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US 8,020,059 B2Granted
Tap and control with data I/O, TMS, TDI, and TDO
AssigneeTexas Instruments Incorporated
InventorLee D. Whetsel
Life of this patent
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Abstract
An optimized JTAG interface is used to access JTAG Tap Domains within an integrated circuit. The interface requires fewer pins than the conventional JTAG interface and is thus more applicable than conventional JTAG interfaces on an integrated circuit where the availability of pins is limited. The interface may be used for a variety of serial communication operations such as, but not limited to, serial communication related integrated circuit test, emulation, debug, and/or trace operations.
Claims5
An integrated circuit, comprising:
- A. tap domain test access port circuitry having a test data in (TDI) input lead, a test mode select (TMS) input lead, a test clock (TCK) input lead, and a test data out (TDO) output lead;
- and
- B. serial to parallel control circuitry having a data input/output lead, and a clock input lead, the control circuitry being connected to the test access port circuitry by a TDI output lead coupled to the TDI input lead, a TMS output lead coupled to the TMS input lead, a TCK output lead coupled to the TCK input lead, and a TDO input lead coupled to the TDO output lead, the serial to parallel control circuitry including:
- i. input/output circuitry having a lead connected to the data input/output lead, a TMS/TDI input lead, and a lead connected to the TDO input lead;
- ii. serial input parallel output circuitry having a serial input connected to the TMS/TDI input lead, a clock input connected with the clock input lead, a TDI output, and a TMS output;
- and
- iii. update register circuitry having a first input connected to the TDI output of the serial input parallel output circuitry and a first output connected to the TDI output lead, having a second input connected to the TMS output of the serial input parallel output circuitry and a second output connected to the TMS output lead, and having an update clock input.
4 more elements
Dependencies are inferred from the claim text.