UFC911B106 3BHE037864R0106控制处理器,ABB中文说明

VMEbus系统控制器VMEchip提供的众多功能之一是VMEbus系统控制器功能。系统控制器包括以下内容：❏ VMEbus全局超时计时器❏ 系统时钟（SYSCLK*）驱动程序❏ 仲裁人❏ 中断确认（IACK*）菊花链驱动程序。此处还描述了系统重置实用程序，因为它已启用当MVME147为系统控制器时。系统控制器功能由标题J3启用/禁用。

UFC911B106 3BHE037864R0106控制处理器当MVME147系统控制器，系统控制器（SCON）LED亮起。VMEbus超时当数据选通（DS0*或DS1*）处于活动状态，当两者都处于非活动状态时，将被禁用。如果在数据选通停止前计时器超时，总线错误（BERR*）信号被激活。超时时间由计时器间隔寄存器，可以是102µs、205µs、410µs或无限。系统时钟实用程序

16 MHz系统时钟被驱动到VMEbus SYSCLK上*VMEchip系统时钟驱动器的信号线。

VMEchip实现了两种不同的仲裁模式。他们优先顺序和循环。该模式可由软件选择。在优先模式下，仲裁器优先处理总线请求向最高优先级的请求者发出信号并做出响应。仲裁器还通过激活当来自更高优先级的请求时，总线清除（BCLR*）信号主节点已在循环模式下接收，仲裁人在循环模式下分配总线优先权基础。循环赛中不使用BCLR*信号模式仲裁器还包含超时功能。它激活总线繁忙（BBSY*），如果请求者未在超时期。超时时间段可由软件选择，并且可以设置为410µs或无穷大。IACK*菊花链驱动器IACK*菊花链驱动器激活中断确认

每当中断处理程序确认中断请求。

VMEbus System Controller

One of the many functions provided by the VMEchip is the

VMEbus system controller function. The system controller includes

the following:

❏ VMEbus global time-out timer

❏ System Clock (SYSCLK*) driver

❏ Arbiter

❏ Interrupt Acknowledge (IACK*) daisy-chain driver.

The system reset utility is also described here because it is enabled

when the MVME147 is system controller. The system controller

function is enabled/disabled by header J3. When the MVME147 is

system controller, the System Controller (SCON) LED is turned on.

VMEbus Time-Out

The VMEbus timer is started when either Data Strobe (DS0* or

DS1*) goes active and is disabled when they both go inactive. If the

timer times out before the data strobes go inactive, the Bus Error

(BERR*) signal is activated. The time-out period is controlled by the

timer interval register and may be 102 µs, 205 µs, 410 µs, or infinite.

System Clock Utility

The 16 MHz system clock is driven onto the VMEbus SYSCLK*

signal line by the VMEchip system clock driver.

Arbiter

The VMEchip implements two different arbitration modes. They

are prioritized and round-robin. The mode is software selectable.

In the prioritized mode, the arbiter prioritizes the bus request

signals and responds with grant to the highest priority requester.

The arbiter also informs the current bus master by activating the

Bus Clear (BCLR*) signal when a request from a higher priority

master has been receivedIn the round-robin mode, the arbiter assigns the bus on a rotating

priority basis. The BCLR* signal is not used in the round-robin

mode.

The arbiter also contains a time-out feature. It activates Bus Busy

(BBSY*) on its own if BBSY* is not activated by the requester within

the time-out period. The time-out period is software selectable and

may be set to 410 µs or infinite.

IACK* Daisy-Chain Driver

The IACK* daisy-chain driver activates the interrupt acknowledge

daisy-chain whenever an interrupt handler acknowledges an

interrupt request.