Smart Automated Medicine Dispenser

#include <Arduino.h>
#include <Wire.h>
#include <Servo.h>
#include <Keypad.h>
#include <LiquidCrystal_I2C.h>
const byte SERVO_PIN=10, BUZZER_PIN=11, GREEN_PIN=A0, RED_PIN=A1;
// Calibration required with an empty tray. Four forward indexes within 180 degrees.
const byte POSITIONS[]={0,45,90,135,180};
char keys[4][4]={{'1','2','3','A'},{'4','5','6','B'},{'7','8','9','C'},{'*','0','#','D'}};
byte rows[]={2,3,4,5}, cols[]={6,7,8,9};
Keypad pad(makeKeymap(keys),rows,cols,4,4);
LiquidCrystal_I2C lcd(0x27,16,2);
Servo tray;
enum State {SET_UNIT,SET_VALUE,CONFIRM,RUNNING,PAUSED,MOVING,FINISHED,HOMING};
State state=SET_UNIT;
uint32_t value=0, multiplier=1, interval=0, remaining=0, tick=0, actionAt=0;
byte count=0; char unit='s';
char previous[2][17]={{0},{0}};
void line(byte row,const char* text) {
 char out[17]; memset(out,' ',16); out[16]=0;
 for(byte i=0;i<16 && text[i];i++) out[i]=text[i];
 if(strcmp(previous[row],out)) {lcd.setCursor(0,row);lcd.print(out);strcpy(previous[row],out);}
}
void show() {
 char a[32],b[32];
 switch(state) {
 case SET_UNIT: line(0,"Select time unit");line(1,"1:sec 2:min 3:hr");break;
 case SET_VALUE: snprintf(a,sizeof(a),"Interval: %lu %c",(unsigned long)value,unit);line(0,a);line(1,"#:OK *:erase");break;
 case CONFIRM: snprintf(a,sizeof(a),"Every %lu %c",(unsigned long)value,unit);line(0,a);line(1,"A:start D:cancel");break;
 case RUNNING: case PAUSED:
 snprintf(a,sizeof(a),"%s %lu s",state==PAUSED?"Paused":"Left",(unsigned long)((remaining+999)/1000));
 snprintf(b,sizeof(b),"%u/4 B:pause D:end",count);line(0,a);line(1,b);break;
 case MOVING: snprintf(a,sizeof(a),"Tray step %u/4",count);line(0,a);line(1,"D:cancel");break;
 case FINISHED:line(0,"Session complete");line(1,"Returning home");break;
 case HOMING:line(0,"Cancelled");line(1,"Returning home");break;
 }
}
void home(uint32_t now) {
 noTone(BUZZER_PIN);digitalWrite(GREEN_PIN,LOW);digitalWrite(RED_PIN,LOW);
 tray.write(POSITIONS[0]);state=HOMING;actionAt=now;
}
void setup() {
 pinMode(GREEN_PIN,OUTPUT);pinMode(RED_PIN,OUTPUT);pinMode(BUZZER_PIN,OUTPUT);
 Serial.begin(9600);Wire.begin();lcd.init();lcd.backlight();
 tray.write(POSITIONS[0]);tray.attach(SERVO_PIN,500,2500);
 Serial.println(F("DEMO ONLY: verify empty tray travel; no delivery or jam sensor."));show();
}
void loop() {
 uint32_t now=millis(),elapsed=now-tick;tick=now;
 if(state==RUNNING) remaining=elapsed>=remaining?0:remaining-elapsed;
 char k=pad.getKey();
 if(k=='D' && state!=HOMING) home(now);
 else if(state==SET_UNIT && k>='1' && k<='3') {
 multiplier=k=='1'?1:(k=='2'?60:3600);unit=k=='1'?'s':(k=='2'?'m':'h');value=0;state=SET_VALUE;
 } else if(state==SET_VALUE) {
 if(k>='0' && k<='9') {uint32_t next=value*10+(k-'0');if(next<=86400UL/multiplier)value=next;}
 if(k=='*')value/=10;
 if(k=='#' && value) {interval=value*multiplier*1000UL;state=CONFIRM;}
 } else if(state==CONFIRM && k=='A') {count=0;remaining=interval;state=RUNNING;}
 else if(state==RUNNING && k=='B')state=PAUSED;
 else if(state==PAUSED && k=='B')state=RUNNING;
 if(state==RUNNING && remaining==0) {
 ++count;tray.write(POSITIONS[count]);state=MOVING;actionAt=now;tone(BUZZER_PIN,2200,200);
 }
 if(state==MOVING) {
 digitalWrite(GREEN_PIN,((now-actionAt)/200)%2==0);
 if(now-actionAt>=1500) {
 digitalWrite(GREEN_PIN,LOW);
 if(count==4) {tray.write(POSITIONS[0]);state=FINISHED;actionAt=now;}
 else {remaining=interval;state=RUNNING;}
 }
 }
 if(state==FINISHED) {
 bool on=((now-actionAt)/250)%2==0;digitalWrite(RED_PIN,on);
 if(on)tone(BUZZER_PIN,3000);else noTone(BUZZER_PIN);
 if(now-actionAt>=3000) {noTone(BUZZER_PIN);digitalWrite(RED_PIN,LOW);state=SET_UNIT;}
 }
 if(state==HOMING && now-actionAt>=1500)state=SET_UNIT;
 show();
}