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hayee
Joined: 05 Sep 2007 Posts: 252
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Distance between lcd and uC |
Posted: Mon Feb 15, 2010 1:41 am |
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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 do I have to use any protocol like rs485?
I also want to connect temperature and humidity sensors.
I am willing to use LM35 for temperature.
Which humidity sensor I will use. Can anyone tell me?
Thanks. |
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Ttelmah Guest
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Posted: Mon Feb 15, 2010 3:13 am |
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You need to be using a signalling standard like RS485.
RS485, is a _signalling standard_, _not_ a 'protocol'. You can choose your protocol to suit.
The maximum for TTL varies with frequency, and environment, but is somewhere around 10'. Realistically, it'd be much simpler, and more reliable, to add a small PIC at the LCD, and use normal asynch serial over RS485, to send what you want to display. It'd also be worth considering opto coupling, if you want this to have any chance of surviving very long....
You don't say what type of humidity measurement you actually want to make?. I'd guess relative humidity (the commonest)?. Simplest, probably the HC610. Just read the voltage with an ADC. Things like the HS1101, get more complex to drive, requiring 10v AC, or you have to purchase an entire module....
Best Wishes |
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Guest
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Posted: Mon Feb 15, 2010 4:42 am |
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Thanks Ttlemah.
ya have to use relative humidity. |
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bkamen
Joined: 07 Jan 2004 Posts: 1611 Location: Central Illinois, USA
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Posted: Mon Feb 15, 2010 10:51 am |
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Ttelmah wrote: |
It'd also be worth considering opto coupling, if you want this to have any chance of surviving very long....
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Indeed! I've used the parts from http://www.i-fiberoptics.com/ at 3.3/5 volt levels and they work great!
If you don't mind a lighting up your project a little, these are a great way to go.
-Ben _________________ Dazed and confused? I don't think so. Just "plain lost" will do. :D |
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arunb
Joined: 08 Sep 2003 Posts: 492 Location: India
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RE: |
Posted: Mon Feb 15, 2010 11:46 pm |
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Or even wireless ? Like the MRF24J40MA module from Microchip ??
Thanks
arunb |
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hayee
Joined: 05 Sep 2007 Posts: 252
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Posted: Mon Feb 15, 2010 11:55 pm |
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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? |
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