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Topic: 1602 LCD Display Power (Read 1 time) previous topic - next topic

Trickyrick

OK i was going to use a cat4 2pr wire just for power.  Would i be better to use the i2C packpack

Due_unto

I2C will not work over 25 feet, it was meant for comms between chips on the same board. 
You may want to consider a serial LCD interface like this one at
https://moderndevice.com/product/surface-mount-lcd117/
It needs only 3 wires to run, +5, Gnd, and Rx.  It also self initializes the display, does not need a LCD  library, and controls backlight intensity by commands.
The board attaches to the back of your LCD and accommodates single in-line or dual in line connectors.
Do not look into laser with remaining good eye.

wvmarle

Why is the Arduino so far away from the display?

And reading back in this thread... How are you going to get the signals from the motion sensor, pool temperature and outdoor temperature to the Arduino? What is the motion sensor even got to do with it?

It seems there may be many more issues with your project idea.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Trickyrick

Ok
I want to print out a 3d box to put the display in by the thermostat in the house.  The box would have to be to big for the LCD and the arduino.  I was going to put the arduino in the attic right by the access there is an outlet there and its about 25 ft from there to the thermostat. The motion sensor was to turn on the LCD screen when I walked up to it.  In regards to the temp sensors I have one working now on about 30 feet of cat5 works good.  So its about 35 feet from where the arduino is to the pool where the sensor will be the other sensor is only about 10 feet away.
If anyone has a better solution
Thanks

wvmarle

A Pro Mini is much smaller than a 1602 display.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Trickyrick

#20
Jun 27, 2018, 05:30 am Last Edit: Jun 27, 2018, 05:42 am by Trickyrick
Sorry what is a pro mini
OK I found it
I would still have to use something like the i2c backback
Never mind I see you don't use all 16 connections on the LCD. I would have to use the i2c backpack
Thats a good suggestion I will order one on Ebay now
Thanks

wvmarle

An I2C backpack for the LCD is not mandatory but makes life a lot easier. Less wiring mostly.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Trickyrick

Thanks
I was looking as a couple web sites I think the mini is 3.3v and does the 1602 lcd not require 5v

Trickyrick

OK that was dumb I can still power the mini with 5v and the LCD as well
Thanks for your help

sterretje

A pro mini can be bought in both 5V and 3.3V.

It's not a dumb question.
1)
You can not drive the inputs of a 3.3V device from a 5V device unless the inputs of the 3.3V device are 5V compliant.
2)
Driving the inputs of a 5V device from a 3.3V device usually works but you need to consult the datasheet of the 5V device to check Vih and Vil against the Voh and Vol of the 3.3V device to be sure.

With (1), you can damage the 3.3V device. With (2), there is no risk for that.
If you understand an example, use it.
If you don't understand an example, don't use it.

Electronics engineer by trade, software engineer by profession. Trying to get back into electronics after 15 years absence.

wvmarle

There are 5V and 3.3V versions of the Pro Mini. Main difference is that the first runs at 16 MHz, the second at 8 MHz (because the ATmega can't do 16MHz at 3.3V).
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

Trickyrick

OK thanks but from what I gather the LCD takes 5v from the 5v pin on say a Arduino Mega.  If if feed that Mega board with 5v then why cant I just feet the LCD from the 5v power supply instead from the pin on the Mega board.  If this is so then It wouldnt no mater if I had a mini at 3v or 5v because I think I can feed the mini with between 3v and 12v so I could feed it with 5v and feed the LCD as well.
Hope this is right.  I ordered the 5v anyway
Now just to make sure
Im going to use the mini with the iC2 backpack then find a library that has the commands noDisplay() Display() noBacklight() Backlight().  This will be turned on and off by the input from the motion sensor
Hope Im on the right track
The only thing is that the cable between the Pro Mini is going to be about 70 feet

bperrybap

OK thanks but from what I gather the LCD takes 5v from the 5v pin on say a Arduino Mega.  If if feed that Mega board with 5v then why cant I just feet the LCD from the 5v power supply instead from the pin on the Mega board.
You can.

Quote
If this is so then It wouldnt no mater if I had a mini at 3v or 5v because I think I can feed the mini with between 3v and 12v so I could feed it with 5v and feed the LCD as well.
Hope this is right.
No. This is where you are not thinking about the two devices talking.
The LCD and backpack are 5v, if you run the mini at 3v you now have 3v device trying to communicate with a 5v device.
This is what causes issues.

Quote
I ordered the 5v anyway
That will make things simpler as you won't have to worry about 3v to 5v logic level shifting.

Quote
The only thing is that the cable between the Pro Mini is going to be about 70 feet
Uh..... This is MUCH further than the 25 feet you said previously that we pointed out will likely have issues.

--- bill

Trickyrick

OK Bill thanks for all your help.  It was going to be 25ft when I was going to put the arduino between the LCD and the temp sensor so about 25 ft each way now with the mini Im going to put the LCD and mini at the same location. Ill see how much wire I can use when I get the mini.
One last question since im going to use a lot of wire for the 2 sensors would I be better off using separate pins for each temp sensor.  I was going to use them on the same pin
Have a good night
Rick

wvmarle

With 75 ft / 25 meters of wiring you have to keep other things in mind, such as EMI. That's a great antenna picking up all kinds of signals ranging from AM radio to the buzz of your 50/60Hz mains wiring.

What temperature sensor(s) are you using?

For this distance it may be easier and even cheaper to use a second Arduino at the sensors, then a wireless link (NRF24L01 or so) between the two. Those modules aren't big. You can consider putting it in a separate box, if you make the I2C/power wire between Arduino and display <1 meter it should go fine (maybe a bit stronger pull-ups, speed no more than 100 kHz).
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.

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