Power Management

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 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 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

SECTION 14

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 by applying a low going pulse at the INT input at P2 . The pulse width should be 50 ns minimum . 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.

Un		Curr ent			Function
	Run		Shutdown
U9	10	mA		400 uA RS-485 interface
U14	100 uA			1 . 2 ma	Reference for U 15,
					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

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