Signal selecting device controlled by a serially transmitted mode signal requiring but one terminal
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorToshihiko Hori
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Abstract
In a signal selecting device, a mode determination portion 61 comprises a shift register 11, a clock generating portion 20 and decoder 51. The clock generating portion 20 receives a mode signal M and generates a clock signal CK1 used for decoding the mode signal M from a system clock SYS. The shift register 11 receives the mode signal M and the clock signal CK1 and outputs signals Q.sub.0 to Q.sub.3. The decoder 51 receives the output from the shift register 11 and outputs control signals S.sub.00 to S.sub.03. Therefore, there needs only one terminal for receiving the mode signal M and no terminal for receiving a clock.
Claims16
A signal selecting device, comprising:
- (a) a mode determination portion having:
- (a-1) an input terminal for receiving a mode signal;
- and
- (a-2) decoder means for decoding said mode signal in accordance with a clock signal into a pluraity of control signals to be outputted, said mode determination portion including a clock signal generator providing said clock signal in response to a system clock and said mode signal,
- said mode determination portion outputting a plurality of operation mode signals in accordance with said plurality of control signals;
- and
- (b) a logical processing portion having:
- (b-1) a plurality of first input ends for receiving a plurality of signals to be selected respectively;
- (b-2) a plurality of second input ends for receiving said plurality of operation mode selection signals;
- and
- (b-3) an output end for outputting one of said signals to be selected in accordance with said plurality of operation mode selection signals.
Dependencies are inferred from the claim text.