ET2799 Capstone presentation

ET2799 – CAPSTONEARDUINO-POWERED HALL-EFFECT TACHOMETER

MINH B. VUITT TECHNICAL INSTITUTE

086 GETZVILLE NEW YORK

2

AGENDA• Introduction• Project Overview

• Description• Project Cost & Schedule

• Details• Functionality• Input and Output• Design Challenges• Performance• Demonstration

• Unexpectations• Future• Questions

ET2799 Capstone – MAR 2015

ET2799 Capstone – MAR 2015 3

INTRODUCTION• Do-It-Yourself (DIY)

Tachometer built with:• Arduino Uno• Hall Effect Sensor • Thin Film Transistor (TFT) Liquid

Crystal Display (LCD)• w/ resistive touchscreen

functionality

• Designed for bicycle use Seeed Studio 2.8'' TFT Touch Shield V2.0

Arduino Uno R3 Prototyping Board


PROJECT OVERVIEW: DESCRIPTION• Based on an Arduino Uno R3 prototyping

board• Main sensor is a non-latching Hall Effect

Sensor• Output is a readout on the LCD:• Revolutions per Minute (RPM of wheels)• Calculated Speed (MPH)• Total Trip Distance (in miles; abbreviated as DST)


PROJECT OVERVIEW: DESCRIPTION


PROJECT OVERVIEW: COST & SCHEDULE

Item Price

Arduino Uno R3 ~$25

LCD Touchscreen ~$50

Hall Effect Sensor ~$2

10kΩ Resistor ~$1

0.01pF Ceramic Capacitor ~$1

Miscellaneous supplies ~$1

Total ~$80

Task Name Duration Start Finish

Select Project 5 days Mon 15-12-14 Fri 19-12-14

Research specifics 5 days Mon 22-12-14 Fri 26-12-14

Puchase/Wait on parts 5 days Mon 29-12-14 Fri 02-01-15

Coding/Testing 30 days Mon 05-01-15 Fri 13-02-15

Final Assembly 5 days Mon 16-02-15 Fri 20-02-15

Final Testing/Coding 5 days Mon 23-02-15 Fri 27-02-15

Presentation Creation 5 days Mon 02-03-15 Fri 06-03-15


DETAILS: FUNCTIONALITY • RPM measurement is extrapolated by

measuring times between Hall Effect sensor triggers• Speed measurement is determined by

multiplying RPM reading by the total wheel size (set for 29” wheels with 2.1” tires)• Distance measurement is simply number of

cycles (sensor triggers) multiplied by total wheel size.


DETAILS: I/O • Primary input is via a non-latching Hall Effect

Sensor to a digital input on the Arduino.• Non-latching is required so sensor triggers a

reading during each revolution.

• Output is to a LCD screen displaying RPM, speed in MPH, and distance traveled.• Readout are volatile!• Not saved between power cycles.


DETAILS: CHALLENGES• Original sample code:

• Had screen refresh and measurement calculations done in lockstep

• Did not zero reading with no input (i.e. not moving)

• Custom code:• Allows screen refresh and measurement calculations to

be semi-independent• Zeros readouts (RPM/MPH) in a “stopped” state• Contains extra lines in interrupt code to facilitate the

above


DETAILS: CODE SAMPLEdelay(50);

redrawElapse = millis() - lastRedraw;

if(redrawElapse > 1000)

Tft.drawString("RPM:",0,0,3,WHITE);

Tft.drawString("MPH:",0,30,3,WHITE);

Tft.drawString("DST:",0,60,3,WHITE);

Tft.fillRectangle(70,0,170,90,BLACK);

Tft.drawFloat(rpm,80,0,3,CYAN);

Tft.drawFloat(mph,80,30,3,CYAN);

Tft.drawFloat(distMiles,80,60,3,CYAN);

lastRedraw = millis();


DETAILS: PERFORMANCE• Display refresh @ ~1 Hertz• Reading updated once per second.• Adjustable in code.

• Functional down to ~0.5 RPM• Readings below a consistent 0.5 RPM fluctuate due to

code used for zeroing readout when stopped.• 0.5 RPM threshold is from 2 second delay to be

considered in a “stopped” state – adjustable in code.

• Distance measurement independent of speed and RPM measurements


DETAILS: DEMONSTRATION

Initial ON “Speed” Increase 1

Simulated “Stop” (Zeroing) “Speed” Increase 2


UNEXPECTATIONS• Positives• Coding based on C• Lower learning curve

• Negatives• Code complexity• High ambitions

• Project scope reduced• Touchscreen feature unused• Volatile Data• No customizable settings


FUTURE• Clean & Optimize Code:• Unused commented code• Better/streamlined functions

• Expand Features & Functionality:• Interaction via Touchscreen• Data Retention & Recall• Custom Settings

• Finalize a “Product”:• Enclosure with power supply


QUESTIONS

ET2799 Capstone presentation

Documents

Transcript of ET2799 Capstone presentation