Cypress CY7C1266V18, CY7C1270V18, CY7C1268V18, CY7C1277V18 manual Idcode

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CY7C1266V18, CY7C1277V18 CY7C1268V18, CY7C1270V18

IDCODE

The IDCODE instruction loads a vendor-specific, 32-bit code into the instruction register. It also places the instruction register between the TDI and TDO pins and shifts the IDCODE out of the device when the TAP controller enters the Shift-DR state. The IDCODE instruction is loaded into the instruction register upon power up or whenever the TAP controller is in a Test-Logic-Reset state.

SAMPLE Z

The SAMPLE Z instruction connects the boundary scan register between the TDI and TDO pins when the TAP controller is in a Shift-DR state. The SAMPLE Z command puts the output bus into a High-Z state until the next command is issued during the Update-IR state.

SAMPLE/PRELOAD

SAMPLE/PRELOAD is a 1149.1 mandatory instruction. When the SAMPLE/PRELOAD instructions are loaded into the instruction register and the TAP controller is in the Capture-DR state, a snapshot of data on the inputs and output pins is captured in the boundary scan register.

Be aware that the TAP controller clock can only operate at a frequency up to 20 MHz, although the SRAM clock operates more than an order of magnitude faster. Because there is a large difference in the clock frequencies, it is possible that during the Capture-DR state, an input or output may undergo a transition. The TAP may then try to capture a signal while in transition (metastable state). This does not harm the device, but there is no guarantee as to the value that is captured. Repeatable results may not be possible.

To guarantee that the boundary scan register captures the correct value of a signal, the SRAM signal must be stabilized long enough to meet the TAP controller's capture setup plus hold times (tCS and tCH). The SRAM clock input might not be captured correctly if there is no way in a design to stop (or slow) the clock during a SAMPLE/PRELOAD instruction. If this is an issue, it is still possible to capture all other signals and simply ignore the value of the CK and CK captured in the boundary scan register.

After the data is captured, it is possible to shift out the data by putting the TAP into the Shift-DR state. This places the boundary scan register between the TDI and TDO pins.

PRELOAD places an initial data pattern at the latched parallel outputs of the boundary scan register cells before the selection of another boundary scan test operation.

The shifting of data for the SAMPLE and PRELOAD phases can occur concurrently when required — that is, while data captured is shifted out, the preloaded data can be shifted in.

BYPASS

When the BYPASS instruction is loaded in the instruction register and the TAP is placed in a Shift-DR state, the bypass register is placed between the TDI and TDO pins. The advantage of the BYPASS instruction is that it shortens the boundary scan path when multiple devices are connected together on a board.

EXTEST

The EXTEST instruction drives the preloaded data out through the system output pins. This instruction also connects the boundary scan register for serial access between the TDI and TDO in the Shift-DR controller state.

EXTEST Output Bus Tri-State

IEEE Standard 1149.1 mandates that the TAP controller be able to put the output bus into a tri-state mode.

The boundary scan register has a special bit located at bit #108. When this scan cell, called the “extest output bus tri-state,” is latched into the preload register during the Update-DR state in the TAP controller, it directly controls the state of the output (Q-bus) pins, when the EXTEST is entered as the current instruction. When HIGH, it enables the output buffers to drive the output bus. When LOW, this bit places the output bus into a High-Z condition.

This bit can be set by entering the SAMPLE/PRELOAD or EXTEST command, and then shifting the desired bit into that cell, during the Shift-DR state. During Update-DR, the value loaded into that shift-register cell latches into the preload register. When the EXTEST instruction is entered, this bit directly controls the output Q-bus pins. Note that this bit is preset HIGH to enable the output when the device is powered up, and also when the TAP controller is in the Test-Logic-Reset state.

Reserved

These instructions are not implemented but are reserved for future use. Do not use these instructions.

Document Number: 001-06347 Rev. *D

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Contents Configurations FeaturesFunctional Description Selection GuideLogic Block Diagram CY7C1277V18 Logic Block Diagram CY7C1266V18Logic Block Diagram CY7C1270V18 Logic Block Diagram CY7C1268V18CY7C1266V18 4M x Pin ConfigurationsCY7C1277V18 4M x TMS TDICY7C1270V18 1M x CY7C1268V18 2M xQvld BWSPin Name Pin Description Pin DefinitionsSynchronous Read/Write Input. When Negative Input Clock InputPower Supply Inputs for the Outputs of the Device Power Supply Inputs to the Core of the DeviceTDO for Jtag TCK Pin for JtagFunctional Overview Application Example Delay Lock Loop DLLTruth Table OperationComments Write Cycle DescriptionsRemains unaltered During the data portion of a write sequenceInto the device Write cycle description table for CY7C1270V18 follows.2Written into the device. D 359 remains unaltered Into the device. D 80 and D 3518 remain unalteredIeee 1149.1 Serial Boundary Scan Jtag Idcode State diagram for the TAP controller follows.9 TAP Controller State DiagramTAP Electrical Characteristics TAP Controller Block DiagramParameter Description Test Conditions Min Max Unit GND ≤ VI ≤ VDDTAP Timing and Test Conditions TAP AC Switching CharacteristicsScan Register Sizes Identification Register DefinitionsInstruction Codes Register Name Bit SizeBit # Bump ID Boundary Scan OrderPower Up Sequence Power Up Sequence in DDR-II+ SramPower Up Waveforms DLL ConstraintsDC Electrical Characteristics Electrical CharacteristicsMaximum Ratings Operating RangeThermal Resistance20 Capacitance20AC Test Loads and Waveforms Parameter Description Test Conditions Max UnitParameter Min Max Switching CharacteristicsHigh LOWRead/Write/Deselect Sequence29 Switching WaveformsNOP Ordering Information 333 Ball Fbga 15 x 17 x 1.40 mm Package DiagramDocument History ECN No Issue Date Orig. Description of ChangeNXR VKN
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