Distance between lcd and uC

[cool.man]

Hi,
I am using PIC16f877A and LCD.I am showing some data on LCD.
I want to know that how far i can place the LCD from microcontroller (my required distance is 250ft).I am using the 6 pins of LCD(4 for data and 2 for signals).Can i use this scheme for longer distance or i have to use any protocol like rs485.

I also want to connect temprature and humidity sensors.
I am willing to use LM35 for temprature.
Which humidity sensor i will use.Can anyone tell me
Thanks.

 

[amraldo]

The largest distance I did was 2 meters.
--
Amr Ali

 

[pranam77]

I have too handled upto 2 meters. But still you'll have to follow RFI /EMI precautions which may affect the circuits through the wires you are using.

 

[amraldo]

Do you think 250 ft is feasible?
I achieved the 2M with RFI/EMI precautions and sometimes at start up the LCD was not properly showing the figures. Their ration to total number of start ups were in significant. Thats why it was ignored.
--
Amr Ali

 

[wp100]

Hi,

For that kind of distance you want to use the little RF boards from Sparkfun, they are very cheap and have a max range of 500ft.
http://www.sparkfun.com/commerce/product_info.php?products_id=8949

The receiver must also have a pic chip which drives the lcd, both the tx and rx need to be used with Manchester coding as can be found here, otherwise you pickup all the stray signals.
http://www.winpicprog.co.uk/pic_tutorial12.htm

I used the cheaper SHT10 sensor with the remote pic to transmit the temp and humidiy to the base station - working lcd and rf receiver shown.

 

[cool.man]

Thanks guys

If i use rs485 signalling then will i have to be careful about RFI/EMI or not.
i think the range is in km for rs485.

 

[IanP]

The Rs-485 is pretty robust standard and 250ft is a piece of cake for it ..
You can even consider the Rs-232 which is easier to realize; <10m distance is still within its range ..

Rgds,
IanP

 

[pranam77]

Yes..i do agree with "IanP". You may have any of the said protocols...Cheers

 

[kender]

I am using the 6 pins of LCD(4 for data and 2 for signals).

What signals do you need to provide on these pins? If you could post the part number of your LCD or a link to the datasheet, that would help.

Few more questions to consider. Will your installation reside in industrial environment? How much EMI will it see?

Can i use this scheme for longer distance or i have to use any protocol like rs485.

I'll second Ian and Pranam that 250ft is very doable for RS-485, especially if the cable is shielded.

 

[engr_najam]

why not use wireless serial port adapters that have a range of about 300 feets.

 

[cool.man]

The option of wireless data transfer is good but i also have to consider the cost of the system.
What would be the min price of any wireless module,which will be reliable?

 

[pranam77]

The option of wireless data transfer is good but i also have to consider the cost of the system. What would be the min price of any wireless module,which will be reliable?

The ASK TX Rx pair (One which is shown in "wp100" s post above) costs just up to 400/- Rupees in India. It may be almost the same cost if you choose RS232 or RS485...Cheers

 

[arbj]

use the popular MRF24J40MA wireless modules from Microchip, they cost 9.95 USD for 1-25 pcs (duty and shipping extra).

I have bought several of these and they are much superior to the commonly available ones.

If you are designing for Industrial/commercial then a robust time-tested design would be advantageous.