Archived source flow
Technical notes
Entry and mode selection
checkPincode() collects keypad entry. A complete entry is compared with two stored codes to enable or disable the mode; an unmatched entry leaves the mode unchanged. The entry buffer is then reset.
Status paths
When the mode is enabled, the indicator is high and door, window and proximity readings can write status text. The disabled branch lowers the indicator. A gas-input display check follows outside the mode gate, while temperature messages go to Serial.
Material source limits
Integer division by 1023 occurs before multiplication by 5 in four input conversions; nominal readings from 0 to 1022 collapse to zero. Several writes share the same LCD row and can overwrite earlier messages. No siren output, calibrated measurement or validated alarm behaviour is established.