In articolul anterior, Noii senzori de temperatura MAX31820 fata de "clasicii" DS18B20, am conectat in paralel un senzor DS18B20 (cu precize garantata de +0,50C pe domeniul de la -10 la +850C, in rest e de +20C) si 2 de tipul MAX31820 (care este o varianta noua, cu precize garantata de +0,50C doar pe un domeniu de +10...+450 Celsius, in rest e de +20C).
Schema de conectare este simpla:
Deoarece sunt din aceeasi clasa, ele sunt indentificate de Arduino ca fiind DS18B20.
In articolul Arduino 1-Wire Address Finder este prezentat un sketch, care gaseste adresele tuturor senzorilor pe comunicatia 1-Wire. L-am incarcat si eu si am obtinut:
Sketch-ul, in care doar am pus pinul de date la 10, cum aveam eu facut, este:
// 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>
OneWire ds(10); // Connect your 1-wire device to pin 10
void setup(void) {
Serial.begin(9600);
discoverOneWireDevices();
}
void discoverOneWireDevices(void) {
byte i;
byte present = 0;
byte data[12];
byte addr[8];
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[i] < 16) {
Serial.print('0');
}
Serial.print(addr[i], HEX);
if (i < 7) {
Serial.print(", ");
}
}
if ( OneWire::crc8( addr, 7) != addr[7]) {
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
}
Deoarece trebuie sa le identific cumva, m-am inspirat din articolul Two DS18B20 Temp Sensors on LCD Display! in care apare si o librarie numita DallasTemperature Arduino Library, care se gaseste tot in articolul mentionat la inceput, Arduino 1-Wire Address Finder.
Dupa descarcarea librariei, dezarhivarea si mutarea in subdirectorul de librarii al programului Arduino, am ales exemplul numit Multiple:
si l-am modificat pentru cazul meu, cu 3 senzori, in dreapta e DS18B20, iar ceilalti 2 senzori MAX31820 sunt in mijloc, respectiv stanga.
#include <OneWire.h>
#include <DallasTemperature.h>
// Data wire is plugged into port 10 on the Arduino
#define ONE_WIRE_BUS 10
#define TEMPERATURE_PRECISION 12
// 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);
// arrays to hold device addresses
DeviceAddress rightThermometer, midleThermometer, leftThermometer;
void setup(void)
{
// start serial port
Serial.begin(9600);
Serial.println("Dallas Temperature IC Control Library Demo");
// Start up the library
sensors.begin();
// locate devices on the bus
Serial.print("Locating devices...");
Serial.print("Found ");
Serial.print(sensors.getDeviceCount(), DEC);
Serial.println(" devices.");
// report parasite power requirements
Serial.print("Parasite power is: ");
if (sensors.isParasitePowerMode()) Serial.println("ON");
else Serial.println("OFF");
// assign address manually. the addresses below will beed to be changed
// to valid device addresses on your bus. device address can be retrieved
// by using either oneWire.search(deviceAddress) or individually via
// sensors.getAddress(deviceAddress, index)
//insideThermometer = { 0x28, 0x1D, 0x39, 0x31, 0x2, 0x0, 0x0, 0xF0 };
//outsideThermometer = { 0x28, 0x3F, 0x1C, 0x31, 0x2, 0x0, 0x0, 0x2 };
// search for devices on the bus and assign based on an index. ideally,
// you would do this to initially discover addresses on the bus and then
// use those addresses and manually assign them (see above) once you know
// the devices on your bus (and assuming they don't change).
//
// method 1: by index
if (!sensors.getAddress(rightThermometer, 0)) Serial.println("Unable to find address for Device 0");
if (!sensors.getAddress(midleThermometer, 1)) Serial.println("Unable to find address for Device 1");
if (!sensors.getAddress(leftThermometer, 2)) Serial.println("Unable to find address for Device 2");
// method 2: search()
// search() looks for the next device. Returns 1 if a new address has been
// returned. A zero might mean that the bus is shorted, there are no devices,
// or you have already retrieved all of them. It might be a good idea to
// check the CRC to make sure you didn't get garbage. The order is
// deterministic. You will always get the same devices in the same order
//
// Must be called before search()
//oneWire.reset_search();
// assigns the first address found to insideThermometer
//if (!oneWire.search(insideThermometer)) Serial.println("Unable to find address for insideThermometer");
// assigns the seconds address found to outsideThermometer
//if (!oneWire.search(outsideThermometer)) Serial.println("Unable to find address for outsideThermometer");
// show the addresses we found on the bus
Serial.print("Device 0 Address: ");
printAddress(rightThermometer);
Serial.println();
Serial.print("Device 1 Address: ");
printAddress(midleThermometer);
Serial.println();
Serial.print("Device 2 Address: ");
printAddress(leftThermometer);
Serial.println();
// set the resolution to 9..12 bit
sensors.setResolution(rightThermometer, TEMPERATURE_PRECISION);
sensors.setResolution(midleThermometer, TEMPERATURE_PRECISION);
sensors.setResolution(leftThermometer, TEMPERATURE_PRECISION);
Serial.print("Device 0 Resolution: ");
Serial.print(sensors.getResolution(rightThermometer), DEC);
Serial.println();
Serial.print("Device 1 Resolution: ");
Serial.print(sensors.getResolution(midleThermometer), DEC);
Serial.println();
Serial.print("Device 2 Resolution: ");
Serial.print(sensors.getResolution(leftThermometer), DEC);
Serial.println();
}
// function to print a device address
void printAddress(DeviceAddress deviceAddress)
{
for (uint8_t i = 0; i < 8; i++)
{
// zero pad the address if necessary
if (deviceAddress[i] < 16) Serial.print("0");
Serial.print(deviceAddress[i], HEX);
}
}
// function to print the temperature for a device
void printTemperature(DeviceAddress deviceAddress)
{
float tempC = sensors.getTempC(deviceAddress);
Serial.print("Temp C: ");
Serial.print(tempC);
Serial.print(" Temp F: ");
Serial.print(DallasTemperature::toFahrenheit(tempC));
}
// function to print a device's resolution
void printResolution(DeviceAddress deviceAddress)
{
Serial.print("Resolution: ");
Serial.print(sensors.getResolution(deviceAddress));
Serial.println();
}
// main function to print information about a device
void printData(DeviceAddress deviceAddress)
{
Serial.print("Device Address: ");
printAddress(deviceAddress);
Serial.print(" ");
printTemperature(deviceAddress);
Serial.println();
}
void loop(void)
{
// call sensors.requestTemperatures() to issue a global temperature
// request to all devices on the bus
Serial.print("Requesting temperatures...");
sensors.requestTemperatures();
Serial.println("DONE");
// print the device information
printData(rightThermometer);
printData(midleThermometer);
printData(leftThermometer);
delay(3000);
}
Pe ecranul de monitorizare seriala am acum datele:
cu minime modificari:
12.ian.2014
M-a gandit sa nu las neterminata treaba, asa ca m-am mai jucat cu sketch-ul si pe ecram am obtinut:
iar sketch-ul folosit este:
#include <OneWire.h>
#include <DallasTemperature.h>
// Data wire is plugged into port 10 on the Arduino
#define ONE_WIRE_BUS 10
#define TEMPERATURE_PRECISION 12
// 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);
// arrays to hold device addresses
DeviceAddress rightThermometer, midleThermometer, leftThermometer;
void setup(void)
{
// start serial port
Serial.begin(9600);
Serial.println("Dallas Temperature IC Control Library use by niq_ro");
Serial.println("---------------------------------------------------");
// Start up the library
sensors.begin();
DeviceAddress rightThermometer = { 0x28, 0xAC, 0x7A, 0xD4, 0x4, 0x0, 0x0, 0x7E };
DeviceAddress midleThermometer = { 0x28, 0xF5, 0xFB, 0x58, 0x5, 0x0, 0x0, 0xA0 };
DeviceAddress leftThermometer = { 0x28, 0xCB, 0xF0, 0x58, 0x5, 0x0, 0x0, 0x2E };
// method 1: by index
if (!sensors.getAddress(rightThermometer, 0)) Serial.println("Unable to find address for Device 0");
if (!sensors.getAddress(midleThermometer, 1)) Serial.println("Unable to find address for Device 1");
if (!sensors.getAddress(leftThermometer, 2)) Serial.println("Unable to find address for Device 2");
// show the addresses we found on the bus
Serial.print("Device 0 Address: ");
printAddress(rightThermometer);
Serial.println();
Serial.print("Device 1 Address: ");
printAddress(midleThermometer);
Serial.println();
Serial.print("Device 2 Address: ");
printAddress(leftThermometer);
Serial.println();
// set the resolution to 9..12 bit
sensors.setResolution(rightThermometer, TEMPERATURE_PRECISION);
sensors.setResolution(midleThermometer, TEMPERATURE_PRECISION);
sensors.setResolution(leftThermometer, TEMPERATURE_PRECISION);
/*
Serial.print("Device 0 Resolution: ");
Serial.print(sensors.getResolution(rightThermometer), DEC);
Serial.println();
Serial.print("Device 1 Resolution: ");
Serial.print(sensors.getResolution(midleThermometer), DEC);
Serial.println();
Serial.print("Device 2 Resolution: ");
Serial.print(sensors.getResolution(leftThermometer), DEC);
Serial.println();
*/
}
// function to print a device address
void printAddress(DeviceAddress device)
{
for (uint8_t i = 0; i < 8; i++)
{
// zero pad the address if necessary
if (device[i] < 16) Serial.print("0");
Serial.print(device[i], HEX);
}
Serial.println(" - ");
}
// function to print the temperature for a device
void printTemperature(DeviceAddress device)
{
float tempC = sensors.getTempC(device);
Serial.print("Temp C: ");
if (tempC == -127.00) {
Serial.print("Error");
} else {
Serial.print(tempC);
Serial.print(" Temp F: ");
Serial.print(DallasTemperature::toFahrenheit(tempC));
}
}
// function to print a device's resolution
void printResolution(DeviceAddress device)
{
Serial.print("Resolution: ");
Serial.print(sensors.getResolution(device));
Serial.println();
}
// main function to print information about a device
void printData(DeviceAddress device)
{
Serial.print("Address: ");
printAddress(device);
Serial.print(" ");
printTemperature(device);
Serial.println();
}
void loop(void)
{
DeviceAddress rightThermometer = { 0x28, 0xAC, 0x7A, 0xD4, 0x4, 0x0, 0x0, 0x7E };
DeviceAddress midleThermometer = { 0x28, 0xF5, 0xFB, 0x58, 0x5, 0x0, 0x0, 0xA0 };
DeviceAddress leftThermometer = { 0x28, 0xCB, 0xF0, 0x58, 0x5, 0x0, 0x0, 0x2E };
// call sensors.requestTemperatures() to issue a global temperature
// request to all devices on the bus
Serial.println("---------------------------------------");
Serial.println(" ");
Serial.print("Requesting temperatures...");
sensors.requestTemperatures();
Serial.println("DONE");
Serial.println("---------------------------------------");
Serial.println(" ");
// print the device information
Serial.print("Device DS18B20 (right) ");
printData(rightThermometer);
Serial.println("---------------------------------------");
Serial.print("Device MAX31820 (center) ");
printData(midleThermometer);
Serial.println("---------------------------------------");
Serial.print("Device MAX31820 (left) ");
printData(leftThermometer);
Serial.println("---------------------------------------");
delay(3000);
}
17.01.2014
PS: Dupa cum am mentionat si la finalul articolului anterior (Noii senzori de temperatura MAX31820 fata de "clasicii" DS18B20), in datasheet-ul senzorilor MAX31820, se mentioneaza ca tensiunea de alimentare normala este intre 3 si 3,7V deci ar functiona perfect cu microcontroler-e alimentate la tensiunea de 3,3V. Tot in datasheet se mentioneaza ca tensiunea maxima admisa este de 6V, exact ca la DS18B20... Eu le-am alimentat la 5V, cat era la Arduino si au mers perfect.
