BENTLY 330103-00-03-05-02-05線纜軟件初始化開(kāi)關(guān)或跳線打開(kāi)時(shí)啟用的大多數(shù)功能其他模塊通過(guò)在上設(shè)置控制寄存器來(lái)啟用MVME177。在通電或重置時(shí)，包含177Bug調(diào)試包設(shè)置了許多這些寄存器。具體的編程細(xì)節(jié)可以通過(guò)研究M68060微處理器用戶手冊(cè)。您也可以查看詳細(xì)信息單板中給出的所有MVME177板載寄存器計(jì)算機(jī)程序員參考指南。
BENTLY 330103-00-03-05-02-05線纜多微處理器編程注意事項(xiàng)良好的編程實(shí)踐要求一次只能使用一個(gè)MPU控制MVME177控制寄存器。特別值得注意的是：? 修改地址映射的寄存器? 需要兩個(gè)周期才能訪問(wèn)的寄存器? VMEbus中斷請(qǐng)求寄存器本地重置操作本地重置（LRST）是系統(tǒng)重置（SRST）的子集。本地重置can可通過(guò)五種方式生成：? 看門(mén)狗計(jì)時(shí)器過(guò)期? 按下前面板重置開(kāi)關(guān)（如果系統(tǒng)控制器功能已禁用）? 在GCSR中的板控制寄存器中斷言位? 系統(tǒng)重置*? 通電復(fù)位注：GCSR允許VMEbus主機(jī)重置本地公共汽車(chē)此功能非常危險(xiǎn)，應(yīng)使用小心。局部重置功能是一個(gè)局部系統(tǒng)重置，而不是完整的系統(tǒng)重置，如通電重置或系統(tǒng)重置*。當(dāng)本地總線重置信號(hào)為斷言，本地總線循環(huán)可能會(huì)中止。這個(gè)VMEchip2連接到本地總線和VMEbus和中止的循環(huán)是否為VMEbus，可能會(huì)導(dǎo)致不穩(wěn)定的操作。本地處理器和VMEbus主機(jī)應(yīng)使用中斷或郵箱位置；正常情況下不應(yīng)使用重置通信。只有當(dāng)本地處理器停止或本地總線掛起重置是最后的手段。當(dāng)MVME177處于重置狀態(tài)時(shí)，對(duì)其的任何VMEbus訪問(wèn)都是忽略。如果啟用了全局總線計(jì)時(shí)器，則會(huì)生成總線錯(cuò)誤。
Software Initialization
Most functions that have been enabled with switches or jumpers on
other modules are enabled by setting control registers on the
MVME177. At power up or reset, the EPROMs that contain the
177Bug debugging package set up the default values of many of
these registers.
Specific programming details may be determined by study of the
M68060 Microprocessor User's Manual. You can also check the details
of all the MVME177 onboard registers as given in the Single Board
Computers Programmer's Reference Guide.
Multi-MPU Programming Considerations
Good programming practice dictates that only one MPU at a time
has control of the MVME177 control registers.
Of particular note are:
? Registers that modify the address map
? Registers that require two cycles to access
? VMEbus interrupt request registers
Local Reset Operation
Local reset (LRST) is a subset of system reset (SRST). Local reset can
be generated five ways:
? Expiration of the watchdog timer? Pressing the front panel RESET switch (if the system
controller function is disabled)
? Asserting a bit in the board control register in the GCSR
? SYSRESET*
? Power-up reset
Note The GCSR allows a VMEbus master to reset the local
bus. This feature is very dangerous and should be used
with caution. The local reset feature is a partial system
reset, not a complete system reset such as power-up
reset or SYSRESET*. When the local bus reset signal is
asserted, a local bus cycle may be aborted. The
VMEchip2 is connected to both the local bus and the
VMEbus and if the aborted cycle is bound for the
VMEbus, erratic operation may result.
Communications between the local processor and a
VMEbus master should use interrupts or mailbox
locations; reset should not be used in normal
communications. Reset should be used only when the
local processor is halted or the local bus is hung and
reset is the last resort.
Any VMEbus access to the MVME177 while it is in the reset state is
ignored. If a global bus timer is enabled, a bus error is generated.
