Cypress CY7C1546V18, CY7C1548V18, CY7C1550V18, CY7C1557V18 manual Idcode

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CY7C1546V18, CY7C1557V18 CY7C1548V18, CY7C1550V18

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 at power up or whenever the TAP controller is supplied 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 supplied 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 input and output pins is captured in the boundary scan register.

The user must be aware that the TAP controller clock can only operate at a frequency up to 20 MHz, while 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 undergoes 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.

Once 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 the 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 pre-set 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: 001-06550 Rev. *E

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Contents Configurations FeaturesFunctional Description Selection GuideLogic Block Diagram CY7C1557V18 Logic Block Diagram CY7C1546V18Logic Block Diagram CY7C1550V18 Logic Block Diagram CY7C1548V18Ball Fbga 15 x 17 x 1.4 mm Pinout Pin ConfigurationCY7C1546V18 8M x CY7C1557V18 8M xCY7C1550V18 2M x CY7C1548V18 4M xPin Name Pin Description Pin DefinitionsBWS BWS2, BWS3 Synchronous Read or Write Input. WhenPower 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 Valid Data Indicator QvldEcho Clocks SRAM#1 SRAM#2Operation Write Cycle DescriptionsBWS0 BWS1 CommentsBWS0 BWS1 BWS2 BWS3 BWS0Ieee 1149.1 Serial Boundary Scan Jtag Idcode State diagram for the TAP controller follows TAP Controller State DiagramTAP Electrical Characteristics TAP Controller Block DiagramTDI TCKTAP Timing and Test Conditions TAP AC Switching CharacteristicsScan Register Sizes Identification Register DefinitionsInstruction Codes Register Name Bit SizeBit Number Bump ID Power Up Waveforms Power Up Sequence in DDR-II+ SramPower Up Sequence DLL ConstraintsDC Electrical Characteristics Electrical CharacteristicsMaximum Ratings Range AmbientCapacitance AC Electrical CharacteristicsThermal Resistance Parameter Description Test Conditions Max UnitAC Test Loads and Waveforms AC Test Loads and WaveformsCypress Consortium Description 375 MHz 333 MHz 300 MHz Unit Switching CharacteristicsParameter Min Max DLL TimingRead/Write/Deselect Sequence 29, 30, 31 Switching WaveformsNOP Read NOP WriteOrdering Information 300 Ball Fbga 15 x 17 x 1.4 mm Package DiagramDocument History ECN No Issue Orig. Description of Change DateREV
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