Power Warning

When HUNTER’S batteries become exhausted a power warning message will appear on the screen. Normal operation will continue, but keyboard entries will be punctuated by warning tones and repetition of the power warning message until the battery state is rectified either by replacement of primary cells or recharging of Nickel-Cadmium cells, if installed.

Eventually, if the warnings are ignored, HUNTER will shut down and refuse to operate further.

Every HUNTER has to pass a stringent operating test in this low power regime. However, it is strongly recommended that operator training procedures and user programs are structured to avoid continued operation when warnings become persistent, especially when rechargeable cells are used.

The power warning sequence may be misleading if RS-232 communications are used infrequently. When HUNTER’S communications system is activated power drain increases significantly. This increase can cause the power warning stage to be missed altogether, and instead cause HUNTER to shut down without warning.

While this is not hazardous, it can be very confusing for an operator who does not know what is wrong. Because of this it is recommended that user programs with infrequent communication requirements use a test routine. This activates the communications package, and then tests the power state before restoring HUNTER to normal. This routine is used at the start of every data entry sequence.

If batteries become exhausted whilst communications are in progress, then normal power warning messages will appear once the keyboard operation is resumed.

Note

Power warning messages only occur when keyboard entries are in progress.

Sample Warning Subroutine

20 OUT 132,1
30 J=INP(2):OUT 132,0
40 IF J = 0 THEN RETURN
50 CLS
60 PRINT "PLEASE CHANGE MY BATTERIES!"
70 BEEP: BEEP: BEEP: BEEP
80 RETURN

This program operates as follows:

  1. The power status is available as bit 2 in HUNTER port 2.

    0 = power OK, 1 = Low Power state.

  2. Line 20 energises the RS-232 serial interface.

  3. Line 30 reads the power state from port 2, and then closes down the interface to conserve power.

  4. Line 40 checks the power status bit.

  5. Line 50-80 Display a warning and ring HUNTER’S bell!