| 摘要 |
<p>PROBLEM TO BE SOLVED: To set an insertion order of a function block as optional, to reduce the number of signal lines of a bus and to make a device compact. SOLUTION: In the case that a function block 40 is inserted into a bus at a state that a function block 50 is mounted, when power supply voltage of the function block 40 is determined, a bus clock CK is started to be supplied from a clock supplying circuit 41. A fact that clock interruption lasts until the clock CK is normally supplied by the circuit 41 is detected and a clock interruption reset signal S51 is turned on by a clock interruption detecting circuit 51. The signal S51 is turned off after a fixed period from the clock CK is judged to be normally inputted by the circuit 51. Consequently, an interface circuit 54 is normally reset by a fact that an internal reset signal is turned on while the clock CK is supplied and communication with a serial bus 30 is normally performed when the signal S52 is turned off.</p> |
