我決定自行編寫範例程式，來說明如何將 Arduino 設為睡眠狀態。你可能會感到疑惑，有這麼必要呢？答案是，如果你正在製作的項目是以電池供電的話，那麼這個示例將會非常實用。讓 Arduino 進入睡眠模式狀態可降低電流消耗，從而延長項目的運作時間，而不必頻繁更換電池。在許多 IOT 項目中亦是如此，因為並不需要微控制器或外部器件一直保持運作。
在開始範例程式碼前，先簡單介紹，我們用了兩個按鈕和兩個 LED 來顯示何時喚醒電路板以及何時按下中斷按鈕。當電路板被喚醒時，連接到引腳 13 的 LED 將開始閃爍。當按下連接到引腳 11 的按鈕時，將使 Arduino 進入睡眠模式，而引腳 13 的 LED 也將停止閃爍。要喚醒電路板，只需按下連接到引腳 2 的按鈕即可。按下此按鈕時，連接到引腳 10 的 LED 將亮起，以表示中斷已被致動。
啟動範例程式碼
//These are the two libraries that are needed
#include <avr/interrupt.h>
#include <avr/sleep.h>
/* Here we set up our inputs and outputs. LEDs connected to pins 10 and 13 and pushbuttons attached to 2 and 12 */
int ledPin = 13;
int sleepPin = 12;
int interruptPin = 10;
int wakePin = 2;
//sleepStatus is set up to keep track of the button input on pin 12.
int sleepStatus = 0;
void setup()
{
pinMode(ledPin, OUTPUT);
pinMode(interruptPin, OUTPUT);
pinMode(sleepPin, INPUT_PULLUP);
pinMode(wakePin, INPUT_PULLUP);
/* Next we have to enable an interrupt.
The function is set up like this attachInterrupt(pin, function, triggerMode)
PIN – can be either a 0 to call out digital pin 2 or 1 to call out digital pin 3.
FUNCTION – This is the function that will be run while in the interrupt
TRIGGER MODE – this will be the mode of the interrupt pin.
It can be one the following:
LOW – a low level trigger
CHANGE – a change in level trigger
RISING – a rising edge trigger
FALLING – a falling edge trigger
The IDLE sleep mode is the only mode that can use CHANGE, RISING, and FALLING modes.*/
attachInterrupt(0, wakeUpNow, LOW);
}
void sleepNow()
{
//print message to serial monitor to let the user know board has gone to sleep
Serial.println("going to sleep");
//delay is added to allow user to get the full message on the serial monitor before going to sleep
delay(15);
//enables the sleep mode
sleep_enable();
// This is where we enable the interrupt, the reason it is done here is so that if the button is pressed accidently it doesn’t interrupt the running program.
attachInterrupt(0,wakeUpNow, LOW);
/* The next line is where we choose the sleep mode we want to use for this code. There are a few options to choose from, each with their own uses. For more information on the sleep modes, please review the Atmega8 datasheet at [http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf](http://ww1.microchip.com/downloads/en/DeviceDoc/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061A.pdf)
The 5 different options for sleep modes, they are listed below from least power savings to most power savings:
SLEEP_MODE_IDLE
SLEEP_MODE_ADC
SLEEP_MODE_PWR_SAVE
SLEEP_MODE_STANDBY
SLEEP_MODE_PWR_DOWN
For this sketch, we will be using the most power savings possible so we choose SLEEP_MODE_PWR_DOWN */
//sleep mode is set here
set_sleep_mode(SLEEP_MODE_PWR_DOWN);
//This is where the device is actually put to sleep
sleep_mode();
//Here is where the device begins to wake up.
//First thing that is done is to disable the sleep mode
sleep_disable();
//disables the interrupt on pin 2 so the wakeUpNow code will not be executed during normal run time
detachInterrupt(0);
//wait 1 second so the user can notice the LED signaling the interrupt
delay(1000);
digitalWrite (interruptPin, LOW);
}
void wakeUpNow() //This is the code that runs when the interrupt button is pressed and interrupts are enabled
{
digitalWrite(interruptPin, HIGH);
}
void loop()
{
// turns the LED on
digitalWrite(ledPin, HIGH);
// waits for a second
delay(1000);
// turns the LED off
digitalWrite(ledPin, LOW);
// waits for a second
delay(1000);
//This is where the sleep pin is read. It is only active when the LED is off.
sleepStatus = digitalRead(sleepPin);
//If button is pressed, device will run the sleepNow function
if (sleepStatus == LOW) {
sleepNow();
}
}
原始碼接線圖
鏈結到 Scheme-It 原理圖：https://www.digikey.com/schemeit/project/arduino-uno-7FSP1FG40120/
加入即時時脈來喚醒 Arduino
接下來，我們將加入一個 RTC（而非按鈕）來控制 Arduino 的睡眠模式和喚醒。我在此項目中使用的是來自 Adafruit 的1528-1598-ND（Product ID: 3013） 。選擇它的主要原因是其配備了內置中斷。我原來使用的是 DS1307 分接板，但我很快發現它並不支持中斷，因此無法用於此項目。我還針對此項目下載了一些庫。以下是指向我下載 .zip 庫文件的超鏈結。
指向庫的超鏈結：
GitHub - PaulStoffregen/Time: Time library for Arduino - 這是 Arduino 的計時庫
GitHub - JChristensen/DS3232RTC: Arduino Library for Maxim Integrated DS3232 and DS3231 Real-Time Clocks - 這庫適用於 DS3231，包含喚醒 Arduino 所需的警報
加入 RTC 的程式碼
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <DS3232RTC.h> // https://github.com/JChristensen/DS3232RTC this is the library for the DS2331 RTC
//RTC Module global variables
// Sets the wakeup interval in minutes
const int time_interval = 5;
// LED connected to digital pin 13
int ledPin = 13;
// active LOW, RTC will interrupt this pin momentarily to wake up
int wakePin = 2;
void setup() {
// set up the serial monitor
Serial.begin(9600);
//Set up the led pin as an output
pinMode(ledPin, OUTPUT);
//Set pin d2 to input using the built-in pullup resistor
pinMode(wakePin, INPUT_PULLUP);
//turning LED on
digitalWrite(ledPin, HIGH);
// These next few lines of code initialize the alarms to known values, clear the flags, and clear the alarm interrupt flags
RTC.setAlarm(ALM1_MATCH_DATE, 0, 0, 0, 1);
RTC.setAlarm(ALM2_MATCH_DATE, 0, 0, 0, 1);
RTC.alarm(ALARM_1);
RTC.alarm(ALARM_2);
RTC.alarmInterrupt(ALARM_1, false);
RTC.alarmInterrupt(ALARM_2, false);
RTC.squareWave(SQWAVE_NONE);
/* Uncomment this section to set the time on the RTC. Make sure to comment out after the first time
it is set or you will continue to reset the time everytime the sketch is uploaded. Also note that the clock is 24 hour format.
tmElements_t tm;
// the next few lines set the clock to the correct hour, minute, and second. Remember 24 hour format so 4pm = hour 16
tm.Hour = 8;
tm.Minute = 19;
tm.Second = 00;
// set the correct date on the RTC
tm.Day = 04;
tm.Month = 5;
tm.Year = 2019 - 1970; // in order to set the year correctly, just change the 2019 and leave the “- 1970” to get the correct offset
RTC.write(tm); // write the date and time to the RTC
*/
time_t t; //create a temporary time variable so we can set the time and read the time from the RTC
t = RTC.get(); //Gets the current time of the RTC
RTC.setAlarm(ALM1_MATCH_MINUTES , 0, minute(t) + time_interval, 0, 0); // Setting alarm 1 to go off in the amount of minutes that we have the time interval constant set to
RTC.alarm(ALARM_1); // clear the alarm flag
RTC.squareWave(SQWAVE_NONE); // configure the INT/SQW pin for "interrupt" operation (disable square wave output)
RTC.alarmInterrupt(ALARM_1, true); // enable interrupt output for Alarm 1
}
void loop() {
delay(5000);//wait 5 seconds before going to sleep. When in a project, we would it is best to make this short as possible
sleepNow(); // run the sleepNow function
}
void sleepNow() {
sleep_enable();//Enabling sleep mode
attachInterrupt(0, wakeUpNow, LOW);//attaching a interrupt to pin d2
set_sleep_mode(SLEEP_MODE_PWR_DOWN);//Setting the sleep mode, in our case full sleep
digitalWrite(ledPin, LOW); //turning LED off
time_t t;// creates temporary time variable
t = RTC.get(); //gets current time from RTC
Serial.println("Sleep Time: " + String(hour(t)) + ":" + String(minute(t)) + ":" + String(second(t))); //prints time stamp on serial monitor
delay(1000); //wait one second to allow the LED to be turned off before going to sleep
sleep_cpu();//heres where the Arduino is actually put to sleep
Serial.println("just woke up!");//next line of code executed after the interrupt
digitalWrite(ledPin, HIGH); //turns the LED on
t = RTC.get();//get the new time from the RTC
Serial.println("WakeUp Time: " + String(hour(t)) + ":" + String(minute(t)) + ":" + String(second(t))); //Prints time stamp
//Set New Alarm
int alarmTime = 0; //temporary variable to store the new alarm time in minutes
//the next few lines are to roll the alarm over when it gets near the next hour
if (minute(t) <= (60-time_interval))
{
alarmTime = minute(t) + time_interval;
}
else
{
alarmTime = (minute(t) + time_interval) - 60;
}
RTC.setAlarm(ALM1_MATCH_MINUTES , 0, alarmTime, 0, 0); // set new alarm
// The next few lines of code I use for troubleshooting. This way I can make sure the clock is waking up at the correct time
Serial.print("The next alarm will go off at: ");
//These lines are to print the correct hour that the next alarm will go off
if ((minute(t) <= 60-time_interval) && (hour(t) <= 22))
{
Serial.print(hour(t));
}
else if ((minute(t) >= 60-time_interval) && (hour(t) <= 22))
{
Serial.print(hour(t) + 1);
}
else
{
Serial.print(0);
}
Serial.print(":"); // print a colon symbol
//print the correct minute, including leading zero if less than 10
if (alarmTime <= 9)
{
Serial.print("0");
}
Serial.println(alarmTime);
//Last thing we do is clear the alarm flag
RTC.alarm(ALARM_1);
}
void wakeUpNow() //This is the code that happens when the interrupt is activated
{
Serial.println("Interrrupt Fired");//Print message to serial monitor
sleep_disable();//Disable sleep mode
detachInterrupt(0); //Removes the interrupt from pin 2;
}
RTC 接線圖
鏈結接到 Scheme-It 原理圖： https://www.digikey.com/schemeit/project/arduino-uno-rtc-sleep-TKBAG6G400UG/
加入土壤濕度感測器和溫度 / 濕度感測器
為了展示這類傳感器的使用範例，我決定製作一個獨立的裝置監控系統。為此，我將使用土壤濕度探針（1568-1670-ND﹐SparkFun SEN-13637 ）和溫度/濕度感測器（1528-1172-ND，Adafruit 992）。該程序現在要做的是檢查土壤水份含量和溫度。我決定省略此編碼草稿中的濕度功能，但只需幾行編碼就可以重新加入。
此監控系統會進行檢查，以確保土壤濕度不會過低。如果水分含量低於一定水平，系統就會啟動水泵或電磁閥。在本範例中，我將 LED 用作指示器，以代替水泵或電磁閥。
對於此編碼草稿，你需要安裝 MPL115A2 庫，該庫可通過 Manage Libraries Button 進行安裝（位於 Include Library 下的 Sketch Menu 中），或者你也可以通過以下鏈接找到 zip 文件：GitHub - adafruit/Adafruit_MPL115A2: Driver for the Adafruit MPL115A2 barometric pressure sensor breakout
加入溫度 / 濕度感測器和土壤濕度感測器的程式碼
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <DS3232RTC.h> // https://github.com/JChristensen/DS3232RTC this is the library for the DS2331 RTC
#include <Wire.h>
#include <Adafruit_MPL115A2.h>
Adafruit_MPL115A2 mpl115a2;
//RTC Module global variables
// Sets the wakeup interval in minutes
const int time_interval = 5;
// LED connected to digital pin 13
int ledPin = 13;
// active LOW, RTC will interrupt this pin momentarily to wake up
int wakePin = 2;
// LED connected to digital pin 10
int pumpLED = 10;
//variable for storing the soil moisture value
int moistureVal = 0;
//input for the moisture sensor
int soilPin = A0;
//pin used to power the soil moisture sensor
int soilPower = 7;
void setup() {
// set up the serial monitor
Serial.begin(9600);
//Set up the led pin as an output
pinMode(ledPin, OUTPUT);
//Set pin d2 to input using the built-in pullup resistor
pinMode(wakePin, INPUT_PULLUP);
//turning LED on
digitalWrite(ledPin, HIGH);
//Set D7 as an OUTPUT
pinMode(soilPower, OUTPUT);
// Set to LOW so no power is flowing through the sensor
digitalWrite(soilPower, LOW);
//Set D10 as an output
pinMode(pumpLED, OUTPUT);
//starting the temp/humidity sensor
mpl115a2.begin();
// These next few lines of code initialize the alarms to known values, clear the flags, and clear the alarm interrupt flags
RTC.setAlarm(ALM1_MATCH_DATE, 0, 0, 0, 1);
RTC.setAlarm(ALM2_MATCH_DATE, 0, 0, 0, 1);
RTC.alarm(ALARM_1);
RTC.alarm(ALARM_2);
RTC.alarmInterrupt(ALARM_1, false);
RTC.alarmInterrupt(ALARM_2, false);
RTC.squareWave(SQWAVE_NONE);
/* Uncomment this section to set the time on the RTC. Make sure to comment out after the first time
it is set or you will continue to reset the time everytime the sketch is uploaded. Also note that the clock is 24 hour format.
tmElements_t tm;
// the next few lines set the clock to the correct hour, minute, and second. Remember 24 hour format so 4pm = hour 16
tm.Hour = 8;
tm.Minute = 19;
tm.Second = 00;
// set the correct date on the RTC
tm.Day = 04;
tm.Month = 5;
tm.Year = 2019 - 1970; // in order to set the year correctly, just change the 2019 and leave the “- 1970” to get the correct offset
RTC.write(tm); // write the date and time to the RTC
*/
time_t t; //create a temporary time variable so we can set the time and read the time from the RTC
t = RTC.get(); //Gets the current time of the RTC
RTC.setAlarm(ALM1_MATCH_MINUTES , 0, minute(t) + time_interval, 0, 0); // Setting alarm 1 to go off in the amount of minutes that we have the time interval constant set to
RTC.alarm(ALARM_1); // clear the alarm flag
RTC.squareWave(SQWAVE_NONE); // configure the INT/SQW pin for "interrupt" operation (disable square wave output)
RTC.alarmInterrupt(ALARM_1, true); // enable interrupt output for Alarm 1
}
void loop() {
delay(5000);//wait 5 seconds before going to sleep. When in a project, we would it is best to make this short as possible
sleepNow(); // run the sleepNow function
}
void sleepNow() {
sleep_enable();//Enabling sleep mode
attachInterrupt(0, wakeUpNow, LOW);//attaching a interrupt to pin d2
set_sleep_mode(SLEEP_MODE_PWR_DOWN);//Setting the sleep mode, in our case full sleep
digitalWrite(ledPin, LOW); //turning LED off
time_t t;// creates temporary time variable
t = RTC.get(); //gets current time from RTC
Serial.println("Sleep Time: " + String(hour(t)) + ":" + String(minute(t)) + ":" + String(second(t))); //prints time stamp on serial monitor
delay(1000); //wait one second to allow the LED to be turned off before going to sleep
sleep_cpu();//heres where the Arduino is actually put to sleep
Serial.println("just woke up!");//next line of code executed after the interrupt
digitalWrite(ledPin, HIGH); //turns the LED on
t = RTC.get();//get the new time from the RTC
Serial.println("WakeUp Time: " + String(hour(t)) + ":" + String(minute(t)) + ":" + String(second(t))); //Prints time stamp
getTempAndSoil(); //Run the TempAndSoil function
//Set New Alarm
int alarmTime = 0; //temporary variable to store the new alarm time in minutes
//the next few lines are to roll the alarm over when it gets near the next hour
if (minute(t) <= (60-time_interval))
{
alarmTime = minute(t) + time_interval;
}
else
{
alarmTime = (minute(t) + time_interval) - 60;
}
RTC.setAlarm(ALM1_MATCH_MINUTES , 0, alarmTime, 0, 0); // set new alarm
// The next few lines of code I use for troubleshooting. This way I can make sure the clock is waking up at the correct time
Serial.print("The next alarm will go off at: ");
//These lines are to print the correct hour that the next alarm will go off
if ((minute(t) <= 60-time_interval) && (hour(t) <= 22))
{
Serial.print(hour(t));
}
else if ((minute(t) >= 60-time_interval) && (hour(t) <= 22))
{
Serial.print(hour(t) + 1);
}
else
{
Serial.print(0);
}
Serial.print(":"); // print a colon symbol
//print the correct minute, including leading zero if less than 10
if (alarmTime <= 9)
{
Serial.print("0");
}
Serial.println(alarmTime);
//Last thing we do is clear the alarm flag
RTC.alarm(ALARM_1);
}
void wakeUpNow() //This is the code that happens when the interrupt is activated
{
Serial.println("Interrrupt Fired");//Print message to serial monitor
sleep_disable();//Disable sleep mode
detachInterrupt(0); //Removes the interrupt from pin 2;
}
void getTempAndSoil()
{
float temperatureC = 0, tempF = 0; //set up float variable to store Celsius and Fahrenheit temp
temperatureC = mpl115a2.getTemperature(); //get temperature from the sensor
tempF = (temperatureC * 1.8) + 32; //convert the temperature from Celsius to Fahrenheit.
Serial.print("Temp (*F): "); Serial.print(tempF, 1); Serial.println(" *F"); //Print the temperature to the Serial Monitor
Serial.print("Soil Moisture = ");
//get soil moisture value from the function below and print it
Serial.println(readSoil());
addWater(); // Run the add water function
}
int readSoil()
{
digitalWrite(soilPower, HIGH);//turn the soil moisture sensor on
delay(10);//wait 10 milliseconds
moistureVal = analogRead(soilPin);//Read the value from sensor
digitalWrite(soilPower, LOW);//turn the soil moisture sensor off
return moistureVal;//send current moisture value
}
void addWater()
{
if (moistureVal <= 100) //If the soil moisture gets too low (The value will need to be set to accompany the soil that you are using)
{
//This is where you could change the code to run a relay, or run a water pump to water your plant. I just flashed a LED as an example to show that the plant would need to be watered.
for (int num = 0; num <= 10; num++)
{
digitalWrite(pumpLED, HIGH);
delay(1000);
digitalWrite(pumpLED, LOW);
delay(1000);
Serial.print("PUMP ON");
Serial.println(num);
}
}
}
RTC 和感測器接線圖
鏈結接到 Scheme-It 原理圖： https://www.digikey.com/schemeit/project/arduino-uno-rtc-and-sensors-sleep-0FCQKUG4006G/
