Page 314 - Embedded Microprocessor Systems Real World Design

(Update display)
Turn all displays off
INCR DISPLY.
If DISPLY = 4, DISPLY = 3 (DISPLY counts 0-3).
If MODE = 0 (Powerfail),
If BLFLAG (Time to blink display),
If DISPLY = 0, convert minutes ones to 7-seg and write to display reg.
If DISPLY = 1, convert minutes tens to 7-seg and write to display reg.
If DISPLY = 2, convert hours ones to 7-seg and write to display reg.
If DISPLY = 3, convert hours tens to 7-seg and write to display reg.
If MODE = 1 (normal timekeeping),
If override time = 0:O (OVHOUR = OVMIN = 01,
If DISPLY = 0, convert minutes ones to 7-seg and write to display reg.
If DISPLY = 1, convert minutes tens to 7-seg and write to display reg.
If DISPLY = 2, convert hours ones to 7-seg and write to display reg.
If DISPLY = 3, convert hours tens to 7-seg and write to display reg.
Else (Override time was > O:O),
If DISPLY = 0, convert OVMIN ones to 7-seg and write to display reg.
If DISPLY = 1, convert OVMIN tens to 7-seg and write to display reg.
If DISPLY = 2, convert OVHOUR ones to 7-seg and write to display reg.
If DISPLY = 3, convert OVHOUR tens to 7-seg and write to display reg.
If MODE = 2 (time set),
If DISPLY = 0, convert PRMIN ones to 7-seg and write to display reg.
If DISPLY = 1, convert PRMIN tens to 7-seg and write to display reg.
If DISPLY = 2, convert PRHOUR ones to 7-seg and write to display reg.
If DISPLY = 3, convert PRHOUR tens to 7-seg and write to display reg.
(Now update the discrete status LEDs.)
If MODE = 0 or 1 (Powerfail or normal timekeeping),
Turn off SET LED.
If ONOFF (Timing ON time)
OR if OVTIME > 0 and VOFLAcf set (ON override),
If not MTI?L,AG Water level OK),
Turn on ON/OFF LED.
Else (MTFLAG set, water level low),
If BLF’LAG, Turn on ON/OFF LED (Makes LED blink).
If not ONOFF
OR if not VOFLAG, turn off ON/OFF LED.
If MODE = 2 (time set),
Turn on SET LED.
If SEMODE = 1,
If not MTFLAG Water level OK),
Turn on QN/OFF LED.
Else (MTFLA(3 set, water level low),
If BLFLAG, Turn on ON/OW LED (Makes LED blink).
If SEMODE = 0, turn off ON/OFF LED.

Appendix A 295