Patent ID: 8717078

Claim:
A latching device configured to receive, hold and output a data value in response to a clock signal, said clock signal periodically switching between a first and a second value, said latching device comprising: an input latching element configured to receive an input data value; and an output latching element configured to output said data value; wherein said input latching element is configured to receive a first clock signal and said output latching element is configured to receive a second clock signal, said first and second clock signals having a same frequency and phase but being inverted with respect to each other; wherein said input and output latching elements are each configured to be transparent and transmit data between an input and an output in response to said first value of a received clock signal and being opaque and holding said data value in response to a second value of said received clock signal, such that in response to said first and second clock signals said input data value is clocked through said input and output latching elements to said output; said latching device further comprising: a selecting device for selecting an operational data value or a diagnostic data value for input to said input latching element in response to a value of a diagnostic enable signal indicating a functional mode or a diagnostic mode; and a further latching element configured to be clocked by said second clock signal and being configured to be transparent and transmit data between an input and an output in response to said second clock signal having said first value and being opaque and holding said data value in response to said second clock signal having said second value, wherein said further latching element is configured to receive said second clock signal in response to said diagnostic enable signal indicating said diagnostic mode.