POWER MANAGEMENT
SECTION 14
Page 14-1 RPC -320
DESCRIPTION
There are thr ee power mana gement modes. Each mode
affects the way RPBASIC operates. T he
IDLE
command is used to control how the card operates
Default mode is full power. All commands, timers, and
interrupts function.
IDLE
command is not used.
There are a number of ways to exit the
IDLE
mode in
conjunction with ONITR. Refer to
Chapter 12, External
Interrupt
and
Chapter 13, Multi-mode Counter
for ways
to generate interr upts.
IDLE 2
is restricted on the type
of interrupt. T he signal at P2-INT must return to a high
state befor e the next
IDLE 2
command is executed. (P2-
INT is also controlled by the multi-mode counter and
optically isolated interrupt, described in Cha pter 12 and
13.) If it does not go high,
IDLE 2
mode w ill exit in
approximately 3 ms. This is due to a characteristic of
t he A 6 m a s k r e v is io n in th e D al la s 80 C 3 20 C P U . A
g e ne r a l r u le is to k ee p th e ne g at iv e pu ls e at P 2- I N T
greater than 50 ns but less than 3 ms.
IDLE
or
IDLE 0
waits until an ONTICK or ONITR
interr upt occur s. Se rial I/ O oper ates norm ally. U se this
comm and whe n you wan t your pr ogram to "hang out"
until something happens. The RPC-320 operates under
full power.
IDLE 1
reduce s power by 30% . H ere the C PU " shuts
down" but the internal timers are still operating.
ONT ICK and ON ITR will cause the card to come out of
power down m ode. Howe ver, the RS-232 se rial por ts
are disabled. C haracters in the transmitter buffer are not
sent out and incoming characters are ignored.
IDLE 2
is the lowest power mode. T he CPU, internal
timers , ser ial ports, and oscillator are tur ned off. Only
interrupts responding to ONITR wake up the processor.
Cur rent cons umption is less than 5 ma with no signals
going into or coming from the RPC -320.
IDLE 2
also has a number of operating restr ictions.
This mode shuts dow n the RS-232 rece iver/dr iver IC, so
no character s can come in or go out. T his IC also
supplies current for the amplifiers and analog to digital
converter. Do not apply negative voltages to the analog
input in this mode. The tick timer is shut off. However,
the real tim e clock m odule, if installed, continues to
operate.
NOTE:
The RS-232 receiver is shut down in IDLE
modes 1 and 2. A ny characters sent to the
RPC-320 dur ing this time are ignored or
grossly distorted.
NOTE:
Delay printing out the R S-232 ports for at least
20 ms (20 instructions) after exiting IDLE 1 or
IDLE 2. These chips generate RS-232 voltages
and require a "pow er up" time. Failure to do
so could result in garbled ch aracters.
NOTE:
The < Ctl> -C break char acter is not
recognized in
any
of the IDLE modes.
Norm ally this is not a problem except during
progr am deve lopment. If the prog ram is
executing an IDLE statement and it won' t
respond to any interrupts, pressing the reset
button is the only w ay to exit.
Exit
IDLE 2
b y ap p ly in g a l ow g oi ng p ul se a t t he I N T
i np u t a t P 2 . T h e p u ls e wi dt h s h ou ld b e 5 0 ns m in im u m .
The other
IDLE
modes re quire a pulse width of at least
1 micro-second. Optical interrupt ISOA/B may also be
used to exit any of the
IDLE
modes. The pulse w idth
needs to be at least 10 micr o-seconds.
FURTHER POWER REDUCTION
Some applications require the least amount of power
possible. You m ay rem ove cer tain IC' s from the card to
do this. The table below lists the IC 'U' number,
approximate curr ent consumption (in shutdown and run
mode), and function.
U n
Curr ent
Function
Run
Shutdown
U 9
1 0 m A
400 uA RS-485 interface
U14
100 uA
1 . 2 m a Reference for U 15,
temperature reference.
U15
5 m a
10 uA
Analog to digital
converter
U11
1 0 m A
1 ua
Digital I/O at J3
U17
1 0 m A
1 ua
Display output, keypad
scanner.
U 8
3 0 m A
10 uA
RS-232 driver/receiver,
power supply for analog
to digital converter,
amplifiers