Asynchronous communication

An asynchronous bridge arranged to transfer data from a first bus to a second bus across an asynchronous interface between said first and second buses, said asynchronous bridge comprising:

• a bus slave module, connected to the first bus, comprising a forward-channel initiator in a first power and/or clock domain;
• and
• a bus master module, connected to the second bus, comprising a forward-channel terminator in a second power and/or clock domain;
• wherein the forward-channel initiator and the forward-channel terminator are in communication to form a forward lockable mutex for arbitrating access to signals used to transfer data from the first power and/or clock domain to the second power and/or clock domain;
• wherein the asynchronous bridge is arranged such that:
• if said lockable mutex is locked, the asynchronous bridge uses a forward data channel to transfer data between said first and second power and/or clock domains;
• if said lockable mutex is unlocked, said forward channel initiator toggles a status request signal and the forward channel terminator toggles a status acknowledge signal in response;
• the lockable mutex thereby becoming locked.