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CALENDAR/CLOCK CHAPTER 7

7-8

CHAPTER SYNOPSIS

 Initializing and using the RTC

 Y2K and Y2.4K issues

 Using clock interr upts

DESCRIPTION

CALENDAR/CLOCK CHAPTER 7

The RPC -2350 has a battery backed Calendar/clock.

When used in conjunction with the DATE$ and TIME$

commands, the current date and time can be set and

read. It is accurate to 1 minute/month at 25°C and is not

adjustable.

The clock data sheet is in the applications disk. See

RTC72412.PDF.

SETTING DATE AND TIME

The clock must be turned on before it is used. This need

be done only once. To turn on the clock, type:

CONFIG CLOCK 1

The date and time can be set while running a program or

in the immediate mode. Date and time are treated as

strings and not numbers. To set the date and time:

date$="04-19-99"

time$="13:56:00"

To retrieve date and time as part of a program:

2000 DA$ = DATE$(0)

2010 TI$ = TIME$(0)

You can also print the d ate and time in the immediate

mode:

pr time$(0)

13:56:03

YEAR 2000 AND BEYOND

The clock on the RPC-2350G is year 2000 compliant

under the following condition:

Date is always returned as the last two digits of the

year. The first two digits, “19" or “20" must be

programm ed into your system. As of the time this

manual was written, this required a quick check on

the year. If it w as not “ 99", then you assum ed it

was some time in the 20' s.

The clock will roll over on December 31, 1999 at

23:59: 59 to January 1, 2000 with no problem s.

CAM BASIC operating system does not use or need any

real time clock values for its operation. A clock is not

needed in order for CAMBASIC to operate.

The clock compensates for leap year in 2000. Should

you expect this produc t to work into the 22nd century, it

will add a leap day in the year 2100 also. This, of

course, is not supposed to happen until the year 2400. If

you think your program will be working in the year

2100, you will have to compensate for this by resetting

the date when read as February 29, 2100 to M arch 1,

2100.

CLOCK INTERRUPTS

The RT C may be program med to generate interrupts at 1

second, 1 minute, or 1 hour intervals. L onger interrupt

intervals are convenient especially when ON TICK

interrupts are running.

An interrupt is generated when the real time clock

counters increment the unit of time selected for the

interrupt interval. Most of the time, the first interrupt

will be shorter than the interval period selected. For

example, suppose you want to interrupt every minute. If

the real time clock' s seconds were at 45 , the fir st

interrupt will occur in 15 seconds. Interrupts will then

occur every m inute. Operation is similar for hour ly

interrupts.

The clock is progr amm ed to interr upt at specific

intervals in software. See CLOCK1.BA S for example

program.

Jumper W 10 to enable interrupts.

1 2 ... 36 37 38 39 40 41 42 43 44 45 46 ... 82 83

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