| 摘要 |
PURPOSE:To improve the reliability and also to facilitate an easy extension, etc. for a common bus connection circuit by controlling the signal transmitting direction of a bi-directional bus driving circuit by means of the signal on a common bus and therefore attaining a connection between optional common buses as well as simplifying the system constitution. CONSTITUTION:When a function block connected to a common bus 100 transmits data to a bus 100, the function block drives the bus 100 to an earth potential. Thus a set/reset FF510 is set via a 4-input NOA gate 250, and ''1'' is delivered. Then the driving direction of a bi-directional bus driving circuit 200 is inverted. As a result, the data signal transmitted from the function block connected to the bus 100 is supplied to the 1st input terminal of other bi-directional bus driving circuits 201-203 respectively through the circuit 200. Thus the data signal from the function block is delivered to all common buses 101-103, and the data can be received by an optional function block. That is, the system constitution is simplified and an extension, etc. can be facilitated with improvement of reliability for a common bus connecting circuit. |
