Importance

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Abstract

The present invention provides a data processing apparatus and method of testing a master logic unit within a data processing apparatus, the data processing apparatus comprising one or more master logic units for accessing a bus in order to initiate processing requests, and a test controller for testing logic units of the data processing apparatus. Further, an arbiter is provided for receiving bus request signals from the test controller and the one or more master logic units, and for applying predetermined priority criteria to control access to the bus by the test controller and the master logic units, the predetermined priority criteria identifying the relative priority of each master logic unit and the test controller. In a normal test mode, the test controller has a higher priority than any of the master logic units to be tested. However, in a master test mode, when master functionality of a first master logic unit is to be tested by the test controller, the arbiter is arranged to receive a priority access signal to cause the arbiter to assign the first master logic unit a higher priority than the test controller, in order to allow the first master logic unit to have access to the bus in order to generate a test processing request. By this approach, the master logic unit being tested can fully exercise its master functionality, since the master logic unit is allowed to drive processing requests onto the bus in a controlled manner.

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First Claim