| 摘要 |
PURPOSE:To reduce the load on a CPU due to the intervention of software interrupt processing and the load on a timer used for monitoring by bringing timer functions for monitoring serial transmission and reception under the control of one timer together. CONSTITUTION:The timer O16 which is started in response to automatic data transfer processing by a transmission I/O request outputs a timer-0 counting end signal 69 to a request control part 31 for I/O at specific intervals of time based upon a value set in a timer 0-modulo register 18. The I/O request control part 31 reports timer-0 automatic data transfer processing to an I/O request accepting part 32 and decreases the contents of a timer counter part (WDC)47 for monitoring an I/O request generating origin by one. When normal serial transmission is performed, reception completion is reported to a serial data transfer device 1 within a specific time to stop the subtraction of WDC47. On the other hand, if abnormality occurs in the serial transmission, the subtraction of EDC47 is not stopped and the value becomes 0, detecting 0. |
