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US 8,412,995 B2Granted
TAP and AUX with IR control of TDI input multiplexer
AssigneeTexas Instrument Incorporated
InventorLee D. Whetsel
Life of this patent
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Abstract
The present disclosure describes novel methods and apparatuses for directly accessing JTAG Tap domains that exist in a scan path of many serially connected JTAG Tap domains. Direct scan access to a selected Tap domain by a JTAG controller is achieved using auxiliary digital or analog terminals associated with the Tap domain and connected to the JTAG controller. During direct scan access, the auxiliary digital or analog terminals serve as serial data input and serial data output paths between the selected Tap domain and the JTAG controller.
Claims5
An integrated circuit comprising:
- A. a serial instruction register having a serial data input coupled to a test data input, a serial data output, an instruction register control bus output, and a control bus input;
- B. a serial data register having a serial data input coupled to the test data input, a serial data output, and a control input connected to the instruction register control bus output;
- C. first multiplexer circuitry coupling the serial data output of the instruction register and the serial data output of the data register to a test data output, and having a control input;
- D. TAP control circuitry having a clock input connected to a test clock input, a mode select input connected to a test mode select input, and a TAP control bus output connected to the control bus input of the instruction register and the control input of the multiplexer circuitry;
- E. auxiliary circuitry connected to the serial instruction register, the TAP control circuitry, the test data input, the test data output, and an auxiliary input lead;
- F. second multiplexer circuitry having an input connected with the test data input, an input connected with the auxiliary input lead, a control input, and an output connected with the serial data input of the serial instruction register and the serial data register;
- and
- G. the serial instruction register having a control output connected to the control input of the second multiplexer.
5 more elements
Dependencies are inferred from the claim text.