| 摘要 |
PROBLEM TO BE SOLVED: To precisely and securely sample reception data without dropping the communication speed by providing a reset means for resetting a frequency- dividing operation when reception data changes and starting the frequency- dividing operation after prescribed time passes for a main device. SOLUTION: The reset circuit 17 of a card reader/writer outputs a reset signal to a clock frequency-dividing circuit 11 with the rise/fall of reception data and resets the frequency-dividing operation. The reset circuit 17 holds a reset state only for prescribed time t0 after the frequency-dividing operation is set. The clock frequency-dividing circuit 11 is started after prescribed time t0 passes and the frequency-dividing operation is started. The frequency-dividing operation is reset again at timing when next data changes and it is resumed after a prescribed time t0 passes. Reception data of the card reader/writer is sampled by the rise of the reception clock of the card reader/writer, which is the frequency-divided output of the clock frequency-dividing circuit 11. |
