| 摘要 |
PURPOSE:To allow the title equipment to correspond to a change when maximum frame length is converted into a receivable state by changing a parameter setting method in a direct memory access controller (DMAC) in accordance with validity/invalidity in the reception of frame data with the maximum length. CONSTITUTION:When frame data are received by a communication control circuit 4, the received data are transferred to a frame memory in a RAM 3 by the DMAC 5. When valid end of reception is detected by a frame validity deciding circuit 11, the leading address and data length of a frame memory to be successively received are read out from a stand-by register group 6 and set up in the DMAC 5. Consequently, an interruption control circuit 13 is started and a receiving interruption is generated in an MPU 1. When a buffer for storing the frame data with the maximum length can not be secured, the leading address of the stand-by buffer in the RAM 3 and maximum allowable length are stored in the RAM 3. |
