HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 734

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

26.6
1. An H-UDI command, once set, will not be modified as long as another command is not re-
2. Because chip operations are suspended in standby mode, H-UDI commands are not accepted.
3. The H-UDI is used for emulator connection. Therefore, H-UDI functions cannot be used when
4. Usage of the TRST pin as a boundary scan function is optional. In this LSI, the TAP controller
Figure 26.4 shows an example of circuit connection.
Rev. 1.00, 02/04, page 696 of 804
issued from the H-UDI. If the same command is given continuously, the command must be set
after a command (BYPASS, etc.) that does not affect chip operations is once set.
To maintain the TAP controller state before and after standby mode, TCK must be kept high
during the transition to standby mode.
using an emulator.
must be initialized simultaneously by the TRST pin at a power-on reset. Note however that in
other LSIs, a power-on reset function may be available instead of the TRST pin or
initialization of the TAP controller at a power-on reset may not be required. Take the following
points in consideration when applying a power-on reset signal to the TRST pin.
 A reset signal must always be applied when the power is turned on.
 The power-on reset circuit must be separated from the LSI so that the TRST signal of the
 Due to the opposite reason as described above, the power-on reset circuit must be separated
Figure 26.4 Example of Connecting Reset Signals without Mutual Interference
board tester does not affect the LSI operation. Resetting the TAP controller during board
testing may generate a TRST signal asynchronously. If the power-on reset circuit is not
separated in this case, the generated TRST signal will likely affect LSI operation during
board testing (e.g. system reset occurs asynchronously).
from the LSI so that the LSI's system reset does not affect the TRST signal of the board
tester. During board testing, the board tester controls the system reset signal via the
boundary scans to examine the connection of the LSI system reset signal. If the power-on
reset circuit is not separated in this case, the above operation resets the TAP controller, and
testing may not be performed correctly.
Usage Notes
System_Reset
TRST
Power-on
reset circuit
RESETP
TRST
LSI
ASEMD0
Vcc