A circuit for asynchronous data transfer includes a slave device having an asynchronous slave clock for transferring data to a master device having a master clock. The slave clock is a non-continuous clock signal. The slave device includes a clock detection circuit, a register bank, a temporary storage register, and a datapath selector. The slave device receives a data transfer command from the master device. The clock detection circuit detects a presence of the slave clock signal and generates a sync signal. To transfer the data to the master device, the datapath selector selects one of the temporary storage register and the register bank based on the sync signal. The slave device ensures seamless data transfer to the master device regardless of the presence or absence of the slave clock signal.