单片机应用于过程控制,巡回检测以及智能仪器仪表中,常需要实时时钟。本文以MCS—48系列8039单片机为例介绍三种实时时钟的设计方法。 (一) 利用单片机内定时器/计数器 8039片内具有一个8位定时器/计数器。当执行启动定时器指令STRT,T后,内部时钟经32分频加到定时器的输入端。在频率为6兆赫的晶振控制下,每80μS给一个计 Microcontroller used in process control, circuit detection and intelligent instrumentation, often require real-time clock. In this paper, MCS-48 Series 8039 MCU as an example to introduce three kinds of real-time clock design. (A) the use of single-chip timer / counter 8039 has an 8-bit timer / counter. When the start of the timer instruction STRT, T, the internal clock divided by 32 to the timer input. Under the control of a crystal with a frequency of 6 MHz, a meter is given every 80 μS