BENTLY 330180-90-05通道温度模块
装运的EPROM通常用于车载调试器固件（177Bug），但可用于下载用户代码闪烁。EPROM只占1MB内存，但可以使用前2MB闪存共享前2MB空间。这个在混合模式下，EPROM仅占用ROM空间中的1MB空间并将在第二个1MB空间中重复（为未来扩展）。EPROM可以与2MB的Flash，或者可以用来编程所有4MB的Flash，然后是J8可以移除跳线，以仅使用闪光灯。
BENTLY 330180-90-05通道温度模块系统重置后，EPROM映射到默认值地址为$00000到$FFFFF，可以映射到如果需要，从$FF800000到$FF8FFFFF。之间的控制映射EPROM/闪存混合模式和所有闪存模式由外部板跳线J8和VMEchip2位的组合GPIO2。表4-1显示了“闪存”跳线和GPIO位2的方式更改EPROM/闪存配置SRAM允许调试器操作并限制诊断在没有DRAM夹层的情况下执行。SRAM不会支持突发循环。SRAM由VMEchip2控制，访问时间可编程。请参阅中的VMEchip2有关更多详细信息，请参阅单板计算机程序员参考指南。这些板上安装了100个ns SRAM。MVME177上可选提供SRAM备用电池。这个电池备份功能由Dallas DS1210S提供。只有一个MVME177支持备用电源。电池当主电源断开时，向SRAM提供VCC。每次MVME177通电时，DS1210都会检查电源。如果备用电源的电压低于2伏，第二个存储周期被阻塞。这允许软件提供早期警告，以避免数据丢失。因为DS1210可能会阻塞第二次访问，软件应至少做两次在依赖数据之前访问。MVME177可选提供跳线，允许电源连接到VMEbus+5 V STDBY引脚的DS1210源或车载电池。SRAM的可选电源为插座式三洋CR2430电池。提供一个小电容器以允许电池在不丢失数据的情况下快速更换。电池的寿命在很大程度上取决于环境电路板温度和通电占空比。FB1225CR2430锂电池应提供至少两年的电路板断电且电路板温度为40°C时的备份时间。如果通电占空比为50%（电路板通电一半电池寿命为四年。在较低的环境温度下温度备份时间大大延长，可能接近电池的保质期。
The EPROMs as shipped are normally used for the onboard
debugger firmware (177Bug), but could be used to download user
code to Flash. The EPROMs make up only 1MB of memory, but can
share the first 2MB of space with the first 2MB of Flash. The
EPROMs occupy only 1MB space in the ROM space in mixed mode
and will be repeated in the second 1MB space (which is reserved for
future expansion). The EPROMs could coexist with this 2MB of
Flash, or could be used to program all 4MB of Flash, then the J8
jumper could be removed to make only Flash available.
After a system reset, the EPROMs are mapped to the default
addresses $00000 through $FFFFF, and could be mapped to
$FF800000 through $FF8FFFFF if needed. The control between
mapping EPROM/Flash mixed mode and all Flash mode is done by
the combination of external board jumper J8 and the VMEchip2 bit
GPIO2. Table 4-1 shows how the “Flash” jumper and GPIO bit 2
change the EPROM/Flash configurationThe SRAM allows the debugger to operate and limited diagnostics
to be executed without the DRAM mezzanine. The SRAM will not
support burst cycles. The SRAM is controlled by the VMEchip2,
and the access time is programmable. Refer to the VMEchip2 in the
Single Board Computers Programmer's Reference Guide for more detail.
The boards are populated with 100 ns SRAMs.
SRAM battery backup is optionally available on the MVME177. The
battery backup function is provided by a Dallas DS1210S. Only one
backup power source is supported on the MVME177. The battery
supplies VCC to the SRAMs when main power is removed.
Each time the MVME177 is powered up, the DS1210S checks the
power source. If the voltage of the backup source is less than two
volts, the second memory cycle is blocked. This allows software to provide an early warning to avoid data loss. Because the DS1210S
may block the second access, the software should do at least two
accesses before relying on the data.
Optionally, the MVME177 provides jumpers that allow the power
source of the DS1210S to connect to the VMEbus +5 V STDBY pin
or the onboard battery.
The optional power source for the SRAM is a socketed Sanyo
CR2430 battery. A small capacitor is provided to allow the battery
to be quickly replaced without data loss.
The lifetime of the battery is very dependent on the ambient
temperature of the board and the power-on duty cycle. The FB1225
and CR2430 lithium batteries should provide at least two years of
backup time with the board powered off and the board at 40˚ C. If
the power-on duty cycle is 50% (the board is powered on half of the
time), the battery lifetime is four years. At lower ambient
temperatures the backup time is greatly extended and may
approach the shelf life of the battery.
