Abstract: A handshake circuit portion for performing a handshake procedure to facilitate data reception by an associated circuit portion is provided. The handshake circuit portion comprises a request signal input for detecting a request signal from a further handshake circuit portion associated with a further circuit portion, an acknowledge signal output for asserting an acknowledge signal for the further handshake circuit portion, and a blocking signal input for detecting a blocking signal from the associated circuit portion. The handshake circuit portion is arranged to detect a request signal via the request signal input, determine if a blocking signal is present on the blocking signal input, and if a blocking signal is not present on the blocking signal input, respond to the request signal by asserting an acknowledge signal via the acknowledge signal output.

Abstract: An integrated-circuit device comprises a source register in a reset domain, a destination circuit outside the reset domain, and a reset checking circuit. The checking circuit comprises a buffer outside the reset domain for receiving data values output by the source register, a reset detector, and reset checking logic. The checking logic detects a new data value output by the source register, checks whether a reset of the reset domain has been detected, and contingently outputs a control signal for controlling whether the destination circuit receives the new data value from the buffer. The reset detector signals whether a reset has been detected by using a feedback path to hold a predetermined value in a resettable latch until the latch receives a reset signal, and to hold a different value in the latch after receiving a reset signal.

Abstract: An integrated-circuit device comprises a source register in a reset domain, a destination circuit outside the reset domain, and a reset checking circuit. The checking circuit comprises a buffer outside the reset domain for receiving data values output by the source register, a reset detector, and reset checking logic. The checking logic detects a new data value output by the source register, checks whether a reset of the reset domain has been detected, and contingently outputs a control signal for controlling whether the destination circuit receives the new data value from the buffer. The reset detector signals whether a reset has been detected by using a feedback path to hold a predetermined value in a resettable latch until the latch receives a reset signal, and to hold a different value in the latch after receiving a reset signal.

Abstract: A system (1) for transferring a data signal (sig_fast) from a first clock domain (4) to a second clock domain (8). The first clock domain (4) has a first clock (ck_fast) with a frequency greater than the frequency of a second clock (ck_slow) in the second clock domain (8). The system (1) also has a signal input (10) for receiving an input signal (sig_fast) from the first clock domain (4), means (16, 18) for checking whether the second clock (ck_slow) is in a part of its cycle away from a forthcoming transition, and means (22) for transferring the input signal (sig_fast) to the second clock domain (8) if the checking means (16, 18) determines that the second clock (ck_slow) is in part of its cycle away from a forthcoming transition. The checking means (16, 18) are clocked by the first clock (ck_fast).

Abstract: An arrangement for transferring a data signal (data_a) from a first clock domain (2) to a second clock domain (4) in a digital system. The arrangement has a signal input (6, 7) for receiving an input signal (data_a) from the first clock domain (2), means (6, 7) for storing the input signal (data_a), and means (12, 13) for transferring the input signal (data_a) to the second clock domain (4) following a transition in the clock signal (ck) of the second clock domain (4).

Abstract: A digital circuit portion comprises a flip-flop (20) having a clock input (22) and an output (data); a clock signal (ck); and a gate (24) between said clock signal (ck) and said clock input (22), said gate (24) being arranged selectively to couple the clock signal (ck) to the clock input (22) in dependence upon the output of the flip-flop (20).

Abstract: An arrangement for transferring a data signal (data_a) from a first clock domain (2) to a second clock domain (4) in a digital system. The arrangement has a signal input (6, 7) for receiving an input signal (data_a) from the first clock domain (2), means (6, 7) for storing the input signal (data_a), and means (12, 13) for transferring the input signal (data_a) to the second clock domain (4) following a transition in the clock signal (ck) of the second clock domain (4).

Abstract: A system (1) for transferring a data signal (sig_fast) from a first clock domain (4) to a second clock domain (8). The first clock domain (4) has a first clock (ck_fast) with a frequency greater than the frequency of a second clock (ck_slow) in the second clock domain (8). The system (1) also has a signal input (10) for receiving an input signal (sig_fast) from the first clock domain (4), means (16, 18) for checking whether the second clock (ck_slow) is in a part of its cycle away from a forthcoming transition, and means (22) for transferring the input signal (sig_fast) to the second clock domain (8) if the checking means (16, 18) determines that the second clock (ck_slow) is in part of its cycle away from a forthcoming transition. The checking means (16, 18) are clocked by the first clock (ck_fast).

Abstract: A digital circuit portion comprises a flip-flop (20) having a clock input (22) and an output (data); a clock signal (ck); and a gate (24) between said clock signal (ck) and said clock input (22), said gate (24) being arranged selectively to couple the clock signal (ck) to the clock input (22) in dependence upon the output of the flip-flop (20).