Initialization/Application Information

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 VDD.

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 VDD or left unconnected.

31.6.2 Nonscan Chain Operation

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.

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MCF5282 User’s Manual

MOTOROLA

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Image 742
Motorola MCF5282, MCF5281 user manual Nonscan Chain Operation