Msemtd HomeAuto

Michael's Home Instrumentation

• New porch doors have required me to rethink my doorbell!
• We can't hear people knocking on the door
• The people at the door don't know if the old doorbell actually rang
• The old wireless doorbell often didn't ring because the batteries were flat!
• The wireless doorbell didn't require drilling holes in the doorframe - this is a plus
• the 12V battery in the wireless doorbell pushbutton was expensive!

I want to do something simple with the old wireless doorbell and start to develop an extensible home automation/instrumentation project. I have a Nanode and a number of Xinos which I intend to connect on a 4-wire bus around the house.

The old doorbell

Push-button:

• PCB labelled "RL-09 04.04.23"
• Battery 12V A23S "Replaces: 23A, MS21/MN21" A23 on WP cheap 10x pack
• IC1: LP801/V8

Chime unit:

• PCB labelled "RL-09B 04.02.27"
• Batteries 4.5V, 3xAA
• IC2: LP816A

http://www.alldatasheet.com/view.jsp?Searchword=HCF4069UBE

The Nanode - Xino 4-wire Bus

Using a Nanode at my internet gateway router and communicating with and powering multiple slave Xinos on a 4-wire bus...

http://wiki.hackspace.org.uk/wiki/Project:Nanode/Applications#Using_the_Local_Serial_Bus

http://sustburbia.blogspot.com/2010/08/wired-network-for-arduinos.html

Read nanode MAC address: -

https://gist.github.com/1020951#file_nanode_mac.pde

 MAC Address Read Test
 MAC address is 00:04:A3:03:DD:C7

The soil moisture tester

Do these plants need watering?

http://www.instructables.com/id/Garduino-Gardening-Arduino/

Temperature

I have a bag of surplus 47k thermistors (about 500) and I intend to build a number of circuits to measure temperature starting with the very simplest and culminating in a teachable HackSpace project with reasonable accuracy. We will put these devices in fridges, near heat sources, near doors, windows, indoors, outdoors, you name it.

The component:

• Listed in stores as "Future Electronics B4090K Thermistor 47k 5%"
• I think it may be this one
  • http://uk.futureelectronics.com/en/Search.aspx?dsNav=Ny:True,Ro:0,Nea:True,N:477-4294920237
  • http://uk.futureelectronics.com/en/Technologies/Product.aspx?ProductID=NTCLE100E3473JB0VISHAY8666240
• however, the Vishay product may be obsolete and the tolerance is listed as 1.5% rather than 5%

  VISHAY 
   NTCLE100 Series NTC 47 kOhm ±1.5 % Radial Leaded Standard Precision Thermistor
   Mfr Part#:  NTCLE100E3473JB0
   Packaging : BAG 
   Std Packaging Qty: 500
   Min Order Qty: 1
   As low as:  £0.1751  (GBP)
   In Stock:  No
   Type: 
   NTC
   Resistance: 
   47 kO
   Tolerance (%): 
   ±1.5 %
   B-constant: 
   4090 °K
   Temperature Range: 
   -40 to +125 °C

Some Google digging reveals...

• http://www.vishay.com/docs/29049/ntcle100.pdf
• these thermistors are colour coded
  • Yellow Violet Orange Gold
    • B25/85-VALUE = 4090K (+/- 5%) (the gold means 5%)

The simplest circuits and Arduino code...

• http://arduino.cc/playground/Main/InterfacingWithHardware#envtture
  • http://arduino.cc/playground/ComponentLib/Thermistor
  • http://arduino.cc/playground/ComponentLib/Thermistor2
  • http://arduino.cc/playground/ComponentLib/Thermistor3

This is the best code I have found so far - from Thermistor2 but allows us to have our own parameters definition...

 #define NOTTINGHACK_47K 4090.0f,298.15f,47000.0f  // B,T0,R0

#include <math.h>
// enumarating 3 major temperature scales
enum {
  T_KELVIN=0,
  T_CELSIUS,
  T_FAHRENHEIT
};

// manufacturer data for episco k164 10k thermistor
// simply delete this if you don't need it
// or use this idea to define your own thermistors
#define EPISCO_K164_10k 4300.0f,298.15f,10000.0f  // B,T0,R0

// Temperature function outputs float , the actual
// temperature
// Temperature function inputs
// 1.AnalogInputNumber - analog input to read from
// 2.OuputUnit - output in celsius, kelvin or fahrenheit
// 3.Thermistor B parameter - found in datasheet
// 4.Manufacturer T0 parameter - found in datasheet (kelvin)
// 5. Manufacturer R0 parameter - found in datasheet (ohms)
// 6. Your balance resistor resistance in ohms  

float Temperature(int AnalogInputNumber,int OutputUnit,float B,float T0,float R0,float R_Balance)
{
  float R,T;

  R=1024.0f*R_Balance/float(analogRead(AnalogInputNumber)))-R_Balance;
  T=1.0f/(1.0f/T0+(1.0f/B)*log(R/R0));

  switch(OutputUnit) {
    case T_CELSIUS :
      T-=273.15f;
    break;
    case T_FAHRENHEIT :
      T=9.0f*(T-273.15f)/5.0f+32.0f;
    break;
    default:
    break;
  };

  return T;
}
// example of use #1
// reading from analog input 1, using episco k164 definition
// and 10k balance, getting result in celsius

void setup() {
 Serial.begin(9600);
}

void loop() {

 Serial.println("*************************");
 Serial.println("10k Balance");
 Serial.println(Temperature(1,T_CELSIUS,EPISCO_K164_10k,10000.0f));
 Serial.println("*************************");

 delay(500);
}

//example of use #2
// using numbers instead of episco k164 definition
// this time reading from analog input 2
// getting result in fahrenheit

void setup() {
 Serial.begin(9600);
}

void loop() {

 Serial.println("*************************");
 Serial.println("10k Balance");
 Serial.println(Temperature(2,T_FAHRENHEIT,4300.0f,298.15f,10000.0f,10000.0f));
 Serial.println("*************************");

 delay(500);
}

I certainly would like one of these data logger devices...

• http://www.nuelectronics.com/estore/index.php?main_page=product_info&cPath=7&products_id=20
• http://www.nuelectronics.com/download/projects/sensor_shield_v1.0.pdf
• usage; http://sheepdogguides.com/arduino/ar3ne1tt.htm