Pill Dispenser Alarm

Overview

This project is inspired by a tip my friend gave me when I got diagnosed with ADHD a few years ago and started taking medication. This advice was to try to take ADHD medication at the same time every day, regardless of your schedule, to avoid interfering with your sleep. I have seen benefits following this advice for short periods of time, but doing anything consistently is quite difficult as a college student. This project is designed to force taking my medication to be the first thing I do every day, even if I decide to go back to bed after taking it. At a pre-determined time each day, a single pill is released from the pill dispenser onto a load cell bar as an alarm sounds. When, and only when, that pill is lifted (or a safety timeout mechanism is triggered), the alarm will stop. The main components of this project include a pill box carousel, a stepper motor, a load cell bar, and a buzzer. 

Process

Discussion

While I was not in class for critique, I can anticipate a few potential questions and comments my classmates would have had. Firstly, I can imagine that at least a few of my classmates take a daily medication similar to mine, and I hope those classmates would have imagined themselves using this device. Second, I likely would have received a question along the lines of: "What would happen if you accidentally skipped a slot when refilling the carousel?" While this is not implemented in the current project, I would ideally like the machine to keep turning 15° every few seconds until either a pill falls or the device determines there are no more pills left to dispense. Lastly, I hypothesize that I could've been asked a question like: "What would happen if a user wanted to retrieve a pill while the machine is off or in between active periods?" Due to the size and shape of the pill slots in the current design, the easiest way to remove pills is to flip the device upside down, which is certainly a design flaw. In a future iteration of the project, I would incorporate a lever or dial that can mechanically turn the carousel without the use of electricity. 

Upon personal reflection, this project taught me that I struggle greatly with methodically combining electrical components. My process of debugging often consisted of spending a few minutes on one component, getting frustrated, and moving on to another component. This process not only slowed my progress but also made it difficult for me to gauge how much work I had done and had left to do. Instead, I should have followed a unit-testing approach, by getting each component to work close to 100% before moving on to the next, an approach I already follow when programming Software. Secondly, I soldered my stepper motor driver and load cell bar amplifier way too early in the design process; it was only after I soldered all drivers and wires to a single board that I realized I needed to swap the protoboard type and replace a fried stepper motor driver. 

Prior to starting the project, I suspected that my strongest skill set would be my software programming. After completing the project, I can say that this is certainly true. While it took me slightly longer than I expected to program the stepper motor, debugging code feels much more linear to me than any hardware debugging.

Overall, I feel that I accomplished most of my overall goals for the project (except for timeliness!) and gave me confidence in my programming abilities. While I don't expect to build another iteration of the device, I plan on utilizing the skills I learned over the past few weeks in my final project. 

Technical information

/*

Written by: Allison Feldman (Andrew ID: abf2) for Project 2 of Carnegie Mellon course 60-223, "IDeATe Portal: Introduction to Physical Computing"

Project Name: Pill Dispenser Alarm

 This file contains code to program an Arduino Uno which is connected to a "Pill Dispenser Alarm" system.

   This system helps individuals take a particular medication at the same time every day by combining a pill dispenser and an alarm clock. At the time a pill is dispensed, a buzzer is turned on, which won't turn off until the dispensed pill has been taken.

The pins in use are:

   D2: an "output" pin that triggers the movement of a stepper motor.

   D3: an "output" pin that defines the direction of the stepper motor.

   D5: an "output" pin that powers a load cell bar amplifier.

   D6: an "input" pin that takes in data from the load cell bar amplifier.

   D8: an "output" pin that controls the state of a buzzer.

The program is currently in "demo" mode, meaning the length of a day is defined as 20,000 milliseconds, rather than capturing live time data to trigger pill releases.

*/

#include <AccelStepper.h>

#include <HX711.h>

#include <NTPClient.h>

#include <WiFi.h>

#include <WiFiUdp.h>

// Stepper Motor Pins

const int STEP_PIN = 2;

const int DIR_PIN = 3;

// Load Cell Bar Pins

const int LOADCELL_DOUT_PIN = 5;

const int LOADCELL_SCK_PIN = 6;

// Buzzer Pin

const int buzzerPin = 8;

// Variables related to the system's lifecycle. They keep track of how many pills (out of 30) have been dispensed, as well as whether or not loadCellBar detects stable (or unfluctuating) weight.

int pillsDispensed = 0;

bool isWeightStable = false;

// These thresholds determine whether a pill has dropped onto or removed from the load cell bar.

float minWeightThreshold = 0.1; // Min weight threshold to determine whether capsule has been dropped

float maxWeightThreshold = 0.04; // Max weight threshold to determine whether capsule has been removed

// Stepper Motor Logistics

const float stepsFor12Degrees = 53;

const float initialSpeed = 100;

const float initialAcceleration = 50;

const float normalSpeed = 600;

const float normalAcceleration = 100; 

const float homePosition = 56;

unsigned long cycleStartTime; // used as a safety mechanism to "time out" if the buzzer has been playing for more than 2 minutes.

unsigned long currentTime;

AccelStepper myMotor(1, STEP_PIN, DIR_PIN);

HX711 scale;

void setup(){

 Serial.begin(9600);

 pinMode(buzzerPin, OUTPUT);

  // Initialize the motor with a lower-than-nromal speed and acceleration to mitigate sudden movement

 myMotor.setMaxSpeed(initialSpeed);

 myMotor.setAcceleration(initialAcceleration);

 delay(2000);

 myMotor.moveTo(homePosition); // "Home, which is halfway between 2 slots

 while (myMotor.distanceToGo() != 0) {

   myMotor.run();

 }

 // Set speed and acceleration to normal

 myMotor.setMaxSpeed(normalSpeed);

 myMotor.setAcceleration(normalAcceleration);

 // Initialize the load cell bar

 scale.begin(LOADCELL_DOUT_PIN, LOADCELL_SCK_PIN);

 scale.set_scale(); 

 scale.tare();    

}

bool checkIfWeightStable() {

 while (isWeightStable == false) {

   float weights[100];

   float weightSum = 0;

   if (scale.get_units(10) > minWeightThreshold) {

     for (int i = 0; i < 100; i++) {

       float weight = scale.get_units(1);

       weights[i] = weight;

       weightSum += weight;

       delay(10);

     }

     float weightAverage = weightSum / 100;

     for (int j = 0; j < 100; j++) {

       if (abs(weightAverage - weights[j]) > 0.25) { // 0.25 grams

         return false;

       }

     }

     return true;

   }

 }

}

void pillCycle() {

 cycleStartTime = millis();

 currentTime = millis();

 tone(buzzerPin, 440); // start buzzer

 // Dispense 1 pill

 if (pillsDispensed == 0) {

   myMotor.move(stepsFor12Degrees / 2);

 } else {

   myMotor.move(stepsFor12Degrees);

 }

  while (myMotor.distanceToGo() != 0) {

   myMotor.run();

 }

 isWeightStable = false;

 // Wait for pill to drop onto load cell bar or for there to be a timeout

 while ((isWeightStable == false) && (currentTime - cycleStartTime < 120000)) {

   currentTime = millis();

   int weights[100];

   float weightSum = 0;

   if (scale.get_units(10) > minWeightThreshold) {

     isWeightStable = checkIfWeightStable();

   }

 }

 isWeightStable = false;

 pillsDispensed += 1;

 // Wait for pill to be removed from load cell bar or for there to be a timeout

 while ((isWeightStable == false) && (currentTime - cycleStartTime < 120000)) {

   currentTime = millis();

   isWeightStable = checkIfWeightStable();

 }

 // Assume pill has been taken or there has been a timeout

 noTone(buzzerPin); // Stop buzzing

}

void loop(){

 pillCycle();

 cycleStartTime = millis();

 if (pillsDispensed >= 30) {

   // Reset pills and prepare to refill dispensor

   pillsDispensed = 0;

   myMotor.moveTo(homePosition);

   while (myMotor.distanceToGo() != 0) {

     myMotor.run();

   }

 }

 Serial.println("Cycle complete");

 delay(20000);

}