POWER MANAGEMENT SECTION 14
Page 14-1 RPC-320
DESCRIPTION
There are three power management modes. Each mode
affects the way RPBASIC operates. The 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 interrupts. IDLE 2 is restricted on the type
of interrupt. The signal at P2-INT must return to a high
state before the next IDLE 2 command is executed. (P2-
INT is also controlled by the multi-mode counter and
optically isolated interrupt, described in Chapter 12 and
13.) If it does not go high, IDLE 2 mode will exit in
approximately 3 ms. This is due to a characteristic of
the A6 mask revision in the Dallas 80C320 CPU. A
general rule is to keep the negative pulse at P2-INT
greater than 50 ns but less than 3 ms.
IDLE or IDLE 0 waits until an ONTICK or ONITR
interrupt occurs. Serial I/O operates norm ally. Use this
command when you want your pr ogram to "hang out"
until something happens. The RPC-320 operates under
full power.
IDLE 1 reduces power by 30% . H ere the CPU " shuts
down" but the internal timers are still operating.
ONTICK and ONITR will cause the card to come out of
power down m ode. However, the RS-232 serial ports
are disabled. Characters in the transmitter buffer are not
sent out and incoming characters are ignored.
IDLE 2 is the lowest power mode. The CPU, internal
timers, ser ial ports, and oscillator are tur ned off. Only
interrupts responding to ONITR wake up the processor.
Current consumption 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 down the RS-232 rece iver/driver IC, so
no characters 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 time clock module, if installed, continues to
operate.
NOTE: The RS-232 receiver is shut down in IDLE
modes 1 and 2. Any characters sent to the
RPC-320 during this time are ignored or
grossly distorted.
NOTE: Delay printing out the RS-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 "power up" time. Failure to do
so could result in garbled characters.
NOTE: The < Ctl> -C break character is not
recognized in any of the IDLE modes.
Normally this is not a problem except during
program development. If the program is
executing an IDLE statement and it won' t
respond to any interrupts, pressing the reset
button is the only way to exit.
Exit IDLE 2 by applying a low going pulse at the INT
input at P2. The pulse width should be 50 ns minimum.
The other IDLE modes require 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 width
needs to be at least 10 micro-seconds.
FURTHER POWER REDUCTION
Some applications require the least amount of power
possible. You may rem ove certain IC' s from the card to
do this. The table below lists the IC 'U' number,
approximate current consumption (in shutdown and run
mode), and function.
Un Current Function
Run Shutdown
U9 10 mA 400 uA RS-485 interface
U14 100 uA 1.2 ma Reference for U15,
temperature reference.
U15 5 ma 10 uA Analog to digital
converter
U11 10 mA 1 ua Digital I/O at J3
U17 10 mA 1 ua Display output, keypad
scanner.
U8 30 mA 10 uA RS-232 driver/receiver,
power supply for analog
to digital converter,
amplifiers
