本次实验我使用的是购买的一个DS1307 RTC模块,上面集成了一个DS18B20温度传感器,还集成了另外一个存储芯片~~
先上图
再看下硬件连接图,DS1307是I2C接口SCL接模拟5号口,SDA接模拟4号口。DS18B20是单总线模式,他的DS接口接数字2号口。
DS18B20:
DS18x20系列数字温度传感器主要有DS18S20和DS18B20(DS18S20只有9位一种工作模式,分辨率只到0.5摄氏度,DS18B20有9、10、11、12位四种工作可编程控制的模式,分辨率最高为0.0625摄氏度。),都是由美国Dallas半导体公司(现在改名叫Maxim)生产的。这个系列最大的特点就是采用了Maxim的专利技术1-Wire。顾名思义,1-Wire就是采用单一信号线,但可像I2C,SPI一样,同时传输时钟(clock)又传输数据(data),而且数据传输是双向的。1-Wire 使用较低的数据传输速率,通常是用来沟通小型device,如数位温度计。通过1-Wire技术可以在单一信号线的基础上构成传感器网络,Maxim起名”MicroLan”。
DS18x20的供电主要有两种模式:
Parasite power mode/寄生供电
所谓的寄生供电是指DS18x20只需要两根接线,一根数据线,一根接地线,数据线上还要接一个4.7k上拉电阻连电源,数据线同时也提供了电能。DS18x20内置了电容,高电平期时把电能储存在内部电容里,低电平期内消耗内部电容里的能量工作,直到下次高电平期内再次电容充电。虽然这样的模式简化了线路同时也带来了一些缺陷:
1. 电路的电流一般很小,只有当DS18x20进行温度转化或者写EEPROM时会高达1.5mA,当DS18x20进行上述操作时,数据线必须保持电平拉高状态直到操作结束,期间master端的Arduino不能做任何操作,DS18x20温度转化时这个时间间隔大概是750ms。
2.如果要求DS18x20有精确的转化,数据线在温度转化期间必须保证足够的能量,但当你使用多个DS18x20构成MicroLan进行多点测温时,单靠4.7k的上拉电阻无法提供足够的能量,会导致较大的测温误差。
Normal (external supply) mode/标准(外部供电)
标准外部供电模式,相比寄生供电模式,每个DS18x20需要多一条独立的电源线接独立电源。虽然多用些线,但由于外部供电,保证了每个设备的进精确度和稳定性。而且没有了上述温度转换期间Arduino不能做任何事的问题。
DS18B20的详细介绍就不多讲了,具体可以查看论坛的另一篇帖子http://www.geek-workshop.com/for ... =198&extra=page%3D1
直接进入实战,调用DS18B20,需要使用OneWire库。
把下面代码下载进入arduino控制板。ARDUINO 代码复制打印
- #include h>
- // DS18S20 Temperature chip i/o
- OneWire ds(2); // on pin 2
- void setup(void) {
- // initialize inputs/outputs
- // start serial port
- Serial.begin(9600);
- }
- void loop(void) {
- byte i;
- byte present = 0;
- byte data[12;
- byte addr[8;
- if ( !ds.search(addr)) {
- Serial.print("No more addresses.n");
- ds.reset_search();
- return;
- }
- Serial.print("R=");
- for( i = 0; i < 8; i++) {
- Serial.print(addr[i, HEX);
- Serial.print(" ");
- }
- if ( OneWire::crc8( addr, 7) != addr[7) {
- Serial.print("CRC is not valid!n");
- return;
- }
- if ( addr[0 == 0x10) {
- Serial.print("Device is a DS18S20 family device.n");
- }
- else if ( addr[0 == 0x28) {
- Serial.print("Device is a DS18B20 family device.n");
- }
- else {
- Serial.print("Device family is not recognized: 0x");
- Serial.println(addr[0,HEX);
- return;
- }
- ds.reset();
- ds.select(addr);
- ds.write(0x44,1); // start conversion, with parasite power on at the end
- delay(1000); // maybe 750ms is enough, maybe not
- // we might do a ds.depower() here, but the reset will take care of it.
- present = ds.reset();
- ds.select(addr);
- ds.write(0xBE); // Read Scratchpad
- Serial.print("P=");
- Serial.print(present,HEX);
- Serial.print(" ");
- for ( i = 0; i < 9; i++) { // we need 9 bytes
- data[i = ds.read();
- Serial.print(data[i, HEX);
- Serial.print(" ");
- }
- Serial.print(" CRC=");
- Serial.print( OneWire::crc8( data, 8), HEX);
- Serial.println();
- }
代码下载好以后打开串口编辑器,然后就会出现下面这样子的画面。
虽然我们读到了Scratchpad的数据,但是显示的是HEX16进制代码,我们还需要转化成我们能读的温度格式。这里推荐一个叫Dallas Temperature Control的Library,大大简化了这个过程。官方地址:http://www.mile***urton.com/?titl ... ure_Control_LibraryARDUINO 代码复制打印
- #include h>
- #include h>
- // Data wire is plugged into port 2 on the Arduino
- #define ONE_WIRE_BUS 2
- // Setup a oneWire instance to communicate with any OneWire devices (not just Maxim/Dallas temperature ICs)
- OneWire oneWire(ONE_WIRE_BUS);
- // Pass our oneWire reference to Dallas Temperature.
- DallasTemperature sensors(&oneWire);
- void setup(void)
- {
- // start serial port
- Serial.begin(9600);
- Serial.println("Dallas Temperature IC Control Library Demo");
- // Start up the library
- sensors.begin();
- }
- void loop(void)
- {
- // call sensors.requestTemperatures() to issue a global temperature
- // request to all devices on the bus
- Serial.print("Requesting temperatures...");
- sensors.requestTemperatures(); // Send the command to get temperatures
- Serial.println("DONE");
- Serial.print("Temperature for the device 1 (index 0) is: ");
- Serial.println(sensors.getTemPCByIndex(0));
- }
代码下载好以后,打开串口监视器,就可以看到当前室温了。
下面我们试用一下DS1307时钟芯片功能。
先把下面库自带测试代码下载进入arduino控制板ARDUINO 代码复制打印
- #include h>
- #include h>
- #include h>
- int rtc[7;
- int ledPin = 13;
- void setup()
- {
- DDRC|=_BV(2) |_BV(3); // POWER:Vcc Gnd
- PORTC |=_BV(3); // VCC PINC3
- pinMode(ledPin, OUTPUT);
- Serial.begin(9600);
- RTC.stop();
- RTC.set(DS1307_SEC,1);
- RTC.set(DS1307_MIN,57);
- RTC.set(DS1307_HR,17);
- RTC.set(DS1307_DOW,2);
- RTC.set(DS1307_DATE,18);
- RTC.set(DS1307_MTH,1);
- RTC.set(DS1307_YR,10);
- RTC.start();
- }
- void loop()
- {
- RTC.get(rtc,true);
- for(int i=0; i<7; i++)
- {
- Serial.print(rtc[i);
- Serial.print(" ");
- }
- Serial.println();
- digitalWrite(ledPin, HIGH);
- delay(500);
- digitalWrite(ledPin, LOW);
- delay(500);
- }
然后打开串口监视器,就能看到类似下图的样子。
这个模块上还有一个T24C32A EEPROM存储器。。。下面上一个全面一点的代码,对各个期间进行测试。其中刚开始会对I2C器件进行扫描。。。代码不错,大家可以参考下。ARDUINO 代码复制打印
- /**
- * I2CScanner.pde -- I2C bus scanner for Arduino
- *
- * 2009, Tod E. Kurt, http://todbot.com/blog/
- *
- */
- #include h>
- #include "Wire.h"
- #include h>
- #include h>
- #include h>
- extern "C" {
- #include "utility/twi.h" // from Wire library, so we can do bus scanning
- }
- byte start_address = 1;
- byte end_address = 127;
- OneWire ds(2); // on pin 2
- byte Tdata[12;
- int sensorValue = 0; // value read from the pot
- int rtc[7;
- float TT=0.0;
- // Scan the I2C bus between addresses from_addr and to_addr.
- // On each address, call the callback function with the address and result.
- // If result==0, address was found, otherwise, address wasn't found
- // (can use result to potentially get other status on the I2C bus, see twi.c)
- // Assumes Wire.begin() has already been called
- void scanI2CBus(byte from_addr, byte to_addr,
- void(*callback)(byte address, byte result) )
- {
- byte rc;
- byte data = 0; // not used, just an address to feed to twi_writeTo()
- for( byte addr = from_addr; addr <= to_addr; addr++ ) {
- rc = twi_writeTo(addr, &data, 0, 1);
- if(rc==0) callback( addr, rc );
- }
- }
- // Called when address is found in scanI2CBus()
- // Feel free to change this as needed
- // (like adding I2C comm code to figure out what kind of I2C device is there)
- void scanFunc( byte addr, byte result ) {
- Serial.print("addr: ");
- Serial.print(addr,DEC);
- addr = addr<<1;
- Serial.print("t HEX: 0x");
- Serial.print(addr,HEX);
- Serial.println( (result==0) ? "t found!":" ");
- // Serial.print( (addr%4) ? "t":"n");
- }
- void i2c_eeprom_write_byte( int deviceaddress, unsigned int eeaddress, byte data ) {
- int rdata = data;
- Wire.beginTransmission(deviceaddress);
- Wire.send((int)(eeaddress >> 8)); // MSB
- Wire.send((int)(eeaddress & 0xFF)); // LSB
- Wire.send(rdata);
- Wire.endTransmission();
- }
- // WARNING: address is a page address, 6-bit end will wrap around
- // also, data can be maximum of about 30 bytes, because the Wire library has a buffer of 32 bytes
- void i2c_eeprom_write_page( int deviceaddress, unsigned int eeaddresspage, byte* data, byte length ) {
- Wire.beginTransmission(deviceaddress);
- Wire.send((int)(eeaddresspage >> 8)); // MSB
- Wire.send((int)(eeaddresspage & 0xFF)); // LSB
- byte c;
- for ( c = 0; c < length; c++)
- Wire.send(data[c);
- Wire.endTransmission();
- }
- byte i2c_eeprom_read_byte( int deviceaddress, unsigned int eeaddress ) {
- byte rdata = 0xFF;
- Wire.beginTransmission(deviceaddress);
- Wire.send((int)(eeaddress >> 8)); // MSB
- Wire.send((int)(eeaddress & 0xFF)); // LSB
- Wire.endTransmission();
- Wire.requestFrom(deviceaddress,1);
- if (Wire.available()) rdata = Wire.receive();
- return rdata;
- }
- // maybe let's not read more than 30 or 32 bytes at a time!
- void i2c_eeprom_read_buffer( int deviceaddress, unsigned int eeaddress, byte *buffer, int length ) {
- Wire.beginTransmission(deviceaddress);
- Wire.send((int)(eeaddress >> 8)); // MSB
- Wire.send((int)(eeaddress & 0xFF)); // LSB
- Wire.endTransmission();
- Wire.requestFrom(deviceaddress,length);
- int c = 0;
- for ( c = 0; c < length; c++ )
- if (Wire.available()) buffer[c = Wire.receive();
- }
- void DS1302_SetOut(byte data ) {
- Wire.beginTransmission(B1101000);
- Wire.send(7); // LSB
- Wire.send(data);
- Wire.endTransmission();
- }
- byte DS1302_GetOut(void) {
- byte rdata = 0xFF;
- Wire.beginTransmission(B1101000);
- Wire.send(7); // LSB
- Wire.endTransmission();
- Wire.requestFrom(B1101000,1);
- if (Wire.available()) {
- rdata = Wire.receive();
- Serial.println(rdata,HEX);
- }
- return rdata;
- }
- void showtime(void){
- byte i;
- Serial.print("Time=");
- DS1302_SetOut(0x00);
- RTC.get(rtc,true);
- for(int i=0; i<7; i++) {
- Serial.print(rtc[i);
- Serial.print(" ");
- }
- }
- void readBatVcc(void){
- sensorValue = analogRead(A1);
- TT = sensorValue*0.0047;
- Serial.print("Battery: ");
- Serial.print(TT);
- Serial.print("V");
- }
- // standard Arduino setup()
- void setup()
- {
- DDRC|=_BV(2) |_BV(3);
- PORTC |=_BV(3);
- Wire.begin();
- Serial.begin(19200);
- Serial.println("--- I2C Bus Scanner Test---");
- Serial.print("starting scanning of I2C bus from ");
- Serial.print(start_address,DEC);
- Serial.print(" to ");
- Serial.print(end_address,DEC);
- Serial.println("...");
- // start the scan, will call "scanFunc()" on result from each address
- scanI2CBus( start_address, end_address, scanFunc );
- Serial.println("n");
- Serial.println("--- EEPROM Test---");
- char somedata[ = "this is data from the eeprom"; // data to write
- i2c_eeprom_write_page(0x50, 0, (byte *)somedata, sizeof(somedata)); // write to EEPROM
- delay(100); //add a small delay
- Serial.println("Written Done");
- delay(10);
- Serial.print("Read EERPOM:");
- byte b = i2c_eeprom_read_byte(0x50, 0); // access the first address from the memory
- int addr=0; //first address
- while (b!=0)
- {
- Serial.print((char)b); //print content to serial port
- addr++; //increase address
- b = i2c_eeprom_read_byte(0x50, addr); //access an address from the memory
- }
- Serial.println("n");
- Serial.println("");
- Serial.println("--- DS11307 RTC Test---");
- showtime();
- if(rtc[6<2011){
- RTC.stop();
- RTC.set(DS1307_SEC,1);
- RTC.set(DS1307_MIN,52);
- RTC.set(DS1307_HR,16);
- RTC.set(DS1307_DOW,2);
- RTC.set(DS1307_DATE,25);
- RTC.set(DS1307_MTH,1);
- RTC.set(DS1307_YR,11);
- RTC.start();
- Serial.println("SetTime:");
- showtime();
- }
- Serial.println("nn");
- Serial.println("--- Reserve Power Test---");
- Serial.println(" Close POWER!:");
- PORTC &=~_BV(3);
- byte time;
- for(time=0;time<5;time++){
- digitalWrite(13,HIGH);
- delay(500);
- digitalWrite(13,LOW);
- delay(500);
- readBatVcc();
- Serial.println("");
- }
- PORTC |=_BV(3);
- Serial.println("n POWER On!");
- delay(500);
- showtime();
- Serial.println("n");
- Serial.println("=== Done ===");
- Serial.println("n");
- }
- // standard Arduino loop()
- void loop()
- {
- byte i;
- byte present = 0;
- unsigned int Temper=0;
- readBatVcc();
- ds.reset();
- ds.write(0xCC,1);
- ds.write(0x44,1); // start conversion, with parasite power on at the end
- digitalWrite(13,HIGH);
- delay(450);
- digitalWrite(13,LOW);
- delay(450);
- present = ds.reset();
- ds.write(0xCC,1);
- ds.write(0xBE); // Read Scratchpad
- for ( i = 0; i < 9; i++) { // we need 9 bytes
- Tdata[i = ds.read();
- }
- Temper = (Tdata[1<<8 | Tdata[0);
- TT =Temper*0.0625;
- if(TT>200){
- Serial.println("t DS18B20 Not installed!");
- }else{
- Serial.print("t Temperature=");
- Serial.println(TT);
- }
- Serial.println("");
- }
然后打开串口监视器,波特率要调节为19200.
附件是这次需要用到的库(适用于0022与0023 IDE):
OneWire.rar (8.59 KB, 下载次数: 430)
DS1307.rar (2.59 KB, 下载次数: 645)
DallasTemperature_371Beta.zip (22.44 KB, 下载次数: 392)
补充1.0.1下可用的DS180B20库
OneWire_1.0.1.zip (14.38 KB, 下载次数: 691)
DallasTemperature_372Beta_1.0.1.zip (22.87 KB, 下载次数: 648)
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