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Thread: Standby problems with Lcd

  1. #1
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    Post Standby problems with Lcd

    Im using a Laptop with the battery in it. Its set to go into standby when the battery is used. When the car is on the battery is charged. Anyway... Ive been using standby mode to get it to boot in about 4 seconds. This is sooo nice. And standby is great because it draws off the battery power and not my car battery. If the laptop battery goes dead its no big deal. The problem with standby is that i dont think the LPT port likes it. It wont wake up from the standby. The lcd works fine until i go into standby mode and after that the backlighting just turns on...no display.

    Any ideas?

    Thanks

  2. #2
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    I assume that when the car is off and the laptop is in suspend mode that the LCDs power is disconnected(i.e. the LCD is not powered by the laptop but is switched off by the ignition). If this is the case it will cause the LCD to reset when it is powered up again. The lcd needs to be initialised after a reset and the software on the laptop wont do this because it doesnt know the LCD has been switched off. The only way to make this work would be to keep the LCD powered when the car is off. You could have it turn off the backlight and turn the contrast down so the LCD uses virtually no power. That way it wouldn't flatten your battery.

  3. #3
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    so youre saying that if i keep +5V going to the LCD it will work when the computer comes out of standby? Can you explain whats going on in the LCD while all this happens so i can better understand the problem?

    [ 10-24-2001: Message edited by: Alives ]

  4. #4
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    Okay. When the LCD is connected to your parallel port and first switched on it requires some commands to initialise it so that it will work properly. The software that drives the LCD(i.e the winamp plugin, TSR etc.) send these commands when it is first run. After the display is initialised the software only needs to send the LCD the text it wants displayed(plus commands to clear the screen or position the cursor etc.). If the power is cut to the LCD it will reset and need to be initialised again, but after the laptop resumes the software will continue where it left off and wont initialise the screen again. If you dont cut the power to the LCD it wont reset and wont require initialising when the laptop resumes. I hope this explains it better for you

    [ 10-24-2001: Message edited by: Technics ]

  5. #5
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    thanks thats perfect!!! i'll find a solution asap! so happy to be back to the 5 second boots!

  6. #6
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    so after doing some thinking im gonna go with this solution:

    take the always on 12V from the cig lighter wires and run these to a car cd player adapter or something from radioshack/walmart that will provide 5V from that source. I'll run this to the lcd to keep it on at all times. The backlighting power will still be supplied by the computer so it will turn on with the computer and turn off when the computer is in standby mode...sound good?

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    Most cigarette lighter sockets arent allways on from what I've seen so just make sure. You could use an LM78L05 to get the 5 Volts to power the display they only draw a few mA if they arent powering the backlight.

  8. #8
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    I have to slightly disagree with the LCD problem.

    I am also using a laptop (well actually a pad computer). If I hit the standby button, everything went dark like it is supposed to. When it came back on the LCD worked like it should.

    I would try starting winamp after doing a start from stby and test the lcd. Just like a printer, you can hot plug them if you are daring...the initialization comes with the first access from the print program...in this case your winamp plugin.

    It also depends on the plugin, winLCD seems a bit flakey on the startup from standby, but lorty seemed fine.

    I have been using a program that does a quick shutdown to standby. It will kill whatever program you tell it to automatically before going to sleep, then start it up after the wakeup. That seems to give me better luck with the lcd.

    Sleepsmart http://www.digitalminer.f2s.com

  9. #9
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    I think the problem is that Alives wants to go into standby with winamp running and resume again without restarting winamp. If this is done the plugin will start running where it left off and wont initialize the display.

    [ 10-26-2001: Message edited by: Technics ]

  10. #10
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    Actually that is a good idea DodgeCummins. Alive could use SleepSmart to shutdown winamp and have it restart automatically. If he installed the resumer plugin the music would continue where it left off.

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