
19
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32170/32174 Group User's Manual (Rev. 2.1)
JTAG
19.4 Basic Operation of JTAG
19.4.4 Examining and Setting Data Registers
To inspect or set the data register, follow the procedure described below.
(1) To access the test access port (JTAG) for the first time, enter test reset (to initialize the test
circuit). Test reset can be entered by one of the following two methods:
Pull JTRST pin input low
Drive JTMS pin input high and enter JTCK for 5 cycles or more
(2) Set JTMS = low to go to "Run-Test/Idle" state. To continue the idle state, hold JTMS input
low.
(3) Set JTMS = high to exit "Run-Test/Idle" state and perform IR path sequence. In IR path
sequence, specify the data register you want to inspect or set.
(4) Subsequently, perform DR path sequence. For the data register specified in IR path
sequence, enter setup data from the JTDI pin and read out reference data from the JTDO
pin.
(5) If after DR path sequence is completed you want to proceed and perform IR path sequence
or DR path sequence, enter JTMS = high to return to "Select-DR-Scan" state. If after a series
of IR and DR path sequence processing is completed you want to wait for the next
processing, enter JTMS = low to go to "Run-Test/Idle" state and retain the state.