如何在arduino上扩展多个DS18B20温度传感器？
本帖最后由 lauren 于 2014-6-30 17:03 编辑问题如题，经过网上的一些调研，找到了一些结果，能够直接通过arduino驱动多个18B20温度探头。硬件连接就是多个探头共享使用同一个上拉电阻，并且通过一些样例程序扫描多个探头的单总线地址，更新到样例软件里面即可驱动。
单总线是个相当暴力的东西，硬件端口资源占用少，而18B20经过一些伙伴的帖子评测，也证实是温度传感器中的战斗机。样例程序如下，和大家分享下哈。
关于单总线设备地址的扫描程序，如样例程序的备注，在：http://www.hacktronics.com/Tutorials/arduino-1-wire-address-finder.html 可以找到哈。
样例中包含了LCD显示的程序，所以使用时可以忽略或者在开发自己程序的时候删掉哈。
/* YourDuino.com Example: Multiple DS18B20 Temperature Sensors
Displayed on 4x20 character LCD display
DS18B20 Pinout (Left to Right, pins down, flat side toward you)
- Left = Ground
- Center = Signal (Pin 10):(with 3.3K to 4.7K resistor to +5 or 3.3 )
- Right= +5 or +3.3 V
terry@yourduino.com */
/*-----( Import needed libraries )-----*/
// Get 1-wire Library here: http://www.pjrc.com/teensy/td_libs_OneWire.html
#include <OneWire.h>
//Get DallasTemperature Library here:http://milesburton.com/Main_Page?title=Dallas_Temperature_Control_Library
#include <DallasTemperature.h>
// Wire (I2C) Library
#include <Wire.h>
// LCD Library
#include <LCD.h>
#include <LiquidCrystal_I2C.h>// F Malpartida's NewLiquidCrystal library
//Download: https://bitbucket.org/fmalpartida/new-liquidcrystal/downloads
// Move original LiquidCrystal library elsewhere, copy this in it's place
/*-----( Declare Constants and Pin Numbers )-----*/
// Data wire is plugged into port 10 on the Arduino (can be changed)
#define ONE_WIRE_BUS 10 // NOTE: No ";" on #define
#define I2C_ADDR 0x20// Define I2C Address for the PCF8574A
//---(Following are the PCF8574 pin assignments to LCD connections )----
// This are different than earlier/different I2C LCD displays
#define BACKLIGHT_PIN7
#define En_pin4
#define Rw_pin5
#define Rs_pin6
#define D4_pin0
#define D5_pin1
#define D6_pin2
#define D7_pin3
#defineLED_OFF0
#defineLED_ON1
/*-----( Declare objects )-----*/
// Setup a oneWire instance to communicate with any OneWire devices
// (not just Maxim/Dallas temperature ICs)
OneWire oneWire(ONE_WIRE_BUS);
// Pass address of our oneWire instance to Dallas Temperature.
DallasTemperature sensors(&oneWire);
// Start the LCD display library
LiquidCrystal_I2Clcd(I2C_ADDR,En_pin,Rw_pin,Rs_pin,D4_pin,D5_pin,D6_pin,D7_pin);
/*-----( Declare Variables )-----*/
// Assign the addresses of your 1-Wire temp sensors.
// See the tutorial on how to obtain these addresses:
// http://www.hacktronics.com/Tutorials/arduino-1-wire-address-finder.html
// WP 1
DeviceAddress Probe01 = { 0x28, 0x9A, 0x80, 0x40, 0x04, 0x00, 0x00, 0xD5 }; // "4"
DeviceAddress Probe02 = { 0x28, 0xE1, 0xC7, 0x40, 0x04, 0x00, 0x00, 0x0D }; // "5"
DeviceAddress Probe03 = { 0x28, 0x9A, 0x80, 0x40, 0x04, 0x00, 0x00, 0xD5 }; // "4" Again for test
DeviceAddress Probe04 = { 0x28, 0x10, 0xA4, 0x57, 0x04, 0x00, 0x00, 0xA9 };
void setup() /****** SETUP: RUNS ONCE ******/
{
//------- Initialize the Temperature measurement library--------------
sensors.begin();
// set the resolution to 10 bit (Can be 9 to 12 bits .. lower is faster)
sensors.setResolution(Probe01, 10);
sensors.setResolution(Probe02, 10);
sensors.setResolution(Probe03, 10);
sensors.setResolution(Probe04, 10);
//---------------- Initialize the lcd ------------------
lcd.begin (20,4);// 20 characters, 4 lines
// Switch on the backlight
lcd.setBacklightPin(BACKLIGHT_PIN,NEGATIVE);
lcd.setBacklight(LED_ON);
}//--(end setup )---
void loop() /****** LOOP: RUNS CONSTANTLY ******/
{
sensors.requestTemperatures(); // Send the command to get temperatures
lcd.clear();// Reset the display
lcd.home();
lcd.backlight();//Backlight ON if under program control
// Print our characters on the LCD
// NOTE: Line number and character number start at 0 not 1
lcd.setCursor(0,0); //Start at character 0 on line 0
lcd.print("1: ");
displayTemperature(Probe01);
lcd.setCursor(0,1); //Start at character 0 on line 1
lcd.print("2: ");
displayTemperature(Probe02);
lcd.setCursor(0,2); //Start at character 0 on line 2
lcd.print("3: ");
displayTemperature(Probe03);
lcd.setCursor(0,3); //Start at character 0 on line 3
lcd.print("4: ");
displayTemperature(Probe04);
delay(2000);
}//--(end main loop )---
/*-----( Declare User-written Functions )-----*/
void displayTemperature(DeviceAddress deviceAddress)
{
float tempC = sensors.getTempC(deviceAddress);
if (tempC == -127.00) // Measurement failed or no device found
{
lcd.print("Temperature Error");
}
else
{
lcd.print("C=");
lcd.print(tempC);
lcd.print(" F=");
lcd.print(DallasTemperature::toFahrenheit(tempC)); // Convert to F
}
}// End printTemperature
//*********( THE END )***********
同时附上单总线设备地址扫描样例程序哈。
// This sketch looks for 1-wire devices and
// prints their addresses (serial number) to
// the UART, in a format that is useful in Arduino sketches
// Tutorial:
// http://www.hacktronics.com/Tutorials/arduino-1-wire-address-finder.html
#include <OneWire.h>
OneWireds(3);// Connect your 1-wire device to pin 3
void setup(void) {
Serial.begin(9600);
discoverOneWireDevices();
}
void discoverOneWireDevices(void) {
byte i;
byte present = 0;
byte data;
byte addr;
Serial.print("Looking for 1-Wire devices...\n\r");
while(ds.search(addr)) {
Serial.print("\n\rFound \'1-Wire\' device with address:\n\r");
for( i = 0; i < 8; i++) {
Serial.print("0x");
if (addr < 16) {
Serial.print('0');
}
Serial.print(addr, HEX);
if (i < 7) {
Serial.print(", ");
}
}
if ( OneWire::crc8( addr, 7) != addr) {
Serial.print("CRC is not valid!\n");
return;
}
}
Serial.print("\n\r\n\rThat's it.\r\n");
ds.reset_search();
return;
}
void loop(void) {
// nothing to see here
}
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