Motorola MCF5281 ユーザーズマニュアル

31-12

MOTOROLA

 

Using the EXTEST instruction requires a circuit-board test environment that avoids
device-destructive configurations in which MCU output drivers are enabled into actively
driven networks.

Low-power stop mode considerations:

• The TAP controller must be in the test-logic-reset state to either enter or remain in 

the low-power stop mode. Leaving the test-logic-reset state negates the ability to 
achieve low-power, but does not otherwise affect device functionality.

• The TCLK input is not blocked in low-power stop mode. To consume minimal 

power, the TCLK input should be externally connected to V

DD

.

• The TMS, TDI, and TRST pins include on-chip pull-up resistors. For minimal 

power consumption in low-power stop mode, these three pins should be either 
connected to V

DD

 or left unconnected.

Keeping the TAP controller in the test-logic-reset state ensures that the scan chain test logic
is transparent to the system logic. It is recommended that TMS, TDI, TCLK, and TRST be
pulled up. TRST could be connected to ground. However, since there is a pull-up on TRST,
some amount of current results. The internal power-on reset input initializes the TAP
controller to the test-logic-reset state on power-up without asserting TRST.