Code<\/h2>\n\/* Double Transducer: RPM to Magnetism \r\nGia Marino and Freda Su\r\n\r\nOur code takes inputs from a rotary encoder and translates them to positions on a \r\ntiny circle in the encoder. We used these positions to calculate the RPM based on \r\nthe number of ticks that go by. Then we take that number and map RPM into a \r\n0 to 255 so that the LED can change brightness based on the rotation speed. Then we \r\nhave the photoresistor that reads the brightness of the LED and maps it into a range\r\nof 0 to 255 so it can send a voltage to our electromagnet. Lastly, the code takes the\r\nRPM, LED input value, LED brightness, and input value into the electromagnet and maps\r\nit into a range of 0-99. then prints it on the LCD screen\r\n\r\n Arduino pin | role | description\r\n ------------|--------|-------------\r\n A3 input photoresistor pin\r\n 9 output electromagnet pin\r\n 6 output LED pin\r\n 2 input rotary encoder pin A\r\n 3 input rotary encoder pin B\r\n SDA output LCD serial pin\r\n SCL input LCD clock pin\r\n GND input ground\r\n 5V output 5v\r\n\r\nWe based our if statement for the rotary encoder around Paul Stoffregen's Encoder\r\nlibrary code: https:\/\/github.com\/PaulStoffregen\/Encoderthe, specifically the \"basic\" \r\nexample that comes with the library. We had a lot of assistance and influence from Remy's \r\ncode for the LCD display (https:\/\/github.com\/remyfrank01\/Double-Transducer\/blob\/main\/DOUBLE_TRANS.ino).\r\nLastly, we copied the LCD tutorial code and worked off of that, so our code for the LCD display \r\nis also heavily influenced by this tutorial: https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/tutorials\/I2C-lcd*\/\r\n\r\n\r\n\r\n#include <LiquidCrystal_I2C.h> \/\/\/\/https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/tutorials\/I2C-lcd\r\n#include <Wire.h> \/\/LCD display\r\n#include <Encoder.h> \/\/https:\/\/www.pjrc.com\/teensy\/td_libs_Encoder.html\r\n\r\nconst int PHOTOPIN = A3; \/\/ photoresistor pin\r\nconst int LEDPIN = 6; \/\/ LED pin\r\nconst int EMPIN = 9; \/\/ electromagnet pin\r\nconst int totalTicks = 48; \/\/ amount of steps in one full rotation of the rotary encoder\r\nconst double anglePerTick = 1.0\/totalTicks; \/\/ one Rotation\/total ticks\r\n\r\n\/* Create an LCD display object called \"lcd\" with I2C address 0x27\r\n which is 16 columns wide and 3 rows tall. You can use any name you'd like. (col, row)\r\n (0,0) (1,0) (2,0) ... (15,0)\r\n (0,1) (1,1) (2,1) ... (15,1)*\/\r\nLiquidCrystal_I2C lcd(0x27, 16, 2);\r\nEncoder myEnc(2,3); \/\/pins 2 & 3 should have interrupt capablility\r\n\r\nvoid setup() {\r\n pinMode(PHOTOPIN, INPUT);\r\n pinMode(LEDPIN, OUTPUT);\r\n pinMode(EMPIN, OUTPUT);\r\n Serial.begin(9600);\r\n Wire.begin();\r\n \r\n \/\/ initialize the lcd (only need to do this once)\r\n lcd.init();\r\n\r\n \/\/ turn on the backlight to start\r\n lcd.backlight();\r\n lcd.clear();\r\n\r\n}\r\n\r\nunsigned long time0 = millis(); \/\/ time since last checked the rotary encoder\r\nunsigned long timerLCD = millis(); \/\/ timer used for LCD dispkay\r\nlong oldPosition = -999;\r\nfloat angVel; \/\/ anglular velocity\r\nunsigned int brightness = 0; \/\/the input for the LED that controls the brightness\r\nunsigned int photoVal = 0; \/\/ the value we get from the photoresistor\r\nunsigned int voltage = 0; \/\/ electromagnet voltage\r\nunsigned int rpm = 0; \/\/ rotations per min calculated from rotary encoder steps\r\n\r\n\r\nvoid loop() {\r\n\r\nunsigned long globalTime = millis(); \r\n \r\n long newPosition = myEnc.read();\r\n\r\n \/\/ convert ticks to rpm\r\n if (globalTime - time0 >= 1) { \/\/ checks every second\r\n double countTicks = abs(newPosition - oldPosition); \/\/ figures out how many steps passed by \r\n oldPosition = newPosition;\r\n\r\n \/\/ reset time so when loop runs again we base our math on the most recent last position\r\n time0 = globalTime; \r\n\r\n angVel = countTicks * anglePerTick;\r\n rpm = angVel * 60000; \/\/ converts just calculated angular velocity to RPM\r\n }\r\n\r\n \/\/ takes RPM and calculates a mapped output voltage so brightness is affected by rpm speed\r\n brightness = map(rpm, 0, 60, 0, 255); \/\/120-360 deg\/sec to 0-255 analogWrite\r\n analogWrite(LEDPIN, brightness);\r\n\r\n \/\/takes photoresistor value and maps an output voltage for the electromagnet so\r\n \/\/ it varies based on the photoresistor values\r\n photoVal = analogRead(PHOTOPIN);\r\n voltage = map(photoVal, 0,1023, 0, 255); \/\/adjust photoVal range: 0-1023 photoVal to 0-255 analogWrite\r\n analogWrite(EMPIN, voltage);\r\n\r\n \/\/LCD display\r\n \r\n if (millis() - timerLCD >= 250) {\/\/ every 1\/4 sec\r\n timerLCD = millis(); \/\/reset\r\n lcd.clear();\r\n \/\/ set cursor to home position, i.e. the upper left corner\r\n lcd.home(); \r\n int mappedRPM = map(rpm, 0, 60, 0, 99);\r\n if (mappedRPM > 99) mappedRPM = 99;\r\n else if (mappedRPM < 0) mappedRPM = 0;\r\n lcd.print(\"i:\" + String(mappedRPM)); \/\/convert to rpm\r\n\r\n lcd.setCursor(6,0); \/\/middle of first row\r\n int mappedBrightness = map(brightness, 0, 255, 0, 99);\r\n if (mappedBrightness > 99) mappedBrightness = 99;\r\n else if (mappedBrightness < 0) mappedBrightness = 0;\r\n lcd.print(\"m:\" + String(mappedBrightness)); \/\/convert brightness\r\n \/\/ move cursor to column 8, row 1\r\n \r\n lcd.setCursor(8, 1);\r\n int mappedPhotoVal = map(photoVal, 0, 1023, 0, 99);\r\n if (mappedPhotoVal > 99) mappedPhotoVal = 99;\r\n else if (mappedPhotoVal < 0) mappedPhotoVal = 0;\r\n \r\n lcd.print(String(mappedPhotoVal));\r\n \/\/ move cursor to column 13, row 2\r\n lcd.setCursor(12, 1);\r\n\r\n int mappedVoltage = map(voltage, 0, 255, 0, 99);\r\n if (mappedVoltage > 99) mappedVoltage = 99;\r\n else if (mappedVoltage < 0) mappedVoltage = 0;\r\n lcd.print(\"o:\" + String(voltage));\r\n }\r\n\r\n \/\/goes to RC circuit, transistor etc\r\n\r\n}<\/pre>\n <\/p>\n","protected":false},"excerpt":{"rendered":"
by Gia Marino and Freda Su Overall Photos Pictures of Each Part and Videos Videos: Simple Narrative Description The knob measures how fast it\u2019s spinning. This controls…<\/p>\n","protected":false},"author":236,"featured_media":16326,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[86],"tags":[],"_links":{"self":[{"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/posts\/16294"}],"collection":[{"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/users\/236"}],"replies":[{"embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/comments?post=16294"}],"version-history":[{"count":13,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/posts\/16294\/revisions"}],"predecessor-version":[{"id":16337,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/posts\/16294\/revisions\/16337"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/media\/16326"}],"wp:attachment":[{"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/media?parent=16294"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/categories?post=16294"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/courses.ideate.cmu.edu\/60-223\/f2022\/work\/wp-json\/wp\/v2\/tags?post=16294"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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