Technique for preconditioning I/Os during reconfiguration
First Claim
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1. A method for reconfiguring a programmable integrated circuit comprising:
- providing a user-selected input to the programmable integrated circuit;
driving a pad with the user-selected input when the programmable integrated circuit is being reconfigured, wherein the user-selected input is coupled to a first input of a multiplexer and a data path signal is coupled to a second input of the multiplexer, wherein an output of the multiplexer is coupled to the pad and a control node of the multiplexer is coupled to be controlled by a signal indicating whether the programmable integrated circuit is being reconfigured; and
reconfiguring the programmable integrated circuit.
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Abstract
A technique for configuring programmable integrated circuits. The technique involves preconditioning or predefining the outputs and I/Os of a programmable integrated circuit before the device is programmed or reconfigured. When the device is programmed, the outputs and I/Os of the programmable integrated circuit will be driven to the preconditioned or predefined states. The technique may be implemented in conformance with the IEEE 1149.1 boundary scan architecture standard. Standard IEEE 1149.1 instructions may be used. The technique may also be used during in-system programming of programmable integrated circuits.
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Citations
20 Claims
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1. A method for reconfiguring a programmable integrated circuit comprising:
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providing a user-selected input to the programmable integrated circuit; driving a pad with the user-selected input when the programmable integrated circuit is being reconfigured, wherein the user-selected input is coupled to a first input of a multiplexer and a data path signal is coupled to a second input of the multiplexer, wherein an output of the multiplexer is coupled to the pad and a control node of the multiplexer is coupled to be controlled by a signal indicating whether the programmable integrated circuit is being reconfigured; and reconfiguring the programmable integrated circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of reconfiguring a programmable integrated circuit comprising:
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transferring a first signal stored in a first register from the first register to a third register in response to an update signal; transferring a second signal stored in a second register from the second register to a fourth register in response to the update signal; controlling a control node of a tristate buffer with the second signal from the fourth register when the programmable integrated circuit is in a reconfigure mode; and transferring the first signal to the tristate buffer when the programmable integrated circuit is in the reconfigure mode, wherein the first signal is driven through the tristate buffer to a pad when the second signal enables the tristate buffer, and the pad is in a high-impedance state when the second signal-disables the tristate buffer. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A circuit apparatus for a programmable integrated circuit comprising:
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a pad; a tristate buffer, coupled to the pad; a first multiplexer, coupled through the tristate buffer to the pad, wherein the first multiplexer selects between a data path input and a user-selected data path input; a second multiplexer, coupled to a control node of the tristate buffer, wherein the second multiplexer selects between a tristate path input and a user-selected tristate path input; and a reconfiguration signal, coupled to the first multiplexer and the second multiplexer, for indicating when the programmable integrated circuit is in a reconfigure mode, wherein during the reconfigure mode, the first multiplexer couples the user-selected data path input to the tristate buffer and the second multiplexer couples the user-selected tristate path input to the control node of the tristate buffer. - View Dependent Claims (17, 18, 19, 20)
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Specification