| 摘要 |
<p>PURPOSE:To count pulses of relatively high frequency through a small amount of hardware with high resolution by utilizing a central processor. CONSTITUTION:A counter 11 counts clock pulses 11. A register 12 holds a count value sent from a CPU15 through a data bus 16. A comparing circuit 13 compares the value of the counter 11 with the value of the register 12 and outputs a signal when they coincide with each other. A permission flag circit 17 uses the coincidence signal sent from the comparing circuit 13 to decide on whether a coincidence flag circuit 14 is set or not. A reading circuit 19 reads the most significant digit bit of the counter 11 and outputs it to the CPU15 through the data bus 16. The CPU15 is capable of accessing the register 12 and reading circuit 19 and sets and resets the permission flag circuit 17 through the data bus 16.</p> |
