APPARATUS AND METHOD FOR DETECTING AN APPROACHING ERROR CONDITION

摘要

An apparatus and method are provided for detecting an approaching error condition within a data processing apparatus. The data processing apparatus includes a second sequential storage structure which is arranged to latch the output signal generated by combinatorial circuitry dependent on a second clock signal. The second sequential storage structure has a main storage element to latch a value of the output signal for provision to subsequent combinatorial circuitry, and transition detection circuitry for detecting a change of the value of the output signal latched by the main storage element during a predetermined timing window, said change indicating an approaching error condition whilst the value stored in the main storage element is still correct. The second sequential storage structure can be operated in either a first mode of operation or a second mode of operation. In the first mode of operation, the predetermined timing window is a timing window ahead of a time at which the main storage element latches said value of the output signal, to thereby enable an approaching setup timing error due to a propagation delay within the combinatorial circuitry to be detected. In the second mode of operation, the predetermined timing window is a timing window after the time at which the main storage element latches said value of the output signal such that an approaching hold timing error due to an increase in skew between the first and second clock signals is detected. Such a technique provides a simple and efficient mechanism for detecting a variety of approaching error conditions whilst the second sequence storage structure continues to operate correctly.