Cookie dispenser: four-LED interface

4 LEDs = tiny vocabulary, no serial monitor needed. patterns should make sense without a decoder ring... save for later: blink rhythm vs color, esp if the colors are hard to tell apart

problem: the original interaction depends on reading the serial monitor. A standalone user needs an indication of which input the program expects and whether an action has finished.

Four-LED redesign and userOutputOn helper.

LED pin writes, userOutputOff and an example pattern.

implementation in the redesign: userOutputOn(one, two, three, four) writes four binary indicators to Arduino pins 4, 5, 6 and 7. userOutputOff() sets all four pins LOW. Calls are inserted at the relevant interaction states; the report gives this example:

userOutputOn(1, 1, 1, 1); // example pattern: all four LEDs on
userOutputOff();

reference location: “Redesign, Testing, and Evaluation → Additions to the Design”; the complete helper implementation is in that section.

review questions: Make an explicit state-to-pattern table for enrollment, waiting, recognized fingerprint, allowance used and error. Are patterns understandable without the serial monitor? The report’s later improvement list proposes a screen for more specific instructions.