Here's the first shot of what is to become a temperature controlled refrigerator.
(obviously I'm missing the refrigerator, but I've tested it on a small peltier box)
I'm using a Diecimila board with a Maxim DS18B20 temperature sensor & Matrix Orbital LK204-25-PC LCD. I plan on switching a large relay to control the minifridge in a similar fashion to previous implementations (Arduino Beer Thermostat – uCHobby). The final product will also include a Java app that interfaces the Diecimila with rrdtool on a webserver.
Let me know if anyone wants code - I should publish everything when I'm finished as well.
I'm just starting to play with electronics at all and so I got the Arduino Diecimila board and now just want to play around with it. I also purchase some DS18B20 temperature sensors from Maxim and want to know how they work.
#include <OneWire.h>
OneWire ds(10); // on pin 10
long temperature = 0;
int Fract = 0;
int Whole = 0;
void setup()
{
beginSerial(19200);
}
void loop()
{
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] != 0x28) {
// Serial.print("Device is not a DS18S20 family device.\n");
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("Kegerator Ver. 0.1 ");
Serial.println(" www.swilly.tk");
Serial.print("Temperature: ");
// ACTUAL TEMPERATURE PROCESSING
// NOTE: outputs the temperature as a whole number
// (multiplies the decimal by 10000) - Serial.print won't do decimals
long temperature = (long)((((data[1] << 8 ) | data[0]) * 0.0625) * 10000);
// Formats the output as a decimal
Whole = temperature / 10000;
Fract = temperature % 10000;
Serial.print(Whole);
Serial.print(".");
Serial.print((int)(Fract / 1000)); // rounds to 10th's
Serial.println("C");
}
I'm not sure if it works, because I've adapted a bit from my use. I also know that it is really sloppy, but I plan on going back and implementing some of the features in my Java app. (CRC checking, address selection, etc.) later.
Also, you'll need to change the line:
if ( addr[0] != 0x10) {
to:
if ( addr[0] != 0x28) {
if you're strictly going from the example.
I had originally typed up a more thorough explanation, but Firefox crashed on me and lost everything
If you're a bit more technical, you may want to check this out as well: http://www.maxim-ic.com.cn/pdfserv/en/ds/DS18B20.pdf. It helped me understand how the actual temperature conversion from the raw sensor values to Celsius was being performed.
Let me know if you need anything explained more in-depth... I was a bit more hasty in the second version of the post.
I've been fooling around a bit with data collection lately, and have created this: http://swilly.tk:20001/kegerator/kegerator.php
The blue line is the temperature, and orange is the compressor status.
It's a php generated svg (firefox, safari, ... basically only ie doesn't support it). It will eventually be accompanied by some javascript which dynamically polls an api and re-draws the image accordingly.
I'll probably get around to finishing up the lcd and everything in a few weeks when exams are over. More pics to come.
- I should publish everything when I'm finished as well.