| 摘要 |
PURPOSE:To transfer data using a DMA controller by providing a control circuit controlling the stop/start of a CRC arithmetic circuit by an output of a comparator during the operation of the CRC arithmetic circuit. CONSTITUTION:The CRC arithmetic circuit 1 inputting a serial data is provided with comparators 4, 5 comparing values of registers 2, 3 storing a serial data before the input to the CRC arithmetic circuit 1 with a value of a register storing a predetermined character and the control circuit controlling the stop/ start of the CRC arithmetic circuit 1 by the output of the said comparators during the CRC arithmetic. A received character is compared with a DLE character pattern and whether or not it is included in the CRC arithmetic is discriminated, the DLE of the 1st character is not included in the CRC arithmetic and the DLE of the 2nd DLE is included in the CRC arithmetic in the two consecutive DLE characters by the control and the control of a host CPU is not executed at a test part between control characters representing the head and end of the text. Thus, the data using the DMA controller is transferred.
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