Remote Processing RPC-2350 User Manual
Page 27
CHAPTER 5
DATA MEMORY
5-1
Figure 5-1 M emory location
CHAPTER SYNOPSIS
Battery backup description
Where and how to store va riables
Saving and retr ieving data from F lash
Installing 512K RAM
Discussion about cor rupted da ta
DESCRIPTION
DATA ME MORY CHAP TER 5
The RP C-2350 is usually installed w ith 128K of RA M in
socket U 2. A n optional 512K can be installed. RAM is
battery backed on bo th models.
This chapter discusses saving and retrieving variables
from RAM and Fla sh EP ROM and runn ing assem bly
language progr ams.
If program and data are battery backed, the UNNEW
c o m m an d m ay b e u s ed to tr y to r e st or e th e pr o g ra m .
Variables used by the Basic program are clear ed,
howeve r. Cer tain variab les are pr eserve d and data
POKEd into RA M is saved.
BATTERY BACKUP
Battery life is about 3 years (27,000 hours). See
additional information a few paragraphs below.
B a tt e ry B1 is u se d to b ac k up th e RA M a n d r e a l t im e
clock
The installed battery is rated for 190 mA-hours. RAM
(any size) typically requires 1-2 micro-am ps in standby.
The clock r equires typically 3 micro-amps. Assuming 7
micro-Amps of current draw, you could expect 3 years
life from the battery (assuming the board was off the
whole time.)
The problem with calculating battery life are variables
beyond our reasonable control. First, memory
manufacturers specify a ‘typical’ current of 1 to 2 micro-
amps and a maximum of 100 (high temperature
operation). Other factors affecting battery life include
o p er a ti ng te m p er a tu r e , cl oc k ch ip , a n d t im e th e RP C -
2350 has power applied to it. You can expect the battery
to last between 3 to 5 years for operation at 25°C. At
50°C, life is about half as much. This is due to battery
deterioration and CMOS leakage increases at higher
tempera tures.
Hum idity also affects ba ttery life. Very high humid ity
(in conjunction with a dirty environment) increases
leakage. Low hu midity dr ys out the batter y seal,
allowing contaminates to enter.
The point of this explanation is to give you the factors
affecting battery life. Under the best of conditions, life
is 7 years. Unde r worse conditions, it could be as low
as 3 months. You can add a larger battery as described
below.
Existing battery voltage is measured across W14.
Alternate battery
A larg er 3. 0V batter y can be installed by connectin g it to
W14. Be sure to remove the existing battery. Note the
polarity marked on the board.
STORING VARIABLES IN RAM
The term "var iables" in this context includes numb ers,
strings, arr ays, recipes, and formulas as applied to your
application.
CAMBASIC provides 26 “protected” variables, A%-
Z%, that are not erased on power up. These are
accessed like other BAS IC variables.
The Flash EP ROM may be used to store variables or
constants, such as text strings, to help reduce the size of
t he m a in p r og r a m .
CAM BASIC m emory map
T h e fo ll ow i ng d ia g r am i s a m e m or y m ap f or t he R P C -
2350.