Session 6 John Wolf (WolfDenElectronics.com)

Objectives – We’ll Learn  Code to Voice  PIR sensors – motion detection  Quadrature Encoders  Audio to RGB Display  Use of Interrupts

Code to Voice  Emic2 board from Parallax  Uses the “SoftwareSerial” library to establish a UART serial port  No special library for the board  Commands are specific codes placed on the Serial Monitor send line  Voice speaks via audio out  Just type your message into sketch as a string within quotes

Emic 2 Text-to-Speech Module Arduino Rx Arduino Tx

#include #define rxPin 10 // Serial input (connects to Emic 2 SOUT) #define txPin 9 // Serial output (connects to Emic 2 SIN) #define ledPin 13 // on-board LED // set up a new serial port SoftwareSerial emicSerial = SoftwareSerial(rxPin, txPin); void setup() { Serial.begin(9600); pinMode(ledPin, OUTPUT); pinMode(rxPin, INPUT); pinMode(txPin, OUTPUT); emicSerial.begin(9600); digitalWrite(ledPin, LOW); Serial.print(“:”); // signals us to start }

// Serial Monitor: Newline, 9600 Baud. Type S first, then message void loop() { if (Serial.available()) emicSerial.write(Serial.read()); if (emicSerial.available()) Serial.write(emicSerial.read()); }

PIR (passive infrared sensor)  Detects motion via a special lens over IR sensor array  Monitors a single pin for a HIGH to do something in your sketch  We’ll turn on a speaker and play a tune!

Passive Infrared Sensor – motion detector

ULN2003 Darrington Pair Driver – 500ma with flyback diodes GND connection for all ULN2003

const int speakerPin = 9; // choose the pin for the speaker const int inputPin = 2; // choose the input pin for the PIR sensor int length = 15; // the number of notes char notes[] = "ccggaagffeeddc "; // a space represents a rest int beats[] = { 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 4 }; int tempo = 200; void playTone(int tone, int duration) { for (long i = 0; i < duration * 1000L; i += tone * 2) { digitalWrite(speakerPin, HIGH); delayMicroseconds(tone); digitalWrite(speakerPin, LOW); delayMicroseconds(tone); } } // end of playTone

void playNote(char note, int duration) { char names[] = { 'c', 'd', 'e', 'f', 'g', 'a', 'b', 'C' }; int tones[] = { 1915, 1700, 1519, 1432, 1275, 1136, 1014, 956 }; // play the tone corresponding to the note name for (int i = 0; i < 8; i++) { if (names[i] == note) { playTone(tones[i], duration); } }// end of playNote void setup() { pinMode(speakerPin, OUTPUT); pinMode(inputPin, INPUT); //delay(40000); // Move away and let detector go off }

void loop() { int val = digitalRead(inputPin); if (val == HIGH) { for (int i = 0; i < length; i++) { if (notes[i] == ' '){ delay(beats[i] * tempo); // rest } else { playNote(notes[i], beats[i] * tempo); }// end if-else statement delay(tempo / 2); }// end for statement }// if test for input }// end loop If movement is detected, the output pin goes HIGH. The software plays the song.

Quadrature Encoders  Looks like a potentiometer  Issues two square wave signal 90 degrees apart in phase called A and B  If A rises first, the knob has been turned one way  If B rises first, the know was turned the other way  You count the pulse of one or the other to count how far the knob was turned

Quadrature Encoder

Quadrature – meaning 90 degrees out of phase

Interrupts – real time control  Hardware sends signal asynchronously  Sketch is set to react by halting code, jumping to handler function, then jumping back to next instruction in normal flow of code  attachInterrupt(0,handler,RISING);  See pin-out diagram for interrupt pins  “handler” is a func you name  RISING is one of 5 signal sensing’s

Arduino Uno  int0 on pin 2, int1 on pin 3  Handler, or Interrupt Service Routine (ISR)  Void function with no return value  Can’t use delay() statement inside it  All variables used have to be typed “volatile” at the top of sketch  LOW,HIGH,RISING,FALLING,CHANGE  Nothing in the sketch tells you about interrupt accept the attachInterrupt() in the set up function. When it comes, the ISR just runs.

Precautions  The signal that triggers and interrupt must be stable – no bounce or false hits or the interrupt will trigger multiple times  Best to use Real Time Clock or millis() method for time delays or you could miss an interrupt. Delay() blocks the code while timing out.

volatile int encoder_a = 2; // interrupt on pin 2 volatile int encoder_b = 3; // interrupt on pin 3 volatile long encoder; void setup() { Serial.begin(115200); // encoder pin on interrupt 0 (pin 2) attachInterrupt(0, encoderPinChangeA, CHANGE); // encoder pin on interrupt 1 (pin 3) attachInterrupt(1, encoderPinChangeB, CHANGE); encoder = 0; } void loop() { // provide Processing with data and \n Serial.print(encoder); Serial.print('\n'); delay(10); // if you run too fast, Processing won’t see data }

//######## Interrupt Handlers ############# void encoderPinChangeA() { if (digitalRead(encoder_a)==digitalRead(encoder_b)) { encoder--; } else{ encoder++; } void encoderPinChangeB() { if (digitalRead(encoder_a) != digitalRead(encoder_b)) { encoder--; } else { encoder++; }

Use Processing for cool interface

import processing.serial.*; Serial myPort; int colla=0, omy=2, colla2=215, colla3=255, omy2=2, omy3=2; float cosx, siny; void setup(){ size(1080,700); myPort=new Serial(this,"COM17", ); myPort.bufferUntil('\n'); } void draw(){ } void serialEvent(Serial myPort){ background(0); String pulses_raw=myPort.readStringUntil('\n'); if(pulses_raw != null){ pulses_raw=trim(pulses_raw); float pulses = float(pulses_raw); pulses = pulses* /48; siny=sin(pulses); cosx=cos(pulses); stroke(colla,colla2,colla3); strokeWeight(10); fill(colla,colla2,colla3); // first two: center last two: end of line line(width/2, height/2, width/2+width/2*cosx, height/2+height/2*siny);

colla=colla+omy; if(colla>254) omy=omy* -1; if(colla<1) omy=omy* -1; colla2=colla2 + omy2; if(colla2>254) omy2=omy2* -1; if(colla2<1) omy2=omy2* -1; colla3=colla3 + omy3; if(colla3>254) omy3=omy3* -1; if(colla3<1) omy3=omy3* -1; } A bunch of color changes on the line

Audio to RGB  MSGEQ7 is a small chip that divides the audio spectrum into seven band and issues a DC level change for each band with the amplitude of the audio signal in that band  My board skips the lowest band and groups two together for the remainder to have three outputs to FET transitors  The FETs are PWM driven with the amplitude changes so an LED can be varied in brightness on each channel

#define MSGEQ7_STROBE_PIN 7 #define MSGEQ7_RESET_PIN 8 #define MSGEQ7_ANALOG_PIN A0 #define RED_LED 9 #define GREEN_LED 10 #define BLUE_LED 11 #define NUM_FREQUENCY_BANDS 7 // Global variables int volumeInBand[NUM_FREQUENCY_BANDS]; int minimumVolume, maximumVolume; void setup() { // Set the LED pins as outputs pinMode(RED_LED, OUTPUT); pinMode(GREEN_LED, OUTPUT); pinMode(BLUE_LED, OUTPUT); // Set up the MSGEQ7 IC pinMode(MSGEQ7_ANALOG_PIN, INPUT); pinMode(MSGEQ7_STROBE_PIN, OUTPUT); pinMode(MSGEQ7_RESET_PIN, OUTPUT); digitalWrite(MSGEQ7_RESET_PIN, LOW); digitalWrite(MSGEQ7_STROBE_PIN, HIGH); // Initialize the minimum and maximum volume levels minimumVolume = 1023; maximumVolume = 0; }

// This loop executes around 100 times per second void loop() { static unsigned long nextLoopTime = 50; int cutoffVolume; // Toggle the RESET pin of the MSGEQ7 to start reading from the lowest frequency band digitalWrite(MSGEQ7_RESET_PIN, HIGH); digitalWrite(MSGEQ7_RESET_PIN, LOW); // Read the volume in every frequency band from the MSGEQ7 for (int i=0; i<NUM_FREQUENCY_BANDS; i++) { digitalWrite(MSGEQ7_STROBE_PIN, LOW); delayMicroseconds(30); // Allow the output to settle volumeInBand[i] = analogRead(MSGEQ7_ANALOG_PIN); autoAdjustMinMax(volumeInBand[i]); digitalWrite(MSGEQ7_STROBE_PIN, HIGH); }

// A volume greater than 35% should turn the LED on cutoffVolume = map(35, 0, 100, minimumVolume, maximumVolume); // Turn the RED LED on if the volume in the lower frequency bands is high enough if (volumeInBand[0] > cutoffVolume || volumeInBand[1] > cutoffVolume) analogWrite(RED_LED, map(max(volumeInBand[0], volumeInBand[1]), cutoffVolume, maximumVolume, 0, 255)); else analogWrite(RED_LED, 0); // Turn the GREEN LED on if the volume in the middle frequency bands is high enough if (volumeInBand[2] > cutoffVolume || volumeInBand[3] > cutoffVolume) analogWrite(GREEN_LED, map(max(volumeInBand[2], volumeInBand[3]), cutoffVolume, maximumVolume, 0, 255)); else analogWrite(GREEN_LED, 0); // Turn the BLUE LED on if the volume in the lower frequency bands is high enough if (volumeInBand[4] > cutoffVolume || volumeInBand[5] > cutoffVolume) analogWrite(BLUE_LED, map(max(volumeInBand[4], volumeInBand[5]), cutoffVolume, maximumVolume, 0, 255)); else analogWrite(BLUE_LED, 0); // Execute this loop 20 times per second (every 50ms) if (millis() < nextLoopTime) delay(nextLoopTime - millis()); nextLoopTime += 50; }

// Automatically adjust the high and low volume. This routine is called 20 times per // second for each band, or 20 * 7 bands = 140 times per second. void autoAdjustMinMax(int volume) { static int increaseMin = 0; static int decreaseMax = 0; // Adjust the minimum volume level if (volume < minimumVolume) minimumVolume = volume; else { // Move the minimum volume level upwards (1 per second) if (++increaseMin > 140) { increaseMin = 0; minimumVolume++; } // Adjust the maximum volume level if (volume > maximumVolume) maximumVolume = volume; else { // Move the maximum volume level downwards (5 per second) if (++decreaseMax > 28) { decreaseMax = 0; // Keep a reasonable level of separation between max and min if (maximumVolume - minimumVolume > 100) maximumVolume--; }