Patent ID: 7568140

Claim:
An electronic circuit comprising: a plurality of configurable cells configured by a control circuit such as a test access controller when it receives a mode command signal: either in a functional state in which the configurable cells are functionally linked to logic cells with which they co-operate to form at least one logic circuit if the mode command signal is in a first state, or in a chained state in which the configurable cells are functionally connected in a chain to form a shift register, if the mode command signal is in a second state, a detection circuit laid out to produce an active state signal if it detects a chained state of the configurable cells while the controller receives the mode command signal in the first state, the detection circuit comprising: a state cell comprising a first data input to which there is applied a signal having a reference value, a second data input connected to the output of a preceding configurable cell, a third selection input connected to the controller and an output connected to a following configurable cell, the state cell being: functionally connected in a chain between the preceding configurable cell and the following configurable cell if the configurable cells are in the chained state, said state cell producing an output signal representing the content of the chain, or functionally cut off if the configurable cells are in the functional state, said state signal then producing an output signal that represents the reference value, a comparison circuit comprising a first data input connected to the output of the state cell and a second data input on which the mode command signal is applied, to compare the output signal with the reference value when it receives the mode command signal and produce the active state signal if the value of the output signal is different from the reference value.