PURPOSE: To provide a circuit capable of making access to a memory shared by a picture output processing circuit and an input picture processing circuit operated asynchronously by a simple circuit constitution.
CONSTITUTION: The asynchronously operated input picture processing circuit 11, the picture output processing circuit 12 and a shared memory 18 are provided. Also, a memory access signal switching circuit 110 is provided. The input picture processing circuit 11 and the picture output processing circuit 12 synchronize with the same clock SYSCLK for memory access and make access to the memory 18 and also the access right of the picture output processing circuit 12 is given priority over the access right of the input picture processing circuit 11. By setting the processing operation cycle of the input picture processing circuit 11 longer than the sum of the memory access maximum time of the picture output processing circuit 12 and the memory access maximum time of the input picture processing circuit 11, the both circuits make access to the memory 18 without overlapping.
AZUMAI HIDEO
IWATSUBO SATOSHI
