LCD shutdown

Hi,

I am using this LCD screen : http://www.futurlec.com/LED/BLUELCD16x2BL.shtml

I have seen that operating temperature start at 0°C. Then I would like to shutdown the LCD when temperature is under 0°C.

Is the method LiquidCrystal::noDisplay of LCD library to the good job to make LCD no operate ?

Thank you

I have seen that operating temperature start at 0°C.

I do not think that the LCD controller will be damaged if you try to operate it below this temperature but the manufacturer just does not guarantee that the display will work properly.

Is the method LiquidCrystal::noDisplay of LCD library to the good job to make LCD no operate ?

There is a difference between turning the display off and turning the LCD controller off. This command just blanks the display but the controller is still 'operating'. So this command will be sufficient to make sure that no incorrect information is displayed due to the low temperature.

Don

You can supply the +5V to power the LCD (typically pin 2 of the LCD) from a digital pin on the arduino. So you can completely power down the LCD if you want to.

When you power it on (either initially or later) you will have to initialize the LCD with lcd.begin if you do this. Ordinarily the power is on at the time the sketch does LiquidCrystal lcd (rs,rw,....); if you power the LCD from a digital pin, it will not be powered up when this statement is encountered. So you need to do the lcd.begin after you supply power to the LCD, typically in setup().

You can supply the +5V to power the LCD ... from a digital pin

But not the back-light.

Personally I would use a transistor to turn it all on/off, including the back-light.

Ok thank you floresta to give me insurance that the LCD will not be damaged when temp is under 0°c.

I have mounted the 1' and 14' pin to high level same wire on VDD.

So I thought like you jrraines, about putting this wire on a digital output of arduino but now I wonder about gardner's remark. I think there is a problem of current level provide to both 1' and 14' pins of LCD.

Can you confirm to me this potential problem?

My goal is to power on the LCD only when an ultrasonic sensor detect me walking under my arduino box.

This arduino box will be outside my home at 2,5 meter height.

Thank you by advance for your response.

supplying the backlight from a digital pin works for some displays, too. You need to carefully read the datasheet and see how much power it draws for the backlight. There is a risk of damaging that Arduino pin if the backlight draws more than 40 milliAmps. Displays that I’ve purchased from adafruit, hacktronix etc have frequently been able to power the backlight from a digital pin.