Turn off sensor and lcd to reduce the power

Hi guys, i want to make an auto watering Arduino powered using solar panel and batteries so the most important is reducing power, i will use a barebone atmega328p and using sleep library to make the board sleep 10 min and wake up for 30s to read the Soil Moisture and humidity sensor.
By the way, i want to ask you :

1- how can i turn off these sensors when the Arduino in sleep mode to reduce the power?

NB: The Current of The soil moisture sensor 35mA.
The current of the humidity sensor 2.5mA

2- Maybe i will add a 1602 LCD, how to turn off also?

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For the LCD what is better , turning off only the backlight or also the power ?

Check the specs or just make a test! Backlight is probably consuming a lot more current than the LCD. Turn backilgth off and keeping the core of the LCD sounds like possible.

Railroader:
Check the specs or just make a test! Backlight is probably consuming a lot more current than the LCD. Turn backilgth off and keeping the core of the LCD sounds like possible.

Because i want to use the LCD just 1 or 2 times in week !
Why i need just turn off the backlight and not the all lcd ?
and how much current draw the lcd when the backlight is off ?

Measure it.
Have seen numbers in the 20-140mA range for the light, but that could vary between different LCDs.
The LCD chip itself uses ~350uA according to the datasheet .
Leo..

Look at the LCD as 2 units, the lowpower core of the LCD and the highpower, thursty backlight.

Wawa:
The LCD chip itself uses ~350µA according to the datasheet.

Ah yes, but there is the 11k bias ladder and a bad blunder inherited in almost all designs from a misleading original datasheet.

A 10k potentiometer is cited between ground and 5 V. If connected as such, this wastes another 500 µA on top of the 450 µA in the bias ladder. Do not connect the potentiometer to 5 V, just to ground and Vo (connect the "free" end to the wiper instead).

If you can cut such a connection on each module you have, do so - this will also improve the ease of contrast setting and if constructing it anew, use a 1k pot instead for even easier contrast control.

One question is the rathio of sunshine, and battory charging, versus non battory charging conditions.
What current consumtion matches or is below the energy You gain? How much do You need to cut down power consumption?

So to turn off only the Backlight i will use this

And to turn the all lcd i will use this , and set the data pins as input like mentioned in this topic

Link of topic

Didn't read - or comprehend - my post, eh?

Paul__B:
Didn't read - or comprehend - my post, eh?

I did not understand well :frowning: , can you explain more

See the connection of the 10k pot to 5 V on your diagram? Disconnect it!. Do not connect the potentiometer to 5 V - it was a mistake that someone made when these things were first used and has been copied mindlessly again and again since because users - even supposedly competent engineers - simply have no idea how the thing works (or are simply careless, which is essentially the same thing)!

And in fact, since you show it as connected straight to 5 V, it would not even turn off when you switch your BC558 off!

When you disconnect it, you can also connect that end back to the wiper like this:

Paul__B:
See the connection of the 10k pot to 5 V on your diagram? Disconnect it!. Do not connect the potentiometer to 5 V - it was a mistake that someone made when these things were first used and has been copied mindlessly again and again since because users - even supposedly competent engineers - simply have no idea how the thing works (or are simply careless, which is essentially the same thing)!

like that to turn off only backlight ?

This correction of the circuit - you have it shown correctly there - is completely unrelated to turning off the backlight, the liquid crystal, or both. It is simply a correction which applies to all these modules under all circumstances.

My comment was that you were showing a diagram where you turned off the liquid crystal (pin 2) and the backlight (pin 15) but oddly omitted to "turn off" the potentiometer at the same time. :astonished: