Cypress CY7C0852AV, CY7C0853AV manual Ieee 1149.1 Serial Boundary Scan Jtag, Performing a TAP Reset

CY7C0850AV, CY7C0851AV CY7C0852AV, CY7C0853AV

IEEE 1149.1 Serial Boundary Scan (JTAG) [13]

The CY7C0850AV/CY7C0851AV/CY7C0852AV/CY7C0853AV incorporates an IEEE 1149.1 serial boundary scan test access port (TAP). The TAP controller functions in a manner that does not conflict with the operation of other devices using 1149.1-compliant TAPs. The TAP operates using JEDEC-standard 3.3V I/O logic levels. It is composed of three input connections and one output connection required by the test logic defined by the standard.

Table 4. Identification Register Definitions

Performing a TAP Reset

A reset is performed by forcing TMS HIGH (VDD) for five rising edges of TCK. This reset does not affect the operation of the devices, and may be performed while the devices are operating. An MRST must be performed on the devices after power up.

Performing a Pause/Restart

When a SHIFT-DR PAUSE-DR SHIFT-DR is performed the scan chain outputs the next bit in the chain twice. For example, if the value expected from the chain is 1010101, the device outputs a 11010101. This extra bit causes some testers to report an erroneous failure for the devices in a scan test. Therefore the tester should be configured to never enter the PAUSE-DR state.

Instruction Field	Value	Description
Revision Number (31:28)	0h	Reserved for version number.
Cypress Device ID (27:12)	C001h	Defines Cypress part number for the CY7C0851AV
	C002h	Defines Cypress part number for the CY7C0852AV and CY7C0853AV
	C092h	Defines Cypress part number for the CY7C0850AV
Cypress JEDEC ID (11:1)	034h	Allows unique identification of the DP family device vendor.
ID Register Presence (0)	1	Indicates the presence of an ID register.

Table 5. Scan Registers Sizes

	Register Name		Bit Size
	Instruction		4
	Bypass		1
	Identification		32
	Boundary Scan		n[14]
Table 6. Instruction Identification Codes
Instruction	Code		Description
EXTEST	0000	Captures the Input/Output ring contents. Places the BSR between the TDI and TDO.
BYPASS	1111	Places the BYR between TDI and TDO.
IDCODE	1011	Loads the IDR with the vendor ID code and places the register between TDI and TDO.
HIGHZ	0111	Places BYR between TDI and TDO. Forces all CY7C0851AV/CY7C0852AV/
		CY7C0853AV output drivers to a High-Z state.
CLAMP	0100	Controls boundary to 1/0. Places BYR between TDI and TDO.
SAMPLE/PRELOAD	1000	Captures the input/output ring contents. Places BSR between TDI and TDO.
NBSRST	1100	Resets the non-boundary scan logic. Places BYR between TDI and TDO.
RESERVED	All other codes	Other combinations are reserved. Do not use other than the above.

Notes

12.The “X” in this diagram represents the counter upper bits.

13.Boundary scan is IEEE 1149.1-compatible. See “Performing a Pause/Restart” for deviation from strict 1149.1 compliance.

14.See details in the device BSDL files.

Document #: 38-06070 Rev. *H Page 12 of 32

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