EMERSON 1C31129G04控制DCS系統
系統時(shí)鐘系統時(shí)鐘由振蕩器驅動(dòng)。下表定義了各種配置的時(shí)鐘頻率。實(shí)時(shí)時(shí)鐘輸入RTC時(shí)鐘輸入由控制和定時(shí)器PLD生成的1MHz時(shí)鐘驅動(dòng)。這為MC864xD PIC定時(shí)器提供了一個(gè)固定的時(shí)鐘基準，軟件可以將其用作已知的定時(shí)基準。4.13.3本地總線(xiàn)控制器時(shí)鐘分頻器本地總線(xiàn)控制器（LBC）時(shí)鐘輸出連接到PLD，但不由內部邏輯使用4.14復位控制邏輯MVME7100上有多個(gè)復位源。以下源生成板級重置：? 通電? 復位開(kāi)關(guān)? 看門(mén)狗計時(shí)器? 系統控制寄存器（BRD_RST）? VME總線(xiàn)重置板級硬重置為整個(gè)SBC生成重置，包括處理器、本地PCI/PCI-X總線(xiàn)、以太網(wǎng)PHY、串行端口、閃存設備和PLD。如果MVME7100被配置為VME系統控制器，VMEbus和本地Tsi148重置輸入也被重置。4.15實(shí)時(shí)時(shí)鐘電池有一個(gè)車(chē)載電池支架，可方便地更換+3.0V紐扣電池鋰電池（BR2325），為車(chē)載實(shí)時(shí)時(shí)鐘提供備用電源。蓄電池開(kāi)關(guān)電路提供+3.3V和蓄電池電壓之間的自動(dòng)切換。
System Clock The system clock is driven by an oscillator. The following table defines the clock frequencies for various configurations.Real Time Clock Input The RTC clock input is driven by a 1MHz clock generated by the Control and Timers PLD. This provides a fixed clock reference for the MC864xD PIC timers which software can use as a known timing reference. 4.13.3 Local Bus Controller Clock Divisor The Local Bus Controller (LBC) clock output is connected to the PLD but is not used by the internal logic 4.14 Reset Control Logic There are multiple sources of reset on the MVME7100. The following sources generate a board level reset: ? Power-up ? Reset switch ? Watchdog timer ? System control register (BRD_RST) ? VMEbus reset A board level hard reset generates a reset for the entire SBC including the processor, local PCI/PCI-X buses, Ethernet PHYs, serial ports, flash devices, and PLD(s). If the MVME7100 is configured as the VME system controller, the VMEbus and local Tsi148 reset input are also reset. 4.15 Real Time Clock Battery There is an on-board battery holder that provides easy replacement of a +3.0V button cell lithium battery (BR2325) which provides back-up power to the on-board Real Time Clock. A battery switching circuit provides automatic switching between the +3.3V and battery voltages.
