Motorola MBX Series, Installation And Use Manual

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NVRAM
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NVRAM
The MBX series embedded controller accommodates 32KB of Non-
Volatile RAM (NVRAM) in a 34-pin socket, XU2. A battery within the
device supplies VCC to the NVRAM when main power is removed. The
NVRAM provides for a low-battery indication which can be read by the
processor (via status register #2—see the MBX Programmer’s Reference
Guide).
The lifetime of the battery is very dependent on the ambient temperature
of the board and the power-on duty cycle. At 70
°
C, the worst-case elapsed
time for battery protection is seven years. Battery warning time is 24 hours
minimum. At lower ambient temperatures the backup time is greatly
extended.
The first 4K of the NVRAM contains the vital product data (VPD) and
should not be used. The remaining NVRAM is available for general use.
On-board Backup Battery
The on-board backup power source for the keep-alive power circuits is a
Sanyo CR14250SE lithium battery, socketed for easy removal and
replacement. A low-battery indication (via status register #2) allows you to
replace it before it discharges completely. When replacing the battery,
power must be applied to the board to prevent data loss.
The lifetime of the battery is very dependent on the ambient temperature
of the board and the power-on duty cycle. At 70
°
C, the worst-case elapsed
time for battery protection is four years. Battery warning time is 24 hours
minimum. At lower ambient temperatures the backup time is greatly
extended.
When a board is stored, the on-board battery should be disconnected to
prolong battery life. This is especially important at high ambient
temperatures.
The MBX board provides a “freshness seal” to protect the on-board battery
when it is not in use. The battery can be disconnected and the battery
freshness seal reset by removing the jumper from J1 pins 1 and 2 after