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Arduino RF remote LCD display of Temparature & Humidity

Aim of Project :- Transmit via RF remote values of Temparature & Humidity to a LCD display.

Why:- because i have always dreaded sending floating point values to a LCD display and

wanted to carve it in stone for other projects i have lined up.

& Why :- RF Links are just so cool 8-P        500ft range is not to be sneezed at......

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 Basic Setup :- 

 

1x Duemilanova ( this will be the remote transmitter with SHT10 sensor attached)

1x SHT 10 (0.5% accuracy) Temparature & Humidity Sensor or SHT 11 ( temp 0.4% accuracy)

1x Arduino Mega (this will be the Receiver with LCD display attached)

1x 2 line LCD display

1x RF Link Receiver

1x RF Link Transmitter

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Part 1 - The Transmitter Station

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        Temparature & Humidity Sensor

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The SHT10 (its marked ALP10!!!) is a low cost Humidity (0-100%) & Temparature Sensor (-40°C to 123.8°C)

Its a SMD device - here i have soldered it to a some recycled PCB board to make it easier to handle and mount.

Its a pig to extract the data - however i recently found a Library that does all the hard work.

 

 

(Sensor(pin 1 GND)to Arduino GND)
(Sensor(pin 2 DATA)to Arduino(pin 12)) 
(Sensor(pin 3 SCK)to Arduino(pin 13))
(Sensor(pin 4 VDD) to Arduino 3.3V)

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       RF Link Transmitter Module

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The Remote Arduino uses a RF Link to transmit data

Just 4 wires using cd audio socket to make neat connection.

Black connected to Ground

White is the transmit data cable connected to pin 3 on the Arduino (however this is easy to re-assign to suit your needs)

Red is the power supply connected to 5 Volt pin on Arduino (actually you can apply anywhere between 2 Volts and 12 Volts - the higher the voltage the stronger the RF signal)

Grey (sticking out of the Top is the Antenna - around 30cm long

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TX Code :- you find below in the attachements (RF_TX_TEMP_HUMIDITY_LMR_Gareth.pde)

Caution  :- you will also have install two libraries VirtualWire.h & SHT1x.h in your hardware/libraries folder.

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Part 2 :- The Receiving LCD Station
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2 Line LCD Display

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The LCD is a basic 2 line display attached to an Arduino Mega

 

 

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RF Link Receiver Module
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Only Four wires are required, i have used a audio cable from a cd drive which i rewired to accept the cables.

Yellow is the Antenna - approx 30cm long (other end connected to thin air)

Red is connected to 5 Volts

White is the Received data (in my case connected to pin 23 on the mega - can be easily assigned to another pin)

Black is Ground (it has three separate ground pins all connected together!!!!!!)

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RX Code :- you find below in the attachements (RF_RX_TEMP_HUMIDITY_LMR_Gareth2.pde)

Caution  :- you will also have install This modified library LCD4Bit_mod.h

or equivilant LCD4Bit.h library to suit your display

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AttachmentSize
RF_TX_TEMP_HUMIDITY_LMR_Gareth.pde2.61 KB
RF_RX_TEMP_HUMIDITY_LMR_Gareth2.pde1.23 KB

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Still not working (damn).

But at least I found out that datasheet is wrong: it says pin 3 is TX (in first page), but it's actually pin 2 (next pages)!! (Pin 3 does not even exist...)

But system keeps not working.

Weird thing is I'm receiving a very highnoise on RX pin on a TX/RX device, and nothing on same pin of the twin device if I invert the 2 devices. (tested by connecting RX and GND  to my sound card input).

I also added specific instruction for RX pin and TX pin. And I even changed serial monitor speed to 2400 (although I can't understand why it should matter).

Weird things happen: I logged both output pin of trasmitting arduino and output pin of 433 MHz receiver, and now I can see the received signal, but:

- it is inverted w.r.t. the original transmitted signal (i.e. I must put vw_set_ptt_inverted(true);  statement only on one Arduino)

- receiving Arduino cannot detect this signal

- signal still gets attenuated upon connecting RX board to arduino Vcc.

A really weird thing: if I disconnect RX from 5V power of the Arduino, I get a very strong signal. If I connect the power, signal strength is reduced to 1/100 !!

Why?!?

And, how can I know if this signal I see on RX pin is what I am transmitting?

http://img337.imageshack.us/img337/7721/rxwave.jpg

are those rf modules easy to use? i tryed using some hope RF12 modules 866mhz, very hard to use, i just quit after the 100th time trying
Yes these RF modules are real easy to use (with VirtualWire.h library) and they seem to be stable with very good range.

I go for quantity sneezing not quality.

1st sneeze takes you into the Back-yard (thats for the British and Europeans - not clear about spelling Meter or Metre).

2nd sneeze take you into the Ball-Park (thats for the americans, though old currency feet measurment is a bit long in the tooth guys)

3rd sneeze takes you into "Nirvana" (thats for the enlightened ones - no units as everthing equates to zero and everthing at same time !!!!)

1) thou

2) you

3) all 

I once sneezed at five hundred feet in a shoe store. They now have a restraining order against me. I cannot get any closer than 152,4 meter of that place nowadays...