Abstract: Data is written from a first domain to a FIFO memory buffer in a second domain. The first domain uses a first clock signal, the second domain uses a second clock signal and the memory buffer uses the first clock signal that is delivered alongside the data. The data is read from the memory buffer using the second clock signal. A read pointer is adjusted and synchronised with the delivered first clock signal. A token is generated using the delivered first clock signal, based on the read pointer. The token represents a capacity of the memory buffer having been made available. The token is passed to the first domain and synchronised with the first clock signal. The writing of data to the memory buffer is controlled based on a comparison between the synchronised token and a previously received token.

Abstract: Signal synchronizers synchronize input signals with a clock signal. The input of each synchronizer is connected to a first input and the output of each synchronizer is connected to a second input of a respective first gate arrangement. The first gate arrangements provide an output signal only if there is an input signal on the first input and none on the second input or vice versa. The outputs of each of the first gate arrangements is connected to respective inputs of a second gate arrangement, which provides an output signal if there is a signal on any of its inputs. The output of the second gate arrangement is connected to a third gate arrangement which operates such that the clock signal to the synchronizers is only enabled when there is a change to the state of a signal received at the input of at least one of the synchronizers.

Abstract: Data is written from a first domain to a FIFO memory buffer in a second domain. The first domain uses a first clock signal, the second domain uses a second clock signal and the memory buffer uses the first clock signal that is delivered alongside the data. The data is read from the memory buffer using the second clock signal. A read pointer is adjusted and synchronised with the delivered first clock signal. A token is generated using the delivered first clock signal, based on the read pointer. The token represents a capacity of the memory buffer having been made available. The token is passed to the first domain and synchronised with the first clock signal. The writing of data to the memory buffer is controlled based on a comparison between the synchronised token and a previously received token.

Abstract: Signal synchronisers synchronise input signals with a clock signal. The input of each synchroniser is connected to a first input and the output of each synchroniser is connected to a second input of a respective first gate arrangement. The first gate arrangements provide an output signal only if there is an input signal on the first input and none on the second input or vice versa. The outputs of each of the first gate arrangements is connected to respective inputs of a second gate arrangement, which provides an output signal if there is a signal on any of its inputs. The output of the second gate arrangement is connected to a third gate arrangement which operates such that the clock signal to the synchronisers is only enabled when there is a change to the state of a signal received at the input of at least one of the synchronisers.