Cypress CY7C1470BV33 Computer Hardware User Manual


 
CY7C1470BV33
CY7C1472BV33, CY7C1474BV33
Document #: 001-15031 Rev. *C Page 14 of 30
possible to capture all other signals and simply ignore the value
of the CLK 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 balls.
Note that since the PRELOAD part of the command is not imple-
mented, putting the TAP to the Update-DR state while performing
a SAMPLE/PRELOAD instruction has the same effect as the
Pause-DR command.
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 balls. The advantage of the
BYPASS instruction is that it shortens the boundary scan path
when multiple devices are connected together on a board.
Reserved
These instructions are not implemented but are reserved for
future use. Do not use these instructions.
Figure 4. TAP Timing
t
TL
Test Clock
(TCK)
123456
T
est Mode Select
(TMS)
t
TH
Test Data-Out
(TDO)
t
CYC
Test Data-In
(TDI)
t
TMSH
t
TMSS
t
TDIH
t
TDIS
t
TDOX
t
TDOV
DON’T CARE UNDEFINED
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