| 摘要 |
PURPOSE:To easily realize the decision of a right of using a bus including the time of bus contention for the request of using the bus with a simplified constitution, by providing signal lines onto which reserve signals expressing the request of using the bus and the permission of using the bus, are sent, between two devices, and performing specific control. CONSTITUTION:The signal lines L1 and L2 onto which the reserve signals RSV0 and RSV1 expressing the request of using the bus, and the permission of using the bus, are provided between the two devices #0 and #1. And the RSV0 is set when its own system device #0 requests the use of the bus, and acquires the right of using the bus when no RSV1 of another system device #1 is present, and holds the RSV0 after the completion of the use of the bus. Also, when the RSV1 comes in from another system device #1, the RSV0 is reset only at time of nonusing the bus by its own system device #0, and the permission of using the bus is given to the another system device #1. In such a way, it is possible to realize the decision of the right of using the bus including the time of contention of the request of using the bus, with the simplified constitution, and uniformize the processings of both devices by acquiring evenly the right of using the bus by both devices. |
