Code for sketches included in the book – see the referenced figure numbers. This code can be copied and pasted into the Arduino IDE. 

Chapter 3.

Figure 3.2
/*
  Blink
  Turns an LED on for one second, then off for one second, repeatedly.
  Most Arduinos have an on-board LED you can control. On the UNO, MEGA and ZERO
  it is attached to digital pin 13, on MKR1000 on pin 6. LED_BUILTIN is set to
  the correct LED pin independent of which board is used.
  If you want to know what pin the on-board LED is connected to on your Arduino
  model, check the Technical Specs of your board at:
  https://www.arduino.cc/en/Main/Products

  modified 8 May 2014 by Scott Fitzgerald
  modified 2 Sep 2016 by Arturo Guadalupi
  modified 8 Sep 2016 by Colby Newman

  This example code is in the public domain.

  http://www.arduino.cc/en/Tutorial/Blink
*/

// the setup function runs once when you press reset or power the board
void setup() {
  // initialize digital pin LED_BUILTIN as an output.
  pinMode(LED_BUILTIN, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, HIGH);   // turn the LED on (HIGH is the voltage level)
  delay(1000);                       // wait for a second
  digitalWrite(LED_BUILTIN, LOW);    // turn the LED off by making the voltage LOW
  delay(1000);                       // wait for a second
}

Chapter 4.

Figure 4.6
// Blink2LEDs.ino, D. Brooks, July 2016
// alternates on/off between 2 LEDS
const int greenPin=7,redPin=8,delayTime=2000;
void setup() {
  Serial.begin(9600);
  pinMode(greenPin,OUTPUT); pinMode(redPin,OUTPUT);
  // Start with both LEDs on, just an arbitrary choice.
  digitalWrite(greenPin,HIGH); digitalWrite(redPin,HIGH);
  delay(delayTime);
}
void loop() {
  digitalWrite(greenPin,LOW); digitalWrite(redPin,HIGH);
  Serial.println("Red LED on.");
  delay(delayTime);
  digitalWrite(greenPin,HIGH); digitalWrite(redPin,LOW);
  Serial.println("Green LED on.");
  delay(delayTime);
}

Chapter 5.

Figure 5.6 
/* TMP_basic.ino, D. Brooks, October 2015
  Assumes TMP36 or compatible analog temperature sensor.
*/
const int TMPpin=A0;
int V_digitized, delayTime=5000; // 5 sec delay between readings
float V_analog,T; // temperature in deg C
void setup() {
  pinMode(TMPpin,INPUT); // optional pin mode setting (default)
  Serial.begin(9600);
}
void loop() {
  V_digitized=analogRead(TMPpin); // integer between 0 and 1023
  // NOTE: 5*V_digitized/1023; will give a value of 0! 5.0 or 5. forces
  // floating point arithmetic rather than integer arithmetic!
  V_analog=5.*V_digitized/1023;  // convert back to analog value
  //T=100*(V_analog - 0.5);         // convert analog value to T, deg C
   T=100*V_analog; // if using TMP35 (or LM35) sensor instead of TMP36
  Serial.print(V_digitized); Serial.print(", "); 
  Serial.println(T,1); // displays temperature to nearest 0.1 deg C
  delay(delayTime);
}

Chapter 6.

Figure 6.3
/* CdS.ino, D. Brooks, December 2016
  Using a CdS resistor in series with 10K resistor.
*/
const int CdS_pin = A0;
int V;
float V_CdS;
void setup ()
{
  Serial.begin(9600);
  pinMode (CdS_pin, INPUT);
}
void loop ()
{
  V = analogRead(CdS_pin); // digitized voltage across 10K resistor
  V_CdS = 5.*V/1023.; // analog voltage across 10K resistor
  Serial.print(V); 
  Serial.print(' '); 
  Serial.print(V_CdS);
  Serial.println();
  delay(200);
}

Chapter 7.

Figure 7.3
/* TMP36_with_LEDs.ino, D. Brooks, December, 2018
  Read air temperature using a TMP36 or TMP35 sensor.
  Control LEDs based on temperature
*/
const int greenPin=7,redPin=8;
const int TMP36pin=A0;    // connect center pin of TMP36 to A0
int V_digitized;    // digitized input voltage, integer from 0-1023
float V;            // V_digitized converted to a voltage
float T;            // the voltage converted to temperature
const float T_set=25.0;  // temperature at which red/green LEDs switched on/off
const int delayTime=1000; // delay time in milliseconds
void setup() {
  pinMode(TMP36pin,INPUT); // specify pin status
  pinMode(redPin,OUTPUT); pinMode(greenPin,OUTPUT)
  // initially both LEDs off...
  digitalWrite(redPin,LOW); digitalWrite(greenPin,LOW); 
  Serial.begin(9600);      // activate serial port
}
void loop() {
  V_digitized=analogRead(TMP36pin); // read the voltage
  Serial.print(V_digitized);
  V=5.0*V_digitized/1023;
  T=100*(V - 0.5);
  // T=100*V if using TMP35 (or LM35) sensor instead of TMP36
  Serial.print("Temperature (deg C) = "); Serial.println(T,1);
  if (T>=T_set) {
    digitalWrite(redPin,HIGH); digitalWrite(greenPin,LOW);
  }
  else {
    digitalWrite(redPin,LOW); digitalWrite(greenPin,HIGH);    
  }
  delay(delayTime);
}

Chapter 8.

Figure 8.2
/* LCD1602_TMP36, D. Brooks, December 2018
  Display temperature from TMP36 or similar.
*/
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>
// set the LCD address to 0x27 for a 16 chars 2 line display
LiquidCrystal_I2C lcd(0x27,16,2); 
char line1[]="Air Temp. (C)";
const int TMP36pin=A0;
int V_digitized, delayTime=5000;
float V,T;
void setup() {
  //Serial.begin(9600);
  pinMode(TMP36pin,INPUT);
  lcd.init(); //initialize the lcd
  lcd.backlight(); //turn on the backlight  
}
void loop() {
  lcd.clear();
  lcd.setCursor(0,0);
  lcd.print(line1);  
  V_digitized=analogRead(TMP36pin); 
  Serial.print(V_digitized);
  V=5.0*V_digitized/1023;
  //T=100*(V - 0.5);
  T=100*V; // if using TMP35 (or LM35) sensor instead of TMP36  
  lcd.setCursor(0,1);
  lcd.print(T,1);  
  delay(delayTime);
  }

Chapter 9.

Figure 9.2
  /* BME280_Adafruit.ino, D. Brooks, January 2019 
    Logs data from Adafruit's BME280 T/RH/P breakout board, 
    using the I2C interface and Adafruit data logging shield. 
  */ 
  #include  <Wire.h>
  #include  <RTClib.h>
  #include  <SD.h>
  #include  <Adafruit_Sensor.h>
  #include  <Adafruit_BME280.h>
 Adafruit_BME280 bme; // I2C 
 // Setup data logging 
 RTC_DS1307 rtc; // real time clock module, old datalogger shield 
 //RTC_PCF8523 rtc;   // new datalogger shield 
 const int SDpin=10; 
 const long int DelayTime=120000L; 
 File logfile; 
 char filename[]="BME280.CSV"; 
 int year,month,day,hour,minute,second; 
 float T,P,RH,P_sealevel; 
 const int delayTime=5000; 
 void setup() { 
   Serial.begin(9600); 
   // setup sensors and data logging, assuming everything will work 
   bme.begin(); SD.begin(SDpin); logfile=SD.open(filename,FILE_WRITE); 
   Serial.println("Ready to go!");   
   Serial.println("YY/MM/DD,HH:MM:SS,day_frac,T(C),P(mbar),P_sealevel(inHg),RH(%)");   
   logfile.println("YY/MM/DD,HH:MM:SS,day_frac,T(C),P(mbar),P_sealevel(inHg),RH(%)"); 
   logfile.flush(); 
 } 
 void loop() { 
   DateTime now=rtc.now(); 
   year=now.year(); month=now.month(); day=now.day(); 
   hour=now.hour(); minute=now.minute(); second=now.second(); 
   Serial.print(year); Serial.print('/'); Serial.print(month); Serial.print('/'); 
   Serial.print(day); Serial.print(','); Serial.print(hour);Serial.print(':'); 
   Serial.print(minute); Serial.print(':'); Serial.print(second);  Serial.print(','); 
   logfile.print(year); logfile.print('/'); logfile.print(month); logfile.print('/'); 
   logfile.print(day); logfile.print(','); logfile.print(hour); logfile.print(':'); 
   logfile.print(minute); logfile.print(':'); logfile.print(second);  logfile.print(',');  
   // Write day expressed as decimal fraction. 
   Serial.print(day+hour/24.+minute/1440.+second/86400.,6); Serial.print(','); 
   logfile.print(day+hour/24.+minute/1440.+second/86400.,6); logfile.print(','); 
   // Read sensor data. 
  T=bme.readTemperature(); delay(10); // just to make sure read is done... 
  P=bme.readPressure(); delay(10); RH=bme.readHumidity(); delay(10); 
  // Write to serial port and SD card file. 
  Serial.print(T,1);  Serial.print(',');    
  Serial.print(P/100.0,1); Serial.print(','); 49   // for a site elevation of 131 m... 
  P_sealevel=seaLevel(P/100.,0.131); 
  Serial.print(P_sealevel,2); Serial.print(',');
  Serial.print(RH,1); Serial.println(); logfile.print(T,1);  logfile.print(','); 
  logfile.print(P/100.0,1); logfile.print(','); 
  logfile.print(P_sealevel,2); logfile.print(','); 
  logfile.print(RH,1); logfile.println(); logfile.flush(); 
  delay(delayTime); 
} 
float seaLevel(float P,float elev) { 
  // conversion from station pressure in mbar to sea level "Hg, elevation in km. 
  return 29.921/1013.25*P/exp(-0.119*elev-0.0013*elev*elev); 
}

Chapter 10.

Figure 10.2
/* DataLogTemplate.ino, D. Brooks, May 2018
  Template code for using microSD and DS1307 board for
  data logging with date/time stamp.
  NOTE: new Adafruit datalogging shield uses PCF8523 RTC module
  rather than DS1307 on old shields.
*/
#include <Wire.h> // if you will attach an I2C sensor
#include <SD.h>
#include <RTClib.h>
// RTC_DS1307 rtc; // real time clock module, old datalogger shield
RTC_PCF8523 rtc;   // new datalogger shield
const int SDpin=10,DelayTime=5000;
File logfile;
char filename[]="LOG_TEST.CSV";
int year,month,day,hour,minute,second;
void setup(void) 
{
  Serial.begin(9600); rtc.begin(); 
  Wire.begin(); 
  //RTC.adjust(DateTime(__DATE__,__TIME__)); // needed only for new RTC not yet set.
  if (!SD.begin(SDpin)) {Serial.println("Card failed."); 
    delay(50);exit(0);
  }
  Serial.println("card initialized.");
  logfile = SD.open(filename, FILE_WRITE); 
  if (!logfile) {
    Serial.println("Couldn't create file."); delay(50); exit(0);
  }  
  Serial.print("Logging to file "); Serial.println(filename);      
  // Optionally, write header line here, with logfile.flush() uncommented.
  // logfile.flush();      
}
void loop(void) 
{
  // Get date and time.
  DateTime now=rtc.now();
  year=now.year(); month=now.month(); day=now.day();
  hour=now.hour(); minute=now.minute(); second=now.second();
  logfile.print(year); logfile.print('/'); logfile.print(month); logfile.print('/');
  logfile.print(day); logfile.print(','); logfile.print(hour); logfile.print(':');
  logfile.print(minute); logfile.print(':'); logfile.print(second);  logfile.print(','); 
  // Write day expressed as decimal fraction.
  logfile.print(day+hour/24.+minute/1440.+second/86400.,6);
  // Write other data here...
  logfile.println(); logfile.flush(); delay(DelayTime);
}

Figure 10.3
/* RCT_2.ino, D. Brooks, August 2018
  This code has been modified to work with both old and new
  datalogging shields. The clock chip on the shields is
  different.
*/
 #include <Wire.h>
#include "RTClib.h"
RTC_DS1307 RTC; // old data logger shield
//RTC_PCF8523 RTC;  // new data logger shield
void setup() {
  Serial.begin(9600);
  Wire.begin();
  if (!RTC.begin()) {
    Serial.println("RTC not running.");
    exit;
  }
  RTC.adjust(DateTime(__DATE__,__TIME__));
  DateTime now=RTC.now();
  Serial.print(now.year());
  Serial.print('/');
  Serial.print(now.month());
  Serial.print('/');
  Serial.print(now.day());
  Serial.print(' ');
  Serial.print(now.hour());
  Serial.print(':');
  Serial.print(now.minute());
  Serial.print(':');
  Serial.println(now.second());
}
void loop() {
}

Figure 10.4
/* BME280_Adafruit.ino, D. Brooks, January 2019
  Logs data from Adafruit's BME280 T/RH/P breakout board,
  using the I2C interface and Adafruit data logging shield.
*/
#include <Wire.h>
#include <RTClib.h>
#include <SD.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>
Adafruit_BME280 bme; // I2C
// Setup data logging
RTC_DS1307 rtc; // real time clock module, old datalogger shield
//RTC_PCF8523 rtc;   // new datalogger shield
const int SDpin=10;
const long int DelayTime=120000L;
File logfile;
char filename[]="BME280.CSV";
int year,month,day,hour,minute,second;
float T,P,RH,P_sealevel;
const int delayTime=5000;
void setup() {
  Serial.begin(9600);
  // setup sensors and data logging, assuming everything will work
  bme.begin(); SD.begin(SDpin); logfile=SD.open(filename,FILE_WRITE);
  Serial.println("Ready to go!");  
  Serial.println("YY/MM/DD,HH:MM:SS,day_frac,T(C),P(mbar),P_sealevel(inHg),RH(%)");  
  logfile.println("YY/MM/DD,HH:MM:SS,day_frac,T(C),P(mbar),P_sealevel(inHg),RH(%)");
  logfile.flush();
}
void loop() {
  DateTime now=rtc.now();
  year=now.year(); month=now.month(); day=now.day();
  hour=now.hour(); minute=now.minute(); second=now.second();
  Serial.print(year); Serial.print('/'); Serial.print(month); Serial.print('/');
  Serial.print(day); Serial.print(','); Serial.print(hour);Serial.print(':');
  Serial.print(minute); Serial.print(':'); Serial.print(second);  Serial.print(',');
  logfile.print(year); logfile.print('/'); logfile.print(month); logfile.print('/');
  logfile.print(day); logfile.print(','); logfile.print(hour); logfile.print(':');
  logfile.print(minute); logfile.print(':'); logfile.print(second);  logfile.print(','); 
  // Write day expressed as decimal fraction.
  Serial.print(day+hour/24.+minute/1440.+second/86400.,6); Serial.print(',');
  logfile.print(day+hour/24.+minute/1440.+second/86400.,6); logfile.print(',');
  // Read sensor data.
  T=bme.readTemperature(); delay(10); // just to make sure read is done...
  P=bme.readPressure(); delay(10); RH=bme.readHumidity(); delay(10);
  // Write to serial port and SD card file.
  Serial.print(T,1);  Serial.print(',');   
  Serial.print(P/100.0,1); Serial.print(',');
  // for a site elevation of 131 m...
  P_sealevel=seaLevel(P/100.,0.131);
  Serial.print(P_sealevel,2); Serial.print(',');
  Serial.print(RH,1); Serial.println(); logfile.print(T,1);  logfile.print(',');   
  logfile.print(P/100.0,1); logfile.print(',');
  logfile.print(P_sealevel,2); logfile.print(',');
  logfile.print(RH,1); logfile.println(); logfile.flush();
  delay(delayTime);
}
float seaLevel(float P,float elev) {
  // conversion from station pressure in mbar to sea level "Hg, elevation in km.
  return 29.921/1013.25*P/exp(-0.119*elev-0.0013*elev*elev);
}

Chapter 11.

Figure 11.3
/* DHT22_LCD.ino, D. Brooks, December 2018
  Display air temperature and RH on LCD, using a DHT22 sensor.
  (Serial port output is optional.)
*/
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
LiquidCrystal_I2C lcd(0x27,16,2); // for a 16x2 LCD 
#include <DHT.h>
#define DHTPIN 8
#define DHTTYPE DHT22    // specify DHT11 or DHT22
DHT dht(DHTPIN,DHTTYPE); // create "instance" of the DHT object
float DHT_T,DHT_TF,DHT_RH,DHT_HIC, DewPt; // DHT values
const int delayTime=2000;  // delay time between readings
void setup() {
  pinMode(DHTPIN,INPUT); 
  dht.begin(); Serial.begin(9600); 
  lcd.init(); lcd.backlight(); lcd.clear();
  lcd.setCursor(0,0); lcd.print("Initializing...");
}
void loop() {
  DHT_T=dht.readTemperature(); DHT_RH=dht.readHumidity(); 
  DHT_TF=dht.readTemperature(true); // get temperature in deg F
  DHT_HIC = dht.computeHeatIndex(DHT_T, DHT_RH, false);
  // optional output to serial port window
  Serial.print("DHT22 temperature C and F, heat index, relative humidity, dewpoint ");
  Serial.print(DHT_T,1); Serial.print(", ");
  Serial.print(DHT_TF,1); Serial.print(", "); 
  Serial.print(DHT_RH,0); Serial.print(", ");
  Serial.print("DHT_HIC,1"); Serial.print(", ");
  DewPt=dewpoint(DHT_T,DHT_RH);
  Serial.println(DewPt,1);
  // LCD output
  lcd.clear(); lcd.setCursor(0,0); // (column,row) row=0 is top row
  lcd.print("T C & F, RH %"); 
  lcd.setCursor(0,1);  
  lcd.print(DHT_T,1); lcd.print(", "); lcd.print(DHT_TF,1);
  lcd.print(", "); lcd.print(DHT_RH,0);
  delay(delayTime);
}
float dewpoint(float T,float RH) {
// See, for example, http://www.paroscientific.com/dewpoint.htm
// input: T in deg C and RH 0-100 %
  float a=17.27,b=237.7, alpha=a*T/(b+T)+log(RH/100.); 
  return b*alpha/(a-alpha);
}

Chapter 12.

Figure 12.4
/* RGB_test, D. Brooks, December 2018
  produces blended colors by turning on/off
  all possible combinations of the three chips
  on a common-anode RGB LED.
*/
// blue LED not used in this code.
int Red=9,Grn=10,Blu=11;
void setup() {
  Serial.begin(9600);
  pinMode(Blu,OUTPUT);pinMode(Grn,OUTPUT);pinMode(Red,OUTPUT);
  // 255 is "OFF" for common anode LEDs
  analogWrite(Blu,255);analogWrite(Grn,255);analogWrite(Red,255);
}
void loop() {
  analogWrite(Red,0); analogWrite(Grn,255); analogWrite(Blu,255); delay(1000);
  analogWrite(Red,255); analogWrite(Grn,0); analogWrite(Blu,255); delay(1000);
  analogWrite(Red,255); analogWrite(Grn,255); analogWrite(Blu,0); delay(1000);
  analogWrite(Red,0); analogWrite(Grn,255); analogWrite(Blu,0); delay(1000);
  analogWrite(Red,0); analogWrite(Grn,0); analogWrite(Blu,255); delay(1000);
  analogWrite(Red,255); analogWrite(Grn,0); analogWrite(Blu,0); delay(1000);
  analogWrite(Red,0); analogWrite(Grn,0); analogWrite(Blu,0); delay(1000);
}

Figure 12.5
/* RGB_cycle.ino, D. Brooks, December 2018
  Use PWM to cycle RGB LED through the color spectrum.
  See stackoverflow referenced in line 27.
*/
const int redPin=9,greenPin=10,bluePin=11;
int dt=100;
float lambda;
float R,G,B;
void setup() {
  Serial.begin(9600);
}
void loop() {
  delay(250);
  for (lambda=400; lambda<=700; lambda+=5) {
    //makeColor(lambda);
    spectral_color(lambda);
    analogWrite(redPin,255-round(255.*R));
    analogWrite(greenPin,255-round(255.*G));
    analogWrite(bluePin,255-round(255.*B));
    Serial.print(lambda);Serial.print(',');
    Serial.print(round(255.*R));Serial.print(',');
    Serial.print(round(255.*G));Serial.print(',');
    Serial.print(round(255.*B));Serial.println();    
    delay(dt);
  }
}
void spectral_color(int lambda) {
  // see http://stackoverflow.com/questions/3407942/rgb-values-of-visible-spectrum      
  float t;
  R=0.; G=0.; B=0.;
  if ((lambda>=400)&&(lambda<410))      { t=(lambda-400.0)/(410.0-400.0);  R=    +(0.33*t)-(0.20*t*t); }
  else if ((lambda>=410)&&(lambda<475)) { t=(lambda-410.0)/(475.0-410.0);  R=0.14         -(0.13*t*t); }
  else if ((lambda>=545)&&(lambda<595))  { t=(lambda-545.0)/(595.0-545.0); R=    +(1.98*t)-(     t*t); }
  else if ((lambda>=595)&&(lambda<650)) { t=(lambda-595.0)/(650.0-595.0);  R=0.98+(0.06*t)-(0.40*t*t); }
  else if ((lambda>=650)&&(lambda<700)) { t=(lambda-650.0)/(700.0-650.0);  R=0.65-(0.84*t)+(0.20*t*t); }
  else R=0;
  if ((lambda>=415)&&(lambda<475))      { t=(lambda-415.0)/(475.0-415.0);  G=             +(0.80*t*t); }
  else if ((lambda>=475)&&(lambda<590))  { t=(lambda-475.0)/(590.0-475.0); G=0.8 +(0.76*t)-(0.80*t*t); }
  else if ((lambda>=585)&&(lambda<639)) { t=(lambda-585.0)/(639.0-585.0);  G=0.84-(0.84*t)           ; }
  else G=0.;
  if ((lambda>=400)&&(lambda<475))      { t=(lambda-400.0)/(475.0-400.0);  B=    +(2.20*t)-(1.50*t*t); }
  else if ((lambda>=475)&&(lambda<560)) { t=(lambda-475.0)/(560.0-475.0);  B=0.7 -(     t)+(0.30*t*t); }
  else B=0.;
}

Chapter 13.

Figure 13.2
/* SoilMoisture_LED.ino, D. Brooks, December 2018
  Read and display soil moisture from dfrobot capacitive probe. Use
  values to turn red or green LED on/off.
*/
const int redPin=5,greenPin=4;
const int SoilPin=A0; 
int V;   // digitized input voltage, integer from 0-1023
const int V_set=500; // digitized voltage at which red/green LEDs switch on/off
const int delayTime=1000;// delay time in milliseconds
void setup() {
  pinMode(SoilPin,INPUT); // specify pin status
  pinMode(redPin,OUTPUT); pinMode(greenPin,OUTPUT);
  // initially both LEDs off...
  digitalWrite(redPin,LOW); digitalWrite(greenPin,LOW); 
  Serial.begin(9600);    // activate serial port
}
void loop() {
  V=analogRead(SoilPin); // read the voltage
  Serial.print("Probe voltage: "); Serial.println(V);
  if (V>=V_set) {
    digitalWrite(redPin,HIGH); digitalWrite(greenPin,LOW);
  }
  else {
    digitalWrite(redPin,LOW); digitalWrite(greenPin,HIGH);    
  }
  delay(delayTime);
}

Chapter 14.

Figure 14.3
/* relayController.ino, D. Brooks, March 2017
  Test a solid-state relay.
  Use digital pin 8 to control the relay. 
*/
const int relay=8;
void setup() {
  Serial.begin(9600);
  pinMode(relay,OUTPUT);
  digitalWrite(relay,HIGH); // start with LED off
}
void loop() {
  digitalWrite(relay,HIGH);
  Serial.println("Turn relay off.");
  delay(3000);
  digitalWrite(relay,LOW);
  Serial.println("Turn relay on.");
  delay(3000);
}

Chapter 15.

Figure 15.3
/* plantower_DHT22_log_2, D. Brooks, September 2018
  Logs data from a Plantower PMS5003 sensor and a DHT22 T/RH sensor.
  A data stream is received about once per second and KNT_MAX values
  are averaged (200 samples = about 3 minutes). See also example code from Adafruit.
  Includes particle counts and conversion to PM2.5 AQI values.
*/
#define ECHO_TO_SERIAL 1
#define KNT_MAX 200
#include <SoftwareSerial.h>
SoftwareSerial pmsSerial(2, 3);
#include <DHT.h>
#define DHTPIN 8
#define DHTTYPE DHT22
DHT dht(DHTPIN,DHTTYPE);
#include <SD.h>
#define SDpin 10
#include <SPI.h>
#include <RTClib.h>
RTC_DS1307 rtc;
int knt=0;
int yr,mon,dy,hr,mn,sec;
float pm1=0,pm25=0,pm10=0,AQI25,AQI10;
float p03=0,p05=0,p10=0,p25=0,p50=0,p100=0;
File logfile;
void setup() { 
  rtc.begin(); Serial.begin(9600);
  pmsSerial.begin(9600);
  Serial.print(F("Initializing SD card..."));
  pinMode(SDpin,OUTPUT);
  if (!SD.begin(SDpin)) {Serial.println("Card failed."); 
  delay(50);exit(0);}
  Serial.println("card initialized.");  
  logfile=SD.open("PM25_DHT.CSV",FILE_WRITE);
  logfile.println("yr,mon,day,hr,min,sec,day_frac,DHT_T,DHT_RH,PM1,PM2.5,PM10,AQI2.5,AQI10,p0.3,p0.5,p1.0,p2.5,p5,p10");
  logfile.flush();
}
struct pms5003data {
uint16_t framelen;
uint16_t pm10_standard, pm25_standard, pm100_standard;
uint16_t pm10_env, pm25_env, pm100_env;
uint16_t particles_03um, particles_05um, particles_10um, particles_25um, particles_50um, particles_100um;
uint16_t unused;
uint16_t checksum;
};
struct pms5003data data;
void loop() {
  if (readPMSdata(&pmsSerial)) { // reading data was successful!
    pm1+=data.pm10_env; pm25+=data.pm25_env; pm10+=data.pm100_env;
    p03+=data.particles_03um; p05+=data.particles_05um; 
    p10+=data.particles_10um; p25+=data.particles_25um;
    p50+=data.particles_50um; p100+=data.particles_100um;
    knt++;
    if (knt==KNT_MAX) {
      DateTime now=rtc.now();
      yr=now.year(); mon=now.month(); dy=now.day();
      hr=now.hour(); mn=now.minute(); sec=now.second();   
      pm1/=knt; pm25/=knt; pm10/=knt; 
      p03/=knt; p05/=knt; p10/=knt; 
      p25/=knt; p50/=knt; p100/=knt;
      // Convert to AQI value.
      if (pm25<=12.0) {
        AQI25=(50.-0.)/(12.0-0.)*(pm25-0.0)+0.;
      }
      else if (pm25<=35.4) {
        AQI25=(100.-50.)/(35.4-12.0)*(pm25-12.0)+50.;
      }
      else if (pm25<=55.4) {
        AQI25=(150.-100.)/(55.4-35.4)*(pm25-35.4)+100.;
      }
      else if (pm25<=150.4) {
        AQI25=(200.-150.)/(150.4-55.4)*(pm25-55.4)+150.;
      }
      else if (pm25<=250.4) {
        AQI25=(300.-200.)/(250.4-150.4)*(pm25-150.4)+200.;
      }
      else if (pm25<=350.4) {
        AQI25=(400.-300.)/(350.4-250.4)*(pm25-250.4)+300.;
      }
      else if  (pm25<=500.4) { 
        AQI25=(500.-400.)/(500.4-350.4)*(pm25-350.4) +400.;
      }
      else AQI25=501.;
      if (pm10<=54.) {
        AQI10=(50.-0.)/(54.-0.)*(pm10-0.)+0.;
      }
      else if (pm10<=154.) {
        AQI10=(100.-50.)/(154.-54.)*(pm10-54.)+50.;
      }
      else if (pm10<=254.) {
        AQI10=(150.-100.)/(254.-154.)*(pm10-154.)+100.;
      }
      else if (pm10<=354.) {
        AQI10=(200.-150.)/(354.-254.)*(pm10-254.)+150.;
      }
      else if (pm10<=424.) {
        AQI10=(300.-200.)/(424.-354.)*(pm10-354.)+200.;
      }
      else if (pm10<=504) {
        AQI10=(400-300)/(504.-424.)*(pm10-424.);
      }
      else if (pm10<=604.) {
        AQI10=(500.-400.)/(604.-504.)*(pm10-504.)*400.;
      }
      else AQI10=501.;
      logfile.print(yr);     logfile.print(','); logfile.print(mon);    logfile.print(',');
      logfile.print(dy);     logfile.print(','); logfile.print(hr);     logfile.print(',');
      logfile.print(mn); logfile.print(','); logfile.print(sec);    logfile.print(',');
      logfile.print(dy+hr/24.+mn/1440.+sec/86400.,5); logfile.print(',');
      logfile.print(dht.readTemperature(),1); logfile.print(',');
      logfile.print(dht.readHumidity(),0);    logfile.print(',');     
      logfile.print(pm1,1);   logfile.print(','); logfile.print(pm25,1);  logfile.print(',');
      logfile.print(pm10,1);  logfile.print(','); logfile.print(AQI25,0); logfile.print(',');
      logfile.print(AQI10,0); logfile.print(','); logfile.print(p03); logfile.print(',');
      logfile.print(p05); logfile.print(','); logfile.print(p10); logfile.print(',');
      logfile.print(p25); logfile.print(','); logfile.print(p50); logfile.print(',');
      logfile.println(p100); logfile.flush(); 
      #if ECHO_TO_SERIAL
        Serial.print(dy);Serial.print(' ');Serial.print(hr);Serial.print(':');Serial.print(mn);
        Serial.print(':');Serial.print(sec);Serial.print(' ');
        Serial.print(pm1,1);Serial.print(", ");Serial.print(pm25,1);Serial.print(", ");
        Serial.print(pm10,1);Serial.println();
      #endif // ECHO_TO_SERIAL
      pm1=0; pm25=0; pm10=0; // reset PM totals
      p03=0; p05=0; p10=0; p25=0; p50=0; p100=0; knt=0;
    } 
  }
}
boolean readPMSdata(Stream *s) {
if (! s->available()) { return false; }
// Read a byte at a time until we get to the special '0x42' start-byte
if (s->peek() != 0x42) { s->read(); return false; }
// Now read all 32 bytes
if (s->available() < 32) { return false; }
uint8_t buffer[32]; uint16_t sum = 0; s->readBytes(buffer, 32);
// get checksum ready
for (uint8_t i=0; i<30; i++) { sum += buffer[i]; }
// The data comes in endian'd, this solves it so it works on all platforms
uint16_t buffer_u16[15];
for (uint8_t i=0; i<15; i++) {
buffer_u16[i] = buffer[2 + i*2 + 1]; buffer_u16[i] += (buffer[2 + i*2] << 8); }
// put it into a nice struct :)
memcpy((void *)&data, (void *)buffer_u16, 30);
if (sum != data.checksum) { Serial.println("Checksum failure"); return false; }
return true; // success!
}

Chapter 16.

Figure 16.3
/*************************************************** 
  This is a library example for the MLX90614 Temp Sensor
  Designed specifically to work with the MLX90614 sensors in the
  adafruit shop
  ----> https://www.adafruit.com/products/1748
  ----> https://www.adafruit.com/products/1749
  These sensors use I2C to communicate, 2 pins are required to  
  interface
  Adafruit invests time and resources providing this open source code, 
  please support Adafruit and open-source hardware by purchasing 
  products from Adafruit!
  Written by Limor Fried/Ladyada for Adafruit Industries.  
  BSD license, all text above must be included in any redistribution
 ****************************************************/
#include <Wire.h>
#include <Adafruit_MLX90614.h>
Adafruit_MLX90614 mlx = Adafruit_MLX90614();
void setup() {
  Serial.begin(9600);
  Serial.println("Adafruit MLX90614 test");  
  mlx.begin();  
}
void loop() {
  Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempC()); 
  Serial.print("*C\tObject = "); Serial.print(mlx.readObjectTempC()); Serial.println("*C");
  Serial.print("Ambient = "); Serial.print(mlx.readAmbientTempF()); 
  Serial.print("*F\tObject = "); Serial.print(mlx.readObjectTempF()); Serial.println("*F");
  Serial.println();
  delay(1000);
}

Chapter 17.

Figure 17.3
/* ADS1115_TMP36, D. Brooks, January 2019
  Shows how to read 1 channel from ADS1115 breakout.
*/
#include <Wire.h>
#include <Adafruit_ADS1015.h> // This library works for both 1015 and 1115
Adafruit_ADS1115 ads(0x48); // default address is 0x48
float V0,V1,V2,V3,DtoA,T;
int16_t adc0,adc1,adc2,adc3;  // ADC reading produces 16-bit integer
const int delayTime=5000;
void setup(void) 
{
  Serial.begin(9600); 
  Wire.begin(); ads.begin();
  //ads.setGain(GAIN_ONE);             DtoA=0.125/1000;    // 4.096 V
  ads.setGain(GAIN_TWO);       DtoA=0.0625/1000;   // 2.048 V
  //ads1115.setGain(GAIN_TWOTHIRDS); DtoA=0.187506/1000; // 6.144 V (default gain)     
  //ads1115.setGain(GAIN_FOUR);      DtoA=0.03125/1000;  // 1.024 V
  //ads1115.setGain(GAIN_EIGHT);     DtoA=0.015625/1000; // 0.512 V
  //ads1115.setGain(GAIN_SIXTEEN);   DtoA=0.007813/1000; // 0.256 V
}
void loop(void) 
{
  adc0 = ads.readADC_SingleEnded(0);
  //adc1 = ads.readADC_SingleEnded(1);
  //adc2 = ads.readADC_SingleEnded(2);
  //adc3 = ads.readADC_SingleEnded(3);
  V0 = adc0 * DtoA;
  //V1 = adc1 * DtoA;
  //V2 = adc2 * DtoA;
  //V3 = adc3 * DtoA; 
  //T=(V0-0.5)*100.;
  T=V0*100.;
  Serial.print("Temperature, *C: "); Serial.println(T,2);
  delay(delayTime);
}

Chapter 18.

Figure 18.3
/* Vaisala_SHT1x_AM2315_log.ino, [C] D. Brooks, October 2018
  Compares analog-output Vaisala HMP260 with three other T/RH sensors:
    DHT22, Adafruit ID 385, $10 (10K pull-up resistor included, see www.adafruit.com)
    AM2315, Adafruit ID 1293, $30 (needs 2 10K pull-up resistors, not included)
    SHT10, Adafruit ID 1298, $40 (10K pull-up resistor included)
  Uses any Arduino UNO or compatible plus:
    Data logging shield, Adafruit ID 1141, $14 (required coin cell battery not included)
    ADS1115 16-bit ADC, programmable gain amplifier, Adafruit 1085, $15
  HMP60 outputs 0->2.5 VDC (one possible choice), Ch1=humidity, Ch2=temperature,
    calibration linear over 0-2.5 V, 0->100% for RH, -40->60C for T.
*/
#define ECHO_TO_FILE 1   // 0/1 = Write to file turned off/on
#define ECHO_TO_SERIAL 1 // 0/1 = Write to serial port turned off/on
// setup for AM2315
#include <Wire.h>
#include <Adafruit_AM2315.h>
Adafruit_AM2315 am2315;
float am2315_T,am2315_H;
// setup for SHT1x
#include <SHT1x.h>
#define dataPin 6
#define clockPin 7
float temp_c, humidity;
SHT1x sht1x(dataPin,clockPin);
// setup for DHT22 (optional extra sensor for comparison)
#include <DHT.h>
#define DHTPIN 8
#define DHTTYPE DHT22
DHT dht(DHTPIN,DHTTYPE);
float DHT_T,DHT_RH; // DHT22 output
// setup for SD card and clock
#include <SD.h>
#define SDpin 10
#include <RTClib.h>
RTC_DS1307 rtc; // old Adafruit datalogger shield clock
//RTC_PCF8523 rtc;  // new datalogger shield clock
#include <Adafruit_ADS1015.h> // same library for 1015 or 1115
Adafruit_ADS1115 ads(0x48); // default address is 0x48
float DtoA; // Convert ADS digital counts to analog voltage.
float T,RH,T_V,RH_V; // variables for HMP60 output
float dayFrac; // day, hour, minute, second converted to fractional day
const long delayTime=120000L; // delay time in milliseconds (2 m)
int16_t adc0,adc1;  // ADC reading produces 16-bit integer
int Y,D,MM,H,M,S;
File logfile;
char filename[]="VAISALA.CSV";
void setup() {
  am2315.begin();
  ads.begin();
  ads.setGain(GAIN_ONE); DtoA=0.125/1000; // 0-4.096 V
  Serial.begin(9600); pinMode(SDpin,OUTPUT);
  #if ECHO_TO_FILE 
    if (!SD.begin(SDpin)) {Serial.println("Card failed."); 
    delay(50);exit(0);}
    Serial.println("card initialized."); 
    Serial.print("Logging to: "); Serial.println(filename);   
    logfile=SD.open(filename,FILE_WRITE);
    logfile.print("yr,mon,day,hr,min,sec,day_frac,HMP60_T,HMP60_RH,DHT_T,DHT_RH,"); 
    logfile.println("nSHT1x_T,SHT1x_RH,AM2315_T,AM2315_RH"); 
    logfile.flush();
  #endif // ECHO_TO_FILE 
  rtc.begin();
  if (!rtc.isrunning()) {
    Serial.println("RTC not running."); exit;
  }  
  else Serial.println("RTC is running."); 
  // Uncomment this line with new logging shield or if date/time is off.
  // Of course, will work only when code uploaded and run from computer USB.
  //rtc.adjust(DateTime(__DATE__, __TIME__)); 
}
void loop() {
  DateTime now=rtc.now();  
  Y=now.year(); MM=now.month(); D=now.day();
  H=now.hour(); M=now.minute(); S=now.second();
  dayFrac=D+H/24.+M/1440.+S/86400;
  // read HMP60
  adc0 = ads.readADC_SingleEnded(0); adc1 = ads.readADC_SingleEnded(1);  
  RH_V=adc0*DtoA; T_V=adc1*DtoA; RH=100.*RH_V/2.5; T=100.*T_V/2.5-40.;
  // read DHT22
  DHT_T=dht.readTemperature(); DHT_RH=dht.readHumidity();
  // read SHT1x
  temp_c=sht1x.readTemperatureC();
  humidity=sht1x.readHumidity();
  // read AM2315
  am2315_T=am2315.readTemperature();
  am2315_H=am2315.readHumidity();
  #if ECHO_TO_SERIAL
    Serial.print(" V, Temperature (deg C) = "); 
      Serial.print(T_V,4); Serial.print(", "); Serial.println(T,2);
    Serial.print(" V, Relative humidity (%) = "); 
      Serial.print(RH_V,4); Serial.print(", "); Serial.println(RH,1);
    Serial.print("SHT1x T, RH = "); Serial.print(temp_c,2);
      Serial.print(", "); Serial.println(humidity,1);  
    Serial.println("----------------------");
  #endif // ECHO_TO_SERIAL
  #if ECHO_TO_FILE 
    logfile.print(Y);          logfile.print(',');
    logfile.print(MM);         logfile.print(',');
    logfile.print(D);          logfile.print(',');
    logfile.print(H);          logfile.print(',');
    logfile.print(M);          logfile.print(',');
    logfile.print(S);          logfile.print(',');  
    logfile.print(dayFrac,6);  logfile.print(',');
    logfile.print(T,2);        logfile.print(','); // Vaisala HMP60 data
    logfile.print(RH,1);       logfile.print(',');
    logfile.print(DHT_T,2);    logfile.print(','); // Adafruit DHT22 data
    logfile.print(DHT_RH,1);   logfile.print(',');
    logfile.print(temp_c,2);   logfile.print(','); // Adafruit SHT1x data
    logfile.print(humidity,1); logfile.print(',');
    logfile.print(am2315_T,2); logfile.print(','); // Adafruit AM2315 data
    logfile.print(am2315_H,1); logfile.println();
    logfile.flush(); // dump buffer onto SD card
  #endif // ECHO_TO_FILE
  delay(delayTime);
}

Chapter 19.

Figure 19.2
/* VEML7700_GA1A.ino, D. Brooks, April 2019
  Tests Adafruit VEML7700 and GA1A12S202 breakout boards, collecting
  data with Adafruit data logging shield at ~2 minute intervals.
*/
#include <Wire.h>
#include <RTClib.h>
//RTC_DS1307 rtc; // old data logging shield clock
RTC_PCF8523 rtc;  // new datalogger shield clock
#include <SD.h>
#include <Adafruit_VEML7700.h>
Adafruit_VEML7700 veml = Adafruit_VEML7700();
File logfile; char filename[]="VEML7700.CSV";
float VEML_lux,VEML_raw,VEML_white,lux_corrected,dayFrac,GA1A_V,GA1A_lux;
// raw should be long int
float range=5.05; // tested for the Arduino board I'm using.
float white_corrected;
int YR,MON,DAY,HR,MIN,SEC,GA1A_raw;
const long int delayTime=120000L;
const int SDpin=10, GA1Apin=A0;
void setup() {
  Serial.begin(9600);
  Serial.println(F("Adafruit VEML7700 Test"));
  if (!veml.begin()){
    Serial.println(F("Sensor not found"));
    while (1);
  }
  Serial.println(F("Sensor found"));
  veml.setGain(VEML7700_GAIN_1_8); // settings for bright light
  veml.setIntegrationTime(VEML7700_IT_25MS);
  Serial.print(F("Gain: ")); // optional serial port output
  switch (veml.getGain()) {
    case VEML7700_GAIN_1:   Serial.println("1");   break;
    case VEML7700_GAIN_2:   Serial.println("2");   break;
    case VEML7700_GAIN_1_4: Serial.println("1/4"); break;
    case VEML7700_GAIN_1_8: Serial.println("1/8"); break;
  }
  Serial.print(F("Integration Time (ms): "));
  switch (veml.getIntegrationTime()) { // optional serial port output
    case VEML7700_IT_25MS:  Serial.println("25");  break;
    case VEML7700_IT_50MS:  Serial.println("50");  break;
    case VEML7700_IT_100MS: Serial.println("100"); break;
    case VEML7700_IT_200MS: Serial.println("200"); break;
    case VEML7700_IT_400MS: Serial.println("400"); break;
    case VEML7700_IT_800MS: Serial.println("800"); break;
  }
  if (!SD.begin(SDpin)) {Serial.println("SD card failed."); 
    delay(50);exit(0);
  }
  Serial.println(F("SD card initialized."));  
  logfile=SD.open(filename,FILE_WRITE);   
  if (!logfile) {
    Serial.println(F("Couldn't create file.")); delay(50); exit(0);
  }  
  logfile.println(F("Date,Time,DayFrac,GA1A_raw,GA1A_V,GA1A_lux,lux,white,raw,lux_corrected")); logfile.flush();
}
void loop() {
  DateTime now=rtc.now();  // Get date and time.
  YR=now.year(); MON=now.month(); DAY=now.day();
  HR=now.hour(); MIN=now.minute(); SEC=now.second();
  dayFrac=DAY+HR/24.+MIN/1440.+SEC/86400.;  
  GA1A_raw=analogRead(GA1Apin); GA1A_V=range*GA1A_raw/1023;
  GA1A_lux=pow(10,GA1A_V);
  VEML_lux=veml.readLux(); VEML_white=veml.readWhite();
  VEML_raw=veml.readALS();
  lux_corrected=6.0135e-13*pow(VEML_lux,4)-9.3924e-9*pow(VEML_lux,3)+8.1488e-5*pow(VEML_lux,2)+1.0023*VEML_lux;
  white_corrected= 2E-15*pow(VEML_white,4) + 4E-12*pow(VEML_white,3) + 9E-06*pow(VEML_white,2) + 1.0179*VEML_white - 11.052;
  logfile.print(YR);                  logfile.print('/');
  logfile.print(MON);                 logfile.print('/');
  logfile.print(DAY);                 logfile.print(',');
  logfile.print(HR);                  logfile.print(':');
  logfile.print(MIN);                 logfile.print(':');
  logfile.print(SEC);                 logfile.print(','); 
  logfile.print(dayFrac,6);           logfile.print(',');   
  logfile.print(GA1A_raw);            logfile.print(',');
  logfile.print(GA1A_V,3);            logfile.print(',');
  logfile.print(GA1A_lux,1);          logfile.print(',');
  logfile.print(VEML_lux);            logfile.print(',');
  logfile.print(VEML_white,0);        logfile.print(',');
  logfile.print(VEML_raw);            logfile.print(',');
  logfile.print(lux_corrected);       logfile.print(',');
  logfile.println(white_corrected,0); logfile.flush();
  delay(delayTime);
}

Chapter 20.

Figure 20.5
/* UV_5.ino, D. Brooks, May 2019
  Compares analog output from Adafruit GUVA_S12SD UVA/B analog aensor board (ID 1918). 
  with Adafruit VEML6075 UVA/B/Index I2C senesor (ID 3964).
*/ 
#define ECHO_TO_SERIAL 1
#define ECHO_TO_FILE 1
#include <Wire.h>
#include <SD.h>
#include <RTClib.h> // Includes files for both old and new datalogging shield clocks.
#include "Adafruit_VEML6075.h"
Adafruit_VEML6075 uv = Adafruit_VEML6075();
RTC_DS1307 rtc; // real time clock module, old datalogger shield
// RTC_PCF8523 rtc;   // new datalogger shield
const int SDpin=10, UVpin=A1;
const long int delayTime=60000L;
float GUVA,VEML_UVA,VEML_UVB,VEML_UVIndex,dayFrac;
int GUVA_digitized;
File logfile;
char filename[]="UV_TEST.CSV";
int YR,MON,DAY,HR,MIN,SEC;
void setup() {
  pinMode(UVpin,INPUT); // for reading GUVA-S12SD UV sensor output  
  Serial.begin(9600); Wire.begin(); rtc.begin();
  //RTC.adjust(DateTime(__DATE__,__TIME__));  
  #if ECHO_TO_FILE 
    if (!SD.begin(SDpin)) {Serial.println(F("Card failed.")); delay(50); exit(0); }
    Serial.println(F("SD card initialized."));
    logfile = SD.open(filename, FILE_WRITE); 
    if (!logfile) { Serial.println(F("Couldn't create file.")); delay(50); exit(0); }  
    logfile=SD.open(filename,FILE_WRITE); Serial.println(F("Log file opened."));  
  #endif
  if (! uv.begin()) {
    Serial.println(F("Failed to communicate with VEML6075 sensor, check wiring?"));
  }
  Serial.println(F("Found VEML6075 sensor"));
  uv.setIntegrationTime(VEML6075_50MS);
  // Get the integration constant and print it!
  Serial.print(F("Integration time set to "));
  switch (uv.getIntegrationTime()) { // optional to display this value...
    case VEML6075_50MS:  Serial.print("50"); break;
    case VEML6075_100MS: Serial.print("100"); break;
    case VEML6075_200MS: Serial.print("200"); break;
    case VEML6075_400MS: Serial.print("400"); break;
    case VEML6075_800MS: Serial.print("800"); break;
  }
  Serial.println("ms");
  uv.setHighDynamic(false);  // Set the dynamic mode
  if (uv.getHighDynamic()) { // Get the mode
    Serial.println(F("High dynamic reading mode")); }
  else {
    Serial.println(F("Normal dynamic reading mode")); }
  uv.setForcedMode(false);   //Set the mode
  if (uv.getForcedMode()) {  //Get the mode, optional to display it...
    Serial.println(F("Forced reading mode")); }
  else {
    Serial.println(F("Continuous reading mode")); }
  // Set the calibration coefficients. For more ino about calculating UV index.
  // See Adafruit documentation and .cpp file. 
  // Don't change these coefficients for "bare" sensor.
  uv.setCoefficients(2.22, 1.33,  // UVA_A and UVA_B coefficients
                     2.95, 1.74,  // UVB_C and UVB_D coefficients
                     0.001461, 0.002591); // UVA and UVB responses
  #if ECHO_TO_SERIAL                  
    Serial.println(F("yr,mon,dy,hr,min,sec,day_frac,GUVA,VEML_UVA,VEML_UVB,VEML_UVIndex"));
  #endif
  #if ECHO_TO_FILE
    logfile.println(F("yr,mon,dy,hr,min,sec,day_frac,GUVA,VEML_UVA,VEML_UVB,VEML_UVIndex"));
    logfile.flush();
  #endif
}
void loop() {
  // Adafruit's Roithner GUVA sensor board  
  GUVA_digitized=analogRead(UVpin); delay(10); GUVA=5.*GUVA_digitized/1023.;      
  VEML_UVA=uv.readUVA(); VEML_UVB=uv.readUVB(); VEML_UVIndex=uv.readUVI();  
  DateTime now=rtc.now(); // Get date and time.
  YR=now.year(); MON=now.month(); DAY=now.day();
  HR=now.hour(); MIN=now.minute(); SEC=now.second();
  dayFrac=DAY+HR/24.+MIN/1440.+SEC/86400.;  
  #if ECHO_TO_FILE
    logfile.print(YR);               logfile.print(',');
    logfile.print(MON);              logfile.print(',');
    logfile.print(DAY);              logfile.print(',');
    logfile.print(HR);               logfile.print(',');
    logfile.print(MIN);              logfile.print(',');
    logfile.print(SEC);              logfile.print(',');
    logfile.print(dayFrac,6);        logfile.print(','); 
    logfile.print(GUVA,5);           logfile.print(',');
    logfile.print(VEML_UVA);         logfile.print(',');
    logfile.print(VEML_UVB);         logfile.print(',');
    logfile.println(VEML_UVIndex,2); logfile.flush(); 
  #endif 
  #if ECHO_TO_SERIAL
    Serial.print(YR);        Serial.print(',');
    Serial.print(MON);       Serial.print(',');
    Serial.print(DAY);       Serial.print(',');
    Serial.print(HR);        Serial.print(',');
    Serial.print(MIN);       Serial.print(',');
    Serial.print(SEC);       Serial.print(','); 
    Serial.print(dayFrac,6); Serial.print(',');
    Serial.print(GUVA,5);    Serial.print(',');
    Serial.print(VEML_UVA);  Serial.print(',');
    Serial.print(VEML_UVB);  Serial.print(','); 
    Serial.println(VEML_UVIndex,2); 
  #endif     
  delay(delayTime);
}

Figure 20.9
// VEML6075_TFT.ino, D. Brooks, May 2019
//  Displays UV Index on an ID 2088 Adafruit TFT screem. 
#include <Wire.h>
#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_ST7735.h> // Hardware-specific library
#include <SPI.h>
#include <Adafruit_VEML6075.h>
Adafruit_VEML6075 uv = Adafruit_VEML6075();
#define TFT_CS     10
#define TFT_RST    9  
#define TFT_DC     8
#define BLACK 0x0000
#define WHITE 0xFFFF
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS,TFT_DC,TFT_RST);
const long int delayTime=2000L;
void setup(void) {
  Serial.begin(9600);
  if (! uv.begin()) {
    Serial.println(F("Failed to communicate with VEML6075 sensor, check wiring?"));
  }
  uv.setHighDynamic(false); uv.setIntegrationTime(VEML6075_50MS);
  uv.setForcedMode(false);
  uv.setCoefficients(2.22, 1.33,  // UVA_A and UVA_B coefficients // no Teflon sensor cover
                     2.95, 1.74,  // UVB_C and UVB_D coefficients
                     0.001461, 0.002591); // UVA and UVB responses
  Serial.println(F("Found VEML6075 sensor")); 
  tft.initR(INITR_144GREENTAB); // initialize a ST7735S chip, green tab
  Serial.println("TFT Initialized"); tft.fillScreen(BLACK);
  tft.setTextColor(WHITE); tft.setTextSize(2); 
}
void loop() { 
  tft.fillScreen(BLACK); tft.setCursor(2,2);
  tft.println("UV Index:"); tft.setCursor(2,30);
  tft.println(uv.readUVI()); delay(delayTime);  
}

Chapter 21.

Figure 21.6
// StringToNumber.ino, D. Brooks, August 2019
char s1[5],s2[4],s3[6];
float x=12.5,y=6.6,z=15.89; int i;
char S[14],S1[5],S2[4],S3[6];
void setup() {
  Serial.begin(9600);

  Serial.println("Original data values: ");
  Serial.print(x,1); Serial.print(',');
  Serial.print(y,1); Serial.print(',');
  Serial.print(z,2); Serial.println();
  // Convert numbers to packet string.
  // 5+1+4+1+6+1
  char S[14],S1[5],S2[4],S3[6];
  dtostrf(x,4,1,S1); dtostrf(y,3,1,S2);
  dtostrf(z,5,2,S3);
  for (i=0; i<=3; i++) { S[i]=S1[i]; }
  S[4]=',';
  for (i=5; i<=7; i++) { S[i]=S2[i-5]; }
  S[8]=',';
  for (i=9; i<=13; i++) { S[i]=S3[i-9]; }
  S[14]='\0';
  Serial.print("packet string: ");
  Serial.println(S);
  for (i=0; i<=3; i++) { s1[i]=S[i]; }
  s1[i]='\0';
  for (i=5; i<=7; i++) { s2[i-5]=S[i]; }
  s2[i]='\0';
  for (i=9; i<=13; i++) { s3[i-9]=S[i]; }
  s1[3]='\0';
  x=atof(s1); y=atof(s2); z=atof(s3);
  Serial.println("values extracted from packet string: ");
  Serial.print(x,1); Serial.print(',');
  Serial.print(y,1); Serial.print(',');
  Serial.println(z,2);
}
void loop() {
}

Figure 21.8
/*  PacketRadio915_AM2315_BME280_TX.ino,  D.  Brooks,  January  2018 
     Sends  data  from  AM2315  T/RH  and  BME280  T/RH/P  sensors. 
     Puts  all  the  TX  code  in  the  setup()  function.  Turns  system  on  to  collect  data 
     and  send  packet,  then  turns  system  off  upon  receipt  of  "done"  signal  from 
     Pro  Mini  Board,  using  the  TPL5110  low  power  module  from  adafruit.com.  
*/ 
// setup for AM2315
#include <Wire.h>
#include <Adafruit_AM2315.h>
Adafruit_AM2315 am2315;
float am2315_T,am2315_H;
#include <SPI.h>
#include <RH_RF69.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BME280.h>  
Adafruit_BME280 bme;
float T_BME,RH_BME,P_BME,P_inHg;
// TX Radio Setup
#define RF69_FREQ 900.0 // RX must match this frequency.
#define RFM69_INT     3  // for UNO
#define RFM69_CS      4  //
#define RFM69_RST     2  //
// The encryption key has to be the same as the one in the receiver.
uint8_t key[] = { 0x11, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
                  0x11, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08
                };
RH_RF69 rf69(RFM69_CS, RFM69_INT); // Instantiate radio driver.
int i;
const int donePIN=5;
char AMTString[7],AMRHString[7],T_BMEString[7],RH_BMEString[7],P_BMEString[7];
char RadioPacket[40],P_inHgString[6];
void setup()
{
  pinMode(donePIN,OUTPUT); digitalWrite(donePIN,LOW);
  Serial.begin(9600); bme.begin(); am2315.begin();
  Serial.println("sensors initiated");
  pinMode(RFM69_RST, OUTPUT); digitalWrite(RFM69_RST, LOW);
  // manual reset TX
  digitalWrite(RFM69_RST, HIGH); delay(10);
  digitalWrite(RFM69_RST, LOW); delay(10);
  if (!rf69.init()) {
    Serial.println("RFM69 radio init failed");
    while (1);
  }
  Serial.println("RFM69 radio init OK!");
  // Defaults after init are 434.0MHz, modulation GFSK_Rb250Fd250, +13dbM (for low power module)
  // No encryption
  if (!rf69.setFrequency(RF69_FREQ)) {
    Serial.println("setFrequency failed");
  }
  rf69.setTxPower(20, true);  // range from 14-20 for power, 2nd arg must be true for 69HCW
  rf69.setEncryptionKey(key);
  Serial.print("RFM69 radio @");  Serial.print((int)RF69_FREQ);  Serial.println(" MHz");
  // read AM2315
  am2315_T=am2315.readTemperature(); am2315_H=am2315.readHumidity();  
  delay(10);  T_BME=bme.readTemperature();
  delay(10); RH_BME=bme.readHumidity(); delay(10); P_BME=bme.readPressure(); delay(10);
  // Add pressure conversion to inches Hg. Mysite elevation is 131 m.
  // The formula needs elevation in km.
  P_inHg=(P_BME/100.)/exp(-0.119*0.131-0.0013*0.131*0.131); // mbar to sea level
  P_inHg*=29.921/1013.25; // to in Hg  
  Serial.println("Values...");
  Serial.print(P_BME/100.);Serial.print(',');
  Serial.println(P_inHg,2);
  Serial.print(am2315_T,2); Serial.print(',');Serial.print(am2315_H,2); 
  Serial.print(',');Serial.print(T_BME,2); 
  Serial.print(',');Serial.print(RH_BME,2);Serial.print(',');
  Serial.println(P_BME/100.,1);
  dtostrf(P_inHg,5,2,P_inHgString);  
  dtostrf(am2315_H,6,2,AMRHString); dtostrf(am2315_T,6,2,AMTString); 
  dtostrf(RH_BME,6,2,RH_BMEString); 
  dtostrf(T_BME,6,2,T_BMEString); dtostrf(P_BME/100.,6,1,P_BMEString); 
  Serial.println("Strings...");
  Serial.print(AMTString);Serial.print(',');Serial.print(AMRHString);
  Serial.print(',');
  Serial.print(T_BMEString);Serial.print(',');Serial.print(RH_BMEString);Serial.print(',');
  Serial.print(P_BMEString);Serial.print(',');
  Serial.println(P_inHgString);
  for (i = 0; i <= 5; i++) { RadioPacket[i] = AMTString[i]; }
  RadioPacket[6] = ','; 
  for (i = 7; i <= 12; i++) { RadioPacket[i] = AMRHString[i - 7];} RadioPacket[13]=',';
  for (i=14; i<=19; i++) { RadioPacket[i]=T_BMEString[i-14];} RadioPacket[20]=',';
  for (i=21; i<=26; i++) { RadioPacket[i]=RH_BMEString[i-21]; } RadioPacket[27]=',';
  for (i=28; i<=33; i++) { RadioPacket[i]=P_BMEString[i-28]; } RadioPacket[34]=',';
  for (i=35; i<=39; i++) {RadioPacket[i]=P_inHgString[i-35];} RadioPacket[40] = '\0';  
  rf69.send((uint8_t *)RadioPacket, strlen(RadioPacket)); rf69.waitPacketSent();
  // Now wait for a reply
  uint8_t buf[RH_RF69_MAX_MESSAGE_LEN]; uint8_t len = sizeof(buf);
  if (rf69.waitAvailableTimeout(500))  {
    // Should be a reply message for us now
    if (rf69.recv(buf, &len)) {
      Serial.print("Got a reply: "); Serial.println((char*)buf);
    } 
    else { Serial.println("Receive failed"); }
  } else {
    Serial.println("No reply, is another RFM69 listening?");
  }
  delay(50); digitalWrite(donePIN,HIGH); // turn off power 
}
void loop() {
}

Figure 21.9
/* PacketRadio915_AM2315_BME280_RX.ino, D. Brooks, August 2018
   A modification of the example RX code for the RH-RF69 packet radio module.
   Receives a text string from the TX module (see TX_LowPower_TRHP.ino).
   Formats it for display on a SunFounder 20x4 LCD and saves with date/time stamp
   on an SD card, using Adafruit datalogging shield.
*/
#include <SPI.h>
#include <Wire.h>
#include <SD.h>
#include <RTClib.h>
#include <LiquidCrystal_I2C.h> // from sunfounder.com
#include <RH_RF69.h>
#define RF69_FREQ 900.0
#define SDpin 10
#define RFM69_INT     3   
#define RFM69_CS      4  
#define RFM69_RST     2  
RTC_DS1307 rtc; LiquidCrystal_I2C lcd(0x27,20,4); 
RH_RF69 rf69(RFM69_CS, RFM69_INT);
int i; File logfile; char filename[]="LOG00000.CSV";
//char P_inHg[]="xx.xx";
void setup() 
{
  Serial.begin(9600); SD.begin(); Wire.begin(); rtc.begin();
  rtc.adjust(DateTime(__DATE__,__TIME__));  // only when connected to computer!
  Serial.print("Current time: ");
  DateTime now=rtc.now();
      Serial.print(now.year()); Serial.print('/');
      Serial.print(now.month()); Serial.print('/');
      Serial.print(now.day()); Serial.print(' ');
      Serial.print(now.hour()); Serial.print(':');
      Serial.print(now.minute()); Serial.print(':');
      Serial.print(now.second()); Serial.println();  
  logfile=SD.open(filename,FILE_WRITE);
  // Setup for 20x4 SunFounder LCD
  lcd.init(); lcd.backlight(); lcd.clear();
  lcd.setCursor(0,0); lcd.print("LCD setup...");    
  pinMode(RFM69_RST, OUTPUT); digitalWrite(RFM69_RST, LOW);
  // manual reset
  digitalWrite(RFM69_RST, HIGH); delay(10);
  digitalWrite(RFM69_RST, LOW); delay(10); 
  if (!rf69.init()) {
    Serial.println("RFM69 radio init failed");
    while (1);
  }
  Serial.println("RFM69 radio init OK!");
  if (!rf69.setFrequency(RF69_FREQ)) {
    Serial.println("setFrequency failed");
  }
  rf69.setTxPower(20, true);  // range from 14-20 for power, 
  // The encryption key has to be the same as the one in the TX.
  uint8_t key[] = { 0x11, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
                    0x11, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08};
  rf69.setEncryptionKey(key);
  Serial.print("RFM69 radio @"); Serial.print((int)RF69_FREQ);  
  Serial.println(" MHz");
}
void loop() {
 if (rf69.available()) {
     DateTime now=rtc.now();
     logfile.print(now.day()+now.hour()/24.+now.minute()/1440.+now.second()/86400.,6);
     logfile.print(','); 
    // Should be a message for us now   
    uint8_t buf[RH_RF69_MAX_MESSAGE_LEN]; uint8_t len = sizeof(buf);
    if (rf69.recv(buf, &len)) {
      if (!len) return;
      buf[len] = 0; Serial.println(); 
      lcd.clear(); lcd.setCursor(0,0); lcd.print("AM2 T/RH ");
      for (i=0; i<=5; i++) {
        Serial.print((char)buf[i]); lcd.print((char)buf[i]);
        logfile.print((char)buf[i]);
      }
      Serial.print(','); logfile.print(',');
      for (i=7; i<=12; i++) {
        Serial.print((char)buf[i]); lcd.print((char)buf[i]); 
        logfile.print((char)buf[i]);
      }
      Serial.print(','); logfile.print(',');
      lcd.setCursor(0,1); lcd.print("BME T/RH ");
      for (i=14; i<=19; i++) {
        Serial.print((char)buf[i]); lcd.print((char)buf[i]); 
        logfile.print((char)buf[i]);             
      }
      Serial.print(','); logfile.print(',');
      for (i=21; i<=26; i++) {
        Serial.print((char)buf[i]); lcd.print((char)buf[i]); 
        logfile.print((char)buf[i]);               
      }
      Serial.print(','); logfile.print(',');
      lcd.setCursor(0,2); lcd.print("BME P ");      
      //char Pstring[7];
      for (i=28; i<=33; i++) {
        Serial.print((char)buf[i]); 
        //Pstring[i-28]=(char)buf[i];
        lcd.print((char)buf[i]);
        logfile.print((char)buf[i]);
      }
      lcd.print(' '); lcd.print(' ');
      for (i=35; i<=39; i++) {
        lcd.print((char)buf[i]);
        //lcd.print(P_inHg[i-35]);
      }
      Serial.println(); logfile.print(','); 
      logfile.print(now.year()); logfile.print(',');
      logfile.print(now.month()); logfile.print(',');
      logfile.print(now.day()); logfile.print(',');
      logfile.print(now.hour()); logfile.print(',');
      logfile.print(now.minute()); logfile.print(',');
      logfile.print(now.second()); logfile.print(',');      
      logfile.println(); logfile.flush(); 
      lcd.setCursor(0,1); lcd.setCursor(0,3);
      lcd.print(now.year()); lcd.print('/');
      lcd.print(now.month()); lcd.print('/');
      lcd.print(now.day()); lcd.print(' ');
      lcd.print(now.hour()); lcd.print(':');
      lcd.print(now.minute()); lcd.print(':');
      lcd.print(now.second()); 
    } else {
      lcd.print("Receive failed");
    }
  }
}

Figure 21.13
/*  433_DHT_TX.ino,  D.  Brooks,  December  2019 
    TX  with  Pro  Mini.  
    Reads  DHT22  data  from  pin  D8.  
*/ 
#include  <RH_ASK.h> 
#include  <SPI.h> 
RH_ASK  rf_driver; 
#include  <DHT.h> 
#define  DHTPIN  8 
#define  DHTTYPE  DHT22 
DHT  dht(DHTPIN,DHTTYPE); 
float  h,t; 
char  TS[6],HS[6],S[12]; 
const  int  j; 
int  i; 
void  setup()  { 
    rf_driver.init(); 
    Serial.begin(9600);  
    dht.begin();    
} 
void  loop()  { 
    t=dht.readTemperature();  h=dht.readHumidity(); 
    Serial.print(t,1);  Serial.print(',');  Serial.println(h,1);    
    dtostrf(t,5,1,TS);  dtostrf(h,5,1,HS);  
    for  (i=0;  i<=4;  i++)  { 
        S[i]=TS[i]; 
    } 
    S[5]=','; 
    for  (i=6;  i<=10;  i++)  { 
        S[i]=HS[i-6]; 
    } 
    S[11]='\0';      
    const  char  *packet=S; 
    rf_driver.send((uint8_t  *)packet,strlen(packet)); 
    rf_driver.waitPacketSent(); 
    Serial.print("Packet  sent:  "); 
    Serial.println(S);  
    delay(2000); 
}

Chapter 22.

Figure 22.3
/* Feather_SD.ino, D. Brooks, May 2019
  Save date/time and TMP36 data to SD card.
*/
#include <SPI.h>
#include <Wire.h>
#include <RTClib.h>
#include <SD.h>
#define cardSelect 4
RTC_PCF8523 rtc;
File logfile;
char filename[]="SDLOGGER.CSV";
int YR,MON,DAY,HR,MIN,SEC;
const int TMP36pin=A0;
const long int delayTime=60000L;
float T;
void setup () {
  Serial.begin(9600);
  if (! rtc.begin()) {
    Serial.println("Couldn't find RTC");
    while (1);
  }
  if (! rtc.initialized()) {
    Serial.println("RTC is NOT running!");
    // following line sets the RTC to the date & time this sketch was compiled
     rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
    // rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
  }  
  if (!SD.begin(cardSelect)) {
    Serial.println("Card init. failed!");
  }
  logfile=SD.open(filename,FILE_WRITE);
  Serial.print("Writing to "); Serial.println(filename);  
  if (! rtc.initialized()) {
    Serial.println("RTC is NOT running!");
    // following line sets the RTC to the date & time this sketch was compiled
     rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
    // This line sets the RTC with an explicit date & time, for example to set
    // January 21, 2014 at 3am you would call:
    // rtc.adjust(DateTime(2014, 1, 21, 3, 0, 0));
  }
}
void loop () {
  T=3.3*analogRead(TMP36pin)/1023.; T=100.*(T-0.5);
  DateTime now = rtc.now();
  YR=now.year(); MON=now.month(); DAY=now.day();
  HR=now.hour(); MIN=now.minute(); SEC=now.second();
  Serial.print(YR); Serial.print('/');
  Serial.print(MON); Serial.print('/');
  Serial.print(DAY); Serial.print(' ');
  Serial.print(HR); Serial.print(':');
  Serial.print(MIN); Serial.print(':');
  Serial.print(SEC); Serial.print(' ');
  Serial.print(DAY+HR/24.+MIN/1440.+SEC/86400.,6); Serial.print(' ');
  Serial.println(T,2);      
  logfile.print(YR); logfile.print(',');
  logfile.print(MON); logfile.print(',');
  logfile.print(DAY); logfile.print(',');
  logfile.print(HR); logfile.print(',');
  logfile.print(MIN); logfile.print(',');
  logfile.print(SEC); logfile.print(',');
  logfile.print(DAY+HR/24.+MIN/1440.+SEC/86400.,6); logfile.print(',');
  logfile.println(T,2); logfile.flush();
  delay(delayTime);
}

Appendix 1.

Figure A1.1
/* float_math.ino. D. Brooks, March 2019
  Demonstrates time required for integer
  and real number calculations.
 */
 int i,y;
unsigned long int time1,time2;
float Y;
void setup() {
  Serial.begin(9600);
  float x=3.3, y=7.0;
  Serial.println(x*y,8);
  if (x*y == 23.1) Serial.println("equality!");
  else Serial.println("not euite equal");
  Serial.println(25./3.,8);
  if ((abs(x*y)-23.1)<1e-6) Serial.println("equal");
  time1=micros();
  Serial.print("time 1 ");Serial.println(time1);
  for (i=1; i<=5000; i++) {
    y=5*5;
  }
  time2=micros();
  Serial.print("time 2 ");Serial.println(time2);
  Serial.println(time2-time1);
  time1=micros();
  Serial.print("time 1 ");Serial.println(time1);  
  for (i=1; i<=5000; i++) {
    Y=5.*5.;
  }
  time2=micros();
  Serial.print("time 2 ");Serial.println(time2); 
  Serial.println(time2-time1);   
}
void loop() {
}

Appendix 4.

Figure A4.1
/* NormalDistribution.ino, Feb. 2019, D. Brooks
  Generates some normally distributed numbers and 
  calculates min, max, mean, and standard deviation,
  assuming the range of values is never more than
  +/-1000.
*/
long u1,u2;
float U1,U2,Theta,N1,N2;
float sumX=0.,sumXX=0.,mean,stdDev;
float minX=1000.,maxX=-1000.;
int N=40;
void setup() {
  Serial.begin(9600); randomSeed(analogRead(0));
  for (int i=1; i<=N; i++) {
    // Generate 2N normally distributed numbers
    // using the Box-Muller transform.
    u1=random(0,1000); u2=random(0,1000);
    U1=u1/1000.; U2=u2/1000.;
    // It's possible that U1 or U2 could be 0, for
    // which the log doesn't exist. Fix it...    
    if (U1==0) U1=.001; if (U2==0) U2=.001;
    Theta=2*M_PI*U2;
    N1=sqrt(-2*log(U1))*cos(Theta); 
    N2=sqrt(-2*log(U1))*sin(Theta);
    sumX=sumX+N1+N2;
    sumXX=sumXX+N1*N1+N2*N2;   
    if (N1>maxX) maxX=N1; if (N2>maxX) maxX=N2;
    if (N1<minX) minX=N1; if (N2<minX) minX=N2; 
    Serial.print(u1); Serial.print(',');
    Serial.print(u2); Serial.print(',');
    Serial.print(U1); Serial.print(',');
    Serial.print(U2); Serial.print(',');
    Serial.print(N1); Serial.print(',');
    Serial.print(N2); Serial.println();
  }
  Serial.println("---------------");
  mean=sumX/2./N;
  stdDev=sqrt((sumXX-sumX*sumX/2./N)/(2.*N-1));
  Serial.print("Mean, StdDev, Min, Max: ");
  Serial.print(mean);   Serial.print(',');
  Serial.print(stdDev); Serial.print(',');
  Serial.print(minX);   Serial.print(',');
  Serial.println(maxX);  
}
void loop() {}

Appendix A5.

Figure A5.1
// InternalReference.ino, code 
// check internal refernce voltage
void setup() {
analogReference(INTERNAL);
}
void loop() {
 int i=analogRead(A0);
 delay(50);
}

Figure A5.2
/* TMP_IntRef.ino, D. Brooks, June 2019
  Assumes TMP36 or compatible analog temperature sensor.
  Uses 1.1 V internal reference voltage.
*/
const int TMPpin1=A0,TMPpin2=A1;
int V_digitized1,V_digitized2, delayTime=3000; 
float V_analog1,V_analog2,T1,T2; // temperature in deg C
void setup() {
  pinMode(TMPpin1,INPUT); pinMode(TMPpin2,INPUT);  
  Serial.begin(9600);
  analogReference(INTERNAL);
}
void loop() {
  V_digitized1=analogRead(TMPpin1); 
  V_digitized1=analogRead(TMPpin1); 
  V_analog1=1.1*V_digitized1/1023;  
  T1=100*V_analog1; 
  V_digitized2=analogRead(TMPpin2); 
  V_digitized2=analogRead(TMPpin2); 
  V_analog2=1.1*V_digitized2/1023;  
  T2=100*V_analog2;  
  Serial.print(T1,2); Serial.print(' ');
  Serial.println(T2,2); 
  delay(delayTime);
}