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1.3. Functional Description

The Test Interface Controller has two fundamental modes of operation:

  • default bus master.

  • system test.

The default bus master is selected during reset, when an AMBA system is in low power mode (if supported) or when no other masters are requesting the bus. When granted as the default master the TIC performs no test functions but keeps the AMBA bus in a state such that:

  • No data transfers occurs (BTRAN = A-TRAN).

  • The bus is available to be granted to another master when requested (BLOK = LOW).

Table 1.2 shows that for system test an external tester must assert the external pins TREQA and TREQB:

Basic TIC operation
InputsOutputs
TREQATREQBTACKTIC mode

0

0

0

Acting as default bus master

1

0

0

Entering test mode

1

1

1

Test mode entered, ADDRESS vector.

X

X

X

During test

0

0

1

Leaving test mode

Note

During test at least one of TREQA and TREQB must be HIGH. If both are LOW this indicates end of test.

When entering test mode the TIC requests the bus. Once it is granted as the current bus master test mode is entered and the TACK signal is pulled HIGH.

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