| 摘要 |
PROBLEM TO BE SOLVED: To disconnect a CPU bus from a local bus during DMA transfer and to allow a CPU to access a device on the local bus. SOLUTION: A bus switch 930 is connected between the CPU bus and the local bus. A DMA controller part 910 disconnects the CPU bus from the local bus by the bus switch 930 and performs DMA transfer from an SRAM 982b to a device in an image processing part 20 on the local bus in a burst mode. When an interruption request (NCS_IPS=1) is outputted from the CPU 990 to the image processing part 20, the DMA transfer is stopped and the CPU bus is connected to the local bus by the bus switch 930 to provide the control right of the local bus to the CPU 990. After the stop of the interruption request, the DMA controller part 910 disconnects the CPU bus from the local bus by the bus switch 930 and automatically restarts the DMA transfer from the interrupted position. COPYRIGHT: (C)2005,JPO&NCIPI
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