turn-off lcd and turn-on again

i have a battery driven circuit.

there are a 2 * 16 lcd and buttons on it.

if it is not using , i use the sleep mode for low power consumption.

until new data comes , pic is in sleep mode.

there is no problem about the pics' entering sleep mode or wake up

the problem is ; i have turn off the lcd for power consumption if pic is in sleep mode.

i have tried to enable and disable the supply of lcd.but the current of the lcd does not decrease.

i have to turn off the lcd in order to turn the circuit into low power consuption

i use 18f1320 in intrc osc 4MHZ , lcd is in 4 bits - bus mode


i will be glad to hear your ideas about this problem

Quote:

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Originally Posted by mehmetOzdemir

i have a battery driven circuit.

there are a 2 * 16 lcd and buttons on it.

if it is not using , i use the sleep mode for low power consumption.

until new data comes , pic is in sleep mode.

there is no problem about the pics' entering sleep mode or wake up

the problem is ; i have turn off the lcd for power consumption if pic is in sleep mode.

i have tried to enable and disable the supply of lcd.but the current of the lcd does not decrease.

i have to turn off the lcd in order to turn the circuit into low power consuption

i use 18f1320 in intrc osc 4MHZ , lcd is in 4 bits - bus mode


i will be glad to hear your ideas about this problem

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mehmetOzdemir,

The LCD's power line will probably need to be switched on/off to get the LCD to totally power down. A transistor used as a switch to the 5v side would probably work ok, switching the ground side would probably not work as well since the other lines are still connected.

You could drive the transistor from a pin on the PIC to wake up when you wanted to display something. You will need to allow plenty of time for the LCD to do its startup before you get to send it data.

Just an idea,
Kevin

thanks for your idea.

i tried to switch both sides of the power supply.

still , power consumption is same.

1. Switch only the + supply. NOT the GND. Also note that if you do not have Backlight then you can omit the transistor and power the LCD directly from a PIC pin.

2. Put all lines from PIC to LCD at 0 level. If they are at 1 then these lines power the LCD.

Ioannis

Hi, Mehmet

In the Manual, LCDOUT Command Chapter, first page ...

You can find:

Quote:

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... if it's powered down and then powered back ....

ADD:

FLAGS = 0


The next LCDOUT Command found will re-initialise the LCD ...

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That's all you have to do ...

Alain

Hi Alain.

Thats the second he has to do :-)

First he has to turn it off.

Ioannis

hi alain and ioannis.

i switched vcc of lcd and made the other pins zero.when pic waked up i added flags = 0

and now working fine.

thanks for your response

Quote:

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Originally Posted by Ioannis

Hi Alain.

Thats the second he has to do :-)

First he has to turn it off.

Ioannis

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Hi, Ioannis

You're perfectly right on this point ... LOL !!!

Just need a PIC pin to drive a P Mosfet in the LCD Supply line ... eh !

I use a FQU11P06 ( I Pak case ) from Fairchild for my Lawn tractor onboard computer LCD ( The TRACTEUR program ... )

Note a BS250 should fit if using one of the lasts " Blue " displays ( Backlight current draw has been significantly reduced since old " green " displays ...

Alain