RELIANCE 57C430B处理器模块
这些特性使该装置非常适合嵌入式应用，尤其是不能使用标准硬盘驱动器和软盘驱动器的应用。概述VMIVME-7740提供了一个用户可编程的82C54内部计时器/计数器。82C54提供三个独立的16位定时器，每个定时器的工作频率为1或2MHz，由跳线E8的配置决定；参考第32页表2-2。这些计时器对用户完全可用，不专用于任何PC/AT功能。这些计时器可用于生成系统中断。事件可以通过轮询计时器或通过82C54外部电路生成系统中断来计时。外部电路由产生中断的逻辑和指示三个定时器中哪一个产生中断的定时器中断状态寄存器组成。82C54定时器映射在I/O地址$500。计时器使用的中断是IRQ5。定时器中断状态寄存器可通过电源管理I/O地址空间使用。对该空间的访问在下面的“定时器中断状态”部分中进行了说明。
These features make the unit ideal for embedded applications, particularly applications where standard hard drives and floppy disk drives cannot be used.General The VMIVME-7740 provides a user-programmable 82C54 internal timer/counter. The 82C54 provides three independent, 16-bit timers, each operating at 1 or 2 MHz clock speed determined by the configuration of jumper E8; reference Table 2-2 on page 32. These timers are completely available to the user and are not dedicated to any PC/AT function. These timers may be used to generate system interrupts. Events can be timed by either polling the timers or generating a system interrupt via circuity external to the 82C54. The external circuity consists of logic which generates the interrupt and a Timer Interrupt Status register which indicates which of the three Timers generated an interrupt.The 82C54 timers are mapped at I/O address $500. The interrupt used by the Timers is IRQ5. The Timer Interrupt Status register is available via the Power Management I/O address space. The access to this space is explained in the “Timer Interrupt Status” section below.
