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Q.13.1
How can the JTAG function be reset when JTAG is not used?
A.13.1
JTAG can be reset by two methods: one in which the JRST_B pin is used and one in which the JRST_B pin is not
used.
When the JRST_B pin is not used:
The JTAG function can be reset by using the JMS and JCK pins while the JRST_B pin is pulled up.
Input the clock five times to the JCK pin while the JMS pin is pulled up.
When the JRST_B pin is used:
The JTAG function can be reset by inputting a low level to the JRST_B pin while the JRST_B and JMS pins are
pulled up. At this time, the low-level width must be one clock cycle of the SCLK input or more. If the JRST_B
pin is kept low (pulled down, etc.), the JTAG function is reset, regardless of the status of the JMS pin.
Reference: µ PD98409 User's Manual 8.6 Initializing TAP Controller
CHAPTER 13 JTAG
Information S14769EJ1V0IF00
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