| 摘要 |
A 1149.1 TAP performs at-speed Update & Capture, Shift & Capture and Back to Back Capture & Shift operations. In a first embodiment the at-speed operations are achieved by time division multiplexing CMD signals onto the TMS input to the TAP. In a second embodiment the at-speed operations are achieved by detecting the TAP's Exit1DR state as a CMD signal. In a third embodiment the at-speed operations are achieved by detecting the TAP's Exit1DR and PauseDR states. In a fourth embodiment the at-speed operations are achieved by detecting the TAP's Exit1DR and PauseDR states and inputting these states to a Dual Port Router to control the at-speed operations of a circuit. The improvements are achieved without requiring any additional IC pins beyond the 4 required TAP pins. Devices including the TAP improvements can be operated compliantly in a daisy-chain arrangement with devices that don't include the TAP improvements. |
