port (TAP) interface and an additional Off-Chip TAP interface. The Off-Chip TAP interface connects to the TAP of another IC. The Off Chip TAP interface can be selected by a TAP Linking Module on the IC.
Claims
1. An integrated circuit comprising: A. a substrate; B. a TDI input pad, a TCK input pad, a TMS input pad, and a TDO output pad, all formed on the substrate; C. an IC TAP domain formed on the substrate, the IC TAP domain having an IC TDI input lead, an IC TCK input lead, an IC TMS input lead, and an IC TDO output lead; D. a core TAP domain formed on the substrate, the core TAP domain having a core TDI input lead, a core TCK input lead, a core TMS input lead, and a core TDO output lead; E. an off-chip TAP interface formed on the substrate, the off-chip TAP interface having an interface TDI input lead, an off-chip TDO output lead coupled to the interface TDI input lead, an interface TCK input lead, an off-chip TCK output lead coupled to the interface TCK input lead, an interface TMS input lead, an off-chip TMS output lead coupled to the interface TMS input lead, an interface TDO output lead, and an off-chip TDI input lead coupled to the interface TDO output lead; F. input linking circuitry formed on the substrate, the input linking circuitry coupling the TDI input pad to one of the IC TDI input lead, the core TDI input lead, and the interface TDI input lead, and the input linking circuitry coupling the TMS input pad to the TMS input lead of the selected IC TAP domain, the core TAP domain, and the TAP interface in response to control signals on control input leads; G. output linking circuitry formed on the substrate, the output linking circuitry selectively coupling one of the IC TDO output lead, the core TDO output lead, and the interface TDO output lead to the TDO output pad in response to control signals on control input leads; and H linking control circuitry formed on the substrate and connected in series between the TDI input pad and the TDO output pad, the linking control circuitry including an instruction register having a TDI input coupled to the TDI input pad, control output leads connected to the control input leads of the input linking circuitry and the output linking circuitry, and an output, a multiplexer having a TDI input coupled to the TDI input pad, a register input coupled to the output of the instruction register, and an output, and a buffer having an input coupled to the output of the multiplexer and an output coupled to the TDO output pad.
2. The integrated circuit of claim 1 in which the IC TAP domain includes boundary scan circuitry coupled to I/O circuitry.
3. The integrated circuit of claim 1 in which the IC TAP domain includes boundary scan circuitry coupled to I/O circuitry, and the core TAP domain includes core circuitry separate from the I/O circuitry and the IC TAP domain.
4. The integrated circuit of claim 1 in which the off-chip TAP interface includes circuitry separate from the IC TAP domain and the core TAP domain.
5. The integrated circuit of claim 1 in which the linking control circuitry is connected between the TDI input pad and the input linking circuitry.
6. The integrated circuit of claim 1 in which the linking control circuitry is connected between the output linking circuitry and the TDO output pad.
7. The integrated circuit of claim 1 in which the input linking circuitry includes multiplexer circuitry having inputs connected to the TDI input pad, the IC TDO output lead, the core TDO output lead, and the interface TDO output lead, and having an output coupled to the IC TDI input lead, an output coupled to the core TDI input lead, and an output coupled to the interface TDI input lead.
8. The integrated circuit of claim 1 in which the input linking circuitry includes gating circuitry selectively connecting the first TMS input pad to each of the TAP domain, the core TAP domain, and the TAP interface.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) FIG. 1A illustrates a conventional art IEEE 1149.1 (JTAG) architecture as it could be implemented within an IC or core circuit.
(2) FIG. 1B illustrates the conventional art substrate of an IC or core circuit including the JTAG architecture and interface.
(3) FIG. 1C illustrates a conventional art JTAG accessible internal scan path coupled to logic circuitry.
(4) FIG. 1D illustrates a conventional art JTAG accessible in-circuit emulation register coupled to emulation circuitry.
(5) FIG. 1E illustrates a conventional art JTAG accessible in-system programming register coupled to in-system programming circuitry.
(6) FIG. 1F illustrates a conventional art JTAG accessible boundary scan register coupled to input and output circuitry.
(7) FIG. 2 illustrates the conventional art state diagram of the JTAG TAP controller.
(8) FIG. 3 illustrates an IC containing conventional art TAP domains daisy-chained between the ICs TDI and TDO pins.
(9) FIG. 4 illustrates a conventional art TAP Linking Module (TLM) Architecture implemented within an IC.
(10) FIG. 5 illustrates conventional art TMS gating circuitry that could be used in the input linking circuitry of the FIG. 4 TLM architecture.
(11) FIG. 6 illustrates conventional art TDI multiplexing circuitry that could be used in the input linking circuitry of the FIG. 4 TLM architecture.
(12) FIG. 7 illustrates conventional art TDO multiplexing circuitry that could be used in the output linking circuitry of the FIG. 4 TLM architecture.
(13) FIG. 8A illustrates conventional art TLM circuitry that could be used in the FIG. 4 TLM architecture.
(14) FIG. 8B illustrates an instruction register that could be used in the conventional art TLM circuitry of FIG. 8A.
(15) FIG. 9 illustrates some possible conventional art TAP domain linking arrangements of the TLM architecture of FIG. 4 as they would appear during JTAG instruction scan operations.
(16) FIG. 10 illustrates the conventional art TAP domain linking arrangements of FIG. 9 as they would appear during JTAG data scan operations.
(17) FIG. 11A illustrates the TLM architecture of FIG. 4 improved to include the Off-Chip TAP (OCT) interface of the present invention.
(18) FIG. 11B illustrates the OCT interface being coupled to the JTAG interface of another IC/die.
(19) FIG. 12 illustrates the TMS gating circuitry of FIG. 5 including an additional TMS gate for controlling access to the OCT interface.
(20) FIG. 13 illustrates the TDI multiplexing circuitry of FIG. 6 including an additional TDI multiplexer for input to OCT interface and the other multiplexers being equipped with an additional input for receiving TDO input from the OCT interface.
(21) FIG. 14 illustrates the TDO multiplexer circuitry of FIG. 7 being equipped with an additional input for receiving the TDO output from the OCT interface.
(22) FIG. 15 illustrates some possible TAP domain linking arrangements from the TLM architecture of FIG. 11A as they would appear during JTAG instruction scan operations.
(23) FIG. 16 illustrates the TAP domain linking arrangements of FIG. 14 as they would appear during JTAG data scan operations.
(24) FIGS. 17A-17O illustrate various TAP domain link arrangements between two Die on a substrate, each Die including the improved TLM architecture of FIG. 11A.
(25) FIG. 18 illustrates a more complex arrangement of Die on substrate, each Die including the improved TLM architecture of FIG. 11A.
(26) FIG. 19 illustrates two substrates serially daisy-chained to a JTAG controller, each substrate including two Die each implementing the improved TLM architecture of FIG. 11A.
(27) FIG. 20 illustrates the improved TLM architecture whereby the position of the TLM circuit is moved such that it exists on the serial path next to the IC's TDI input pin instead of on the serial path next to the IC's TDO pin as illustrated in FIG. 11A.
(28) FIG. 21 illustrates a functional IC that includes the conventional JTAG port interface and the OCT interface of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
(29) FIG. 11A illustrates the improvement to the TLM architecture of FIG. 4. The improvement is the addition of an Off-Chip Tap (OCT) interface 1106. The OCT interface can be selected between the ICs TDI and TDO pins, via the TLM's TAP Link Control bus, exactly as the IC and core TAP domains were described being selected. Once selected, the OCT interface can serve as a master TAP interface to a slave TAP interface (i.e. a conventional 1149.1 TAP interface) on another IC. Thus an IC having the TLM architecture improvement shown in FIG. 11A would have the conventional 1149.1 TAP interface 1102 plus the selectable OCT interface 1106 for mastering the TAP interface of another IC or ICs 1108. While one OCT interface 1106 is shown in FIG. 11A, any number of OCT interfaces may be provided.
(30) FIG. 11B illustrates the OCT interface 1106 being coupled 1110 to a TAP interface of another IC 1108. As seen in FIG. 11B, the OCT interface consists of buffers which couple the TDI.sub.OCT, TCK, TMS.sub.OCT, TDO.sub.OCT, and TRST TLM architecture signals up to TDO, TCK, TMS, TDI, and TRST pads 1104, respectively, of the IC in which the TLM architecture resides. The TDO, TCK, TMS, TDI and TRST pads 1104 can be coupled to the TDI, TCK, TMS, TDO and TRST pads of the other IC 1108, via connections 1110, to provide access the TAP domain of the other IC 1108. The TAP domain of the other IC could be similar to that shown in FIG. 1A.
(31) FIGS. 12-14 illustrate the changes required to the Input and Output linking circuitry of FIGS. 5-7, respectively, to add the OCT interface of FIG. 11A. As seen in FIG. 12, an additional AND gate 1202 is added to provide gating on and off the TMS input (TMS.sub.OCT) of the OCT interface. As seen in FIG. 13, an additional multiplexer 1302 is provided for selecting the TDI input (TDI.sub.OCT) of the OCT interface, and the other multiplexers are provided with an additional input for receiving the TDO output (TDO.sub.OCT) of the OCT interface. As seen in FIG. 14, an input is added to the output multiplexer to receive the TDO output (TDO.sub.OCT) of the OCT. Additionally, control signals are added to the TLM's TAP Link Control bus to provide for controlling the added TMS.sub.OCT AND gate, the additional TDI.sub.OCT multiplexer, and the additional TDO.sub.OCT input to the multiplexers.
(32) FIG. 15 illustrates examples of the possible TAP Link arrangements (Link0-Link13) of the TLM architecture of FIG. 11A during TAP instruction register scan operations. The link arrangements include those previously shown in FIG. 9, plus additional link arrangements that include the OCT interface. As seen, there are two powerup/reset options for the default TAP link, Link0 and Link7. The Link0 (option 1) selects only the IC's TAP in the link, whereas Link7 (option 2) selects the IC's TAP plus the OCT interface in the link. An example of why option 2 may be necessary is shown in example F of FIG. 17.
(33) FIG. 16 is provided to simply show, as did FIG. 9, that the TLM is transparent during TAP data register scan operations.
(34) FIGS. 17A-17O show examples of various TAP Link arrangements between two die (Die 1 and 2) located on a common substrate. While each Die 1 and 2 is shown including the improved TLM architecture (TLMA) of FIG. 16 it should be understood that only Die 1 of each example requires the TLM architecture of FIG. 16 to provide access to Die 2. Die 2 of each example could simply have a JTAG architecture as shown in FIG. 1A. In each example, the conventional TAP interface 1702 of Die 1 (TDI, TCK, TMS, TRST, and TDO) is the TLMA interface of Die 1 and is coupled to a JTAG bus controller, such as a tester, debugger, emulator, or other controller. Also in each example, the OCT interface 1704 of Die 1 (TDI, TCK, TMS, TRST and TDI) is coupled to the conventional TAP interface 1706 of Die 2 (TDI, TCK, TMS, TRST and TDI) which is the TLMA interface of Die 2.
(35) In example A, only the IC TAP of Die 1 is included in the link to the JTAG controller. In example B, only the Core N TAP is included in the link to the JTAG controller. In example C, only the Core 1 TAP is included in the link to the JTAG controller. In example D, the Core 1 and Core N TAPs are included in the link to the JTAG controller. In example E, all TAPs of Die 1 are included in the Link to the JTAG controller.
(36) In example F, the IC TAPs of Die 1 and 2 are included in the Link to the JTAG controller, the IC TAP of Die 2 being accessed via the OCT interface of Die 1. The Link of Example F would be selected to allow performing JTAG Extest interconnect testing on both Die 1 and Die 2. As mentioned in regard to option 2 of FIG. 16, the link arrangement of example F may be selected as the powerup/reset link to allow the IC TAPs of both Die 1 and 2 to be accessed for interconnect testing.
(37) In example G, the TAPs of Die 1 are all bypassed while the IC TAP of Die 2 is included in the link to the JTAG controller via the OCT of Die 1. In this arrangement, the TAP link of Die 1 would be as shown in Link13 of FIGS. 15 and 16. Examples H through L similarly bypass the Die 1 TAPs to access the TAPs of Die 2 via the OCT. Example M through O illustrates various links that include TAPs of both Die 1 and Die 2. Examples L and O illustrate that the OCT of Die 2 could be used if necessary to link to TAP interfaces of other Die.
(38) FIG. 18 illustrates an example of a more complex Die on Substrate arrangement whereby the flexibility of the improved TLM architecture can be further seen. The TLMA interface 1802 of Die 1 serves as the Die coupled to the JTAG controller, as it did in the previous examples. Die 1 also serves as the TAP access point, via its OCT 1804, to daisy-chained TLMA interfaces 1806 and 1808 of Die 2 and 3. Die 2 and Die 3 serve as further TAP access points, via their OCTs 1810 and 1812, to TLMAs 1814 and 1816 of Die 4 and 5, respectively. By dotted line arrows it is seen that any one or more TAP domains of each Die 1-5 may be selected and linked for access via the JTAG controller connection to Die 1. Further, bypassing of Die 1, as in examples G through L allows direct access to Die 2 and 3. Die 2 and 3 can be similarly bypassed to provide direct access to Die 4 and 5.
(39) FIG. 19 illustrates two substrates 1902 and 1904 each with two die that include the improved TLM architecture of FIG. 11A. Substrate 1902 includes a die labeled Die 1:1 and a die labeled Die 1:2. Substrate 1904 includes a die labeled Die 2:1 and a die labeled Die 2:2. The TLMA interface 1906 of Die 1:1 is daisy-chained with the TLMA interface 1914 of Die 2:1. The daisy-chained path is coupled to a JTAG controller. The TLMA interface 1910 of Die 1:2 is coupled to the OCT interface 1908 of Die 1:1. The TLMA interface 1918 of Die 2:2 is coupled to the OCT interface 1916 of Die 2:1. The importance of FIG. 19 is the showing of a serial access approach whereby the JTAG controller may access TAP domains vertically as well as horizontally. The Die labeling is done such that the left number indicates the horizontal position of the Die's substrate on the daisy-chained path and the right number indicates the vertical position of the Die on the substrate.
(40) In a first example, the JTAG controller may horizontally access TAP domains of only Die 1:1 and 2:1 in the daisy-chain arrangement without accessing the TAP domain of vertically accessible Die 1:2 and 2:2. In a second example, the JTAG controller may vertically access the TAP domains of Die 1:2, via the OCT of Die 1:1, and include those TAP domains in with the daisy-chained horizontal access of TAP domains in Die 1:1 and 2:1. In a third example, the JTAG controller may vertically access the TAP domains of Die 1:2 via the OCT of Die 1:1, the TAP domains of Die 2:2 via the OCT of Die 2:1, and include those TAP domains in with the daisy-chained horizontal access of TAP domains in Die 1:1 and 2:1. In a forth example, the JTAG controller may bypass (as shown in FIGS. 17J-17I) the TAP domains of Die 1:1 and 2:1 to vertically access the TAP domains of Die 1:2 and 2:2 such that only the TAP domains of Die 1:2 and 2:2 are included in the horizontal daisy-chain path to the JTAG controller. As can be seen, access to additional vertical Die is possible using the OCT interfaces 1912 and 1920 of Die 1:2 and 2:2.
(41) FIG. 20 is provided to indicate that the TLM can be positioned at the beginning of the IC's TDI to TDO serial path instead of at the ending as shown in FIG. 11A, if desired. The TLM circuit would operate as previously described to control the input and output linking circuitry. The only difference would be that the TLM's instruction shift register would no longer need to capture the JTAG required 0 and 1 bits shown in FIG. 8B, since those 0 and 1 bits would be provided during instruction scan operations to the IC's TDO by the selected TAP domain(s) instruction register. The leading position of the TLM in FIG. 19 would alter the TAP link arrangement examples of FIGS. 15 and 16 to the extent that the TLM would be shown existing at the beginning of the linked TAP domains (i.e. closes to the TDI pin) instead of at the ending of the linked TAP domains (i.e. closes to the TDO pin).
(42) FIG. 21 illustrates an IC including the present invention. The IC has functional inputs and outputs and functional circuitry responsive thereto. The IC has a conventional primary JTAG port (i.e. TLMA interface of the present invention) and a secondary JTAG port (i.e. OCT interface of the present invention). While a detail description has been given of how the TLM architecture can be improved to include the secondary JTAG port (OCT) of FIG. 21, there may be alternative/derivative approaches that could be envisioned to couple a primary JTAG port of a functional IC to a secondary port of the same functional IC. These other approaches would be inspired by the teachings provided by the present invention. To the extent that the present invention has provided an original teaching of at least one preferred way of doing this, the invention deserves claims that would broadly cover a functional IC that includes a conventional primary JTAG port for coupling to a JTAG controller and a secondary JTAG port for coupling to another primary JTAG port of another IC.
