Automatically turn on KT-LCD3

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dushad   1 µW

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Automatically turn on KT-LCD3

Post by dushad » Mar 08 2018 1:03pm

Hi guys,

I have installed controller switch on my handlebar, and I really would like my KT-LCD3 to turn on automatically when I turn on the controller.
Is there any way to do this beside "pressing" (imitating) turn on button in KT-LCD3 ?

Probably this question was already discussed here, but I couldn't find anything.

Thanks.

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fechter   100 GW

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Re: Automatically turn on KT-LCD3

Post by fechter » Mar 08 2018 2:17pm

You could possibly place a jumper in the display that goes across the internal transistor switch so it's just always on. I don't know the layout of the display and where this would go but with a voltmeter it should not be too hard to find.

Between the controller and display, there is one wire that is always connected to B+ and one wire that gets energized when you turn it on. If the display comes apart without damage, you could probe around and find it. If the display is sealed/potted, then you could do it at the controller end or in the middle of the wire.
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amberwolf   100 GW

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Re: Automatically turn on KT-LCD3

Post by amberwolf » Mar 08 2018 2:21pm

fechter wrote:
Mar 08 2018 2:17pm
You could possibly place a jumper in the display that goes across the internal transistor switch so it's just always on.
The same thing can be done by jumpering at the cable connector to the controller from the display, as far as that goes, wihtout opening the display.


However, it's possible that while that would turn on the controller always, it might still require the buttonpush to wake teh display's MCU. It does on my Fusin's LiShui / KingMeter combo.

And on mine, IIRC, wiring across the button itself doesn't work because that same button is also used for other functions once it's awake. :(

docw009   10 kW

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Re: Automatically turn on KT-LCD3

Post by docw009 » Mar 12 2018 11:44am

The jumper turns on the controller, but doesn't turn on the LCD3. If you turn on the LCD, using the middle button, then it will apply whatever PAS level is set as default, and work normally.

If you leave the LCD off, the controller will be powered up with throttle and PAS enabled. Unsafe in my opinion to have a dark LCD and a powered on bike. I've accidentally bumped the throttle while walking my bike and had it pull a wheelie. It could also take off if someone tried to position the pedals. I like to see the LCD off or in PAS 0, and know it's a dead bike.

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fechter   100 GW

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Re: Automatically turn on KT-LCD3

Post by fechter » Mar 12 2018 2:19pm

Then about the only other approach I can think of is to make a circuit that will simulate pressing the button for 2 seconds when the power is applied. This could be done several ways. One would be a timer chip like a 555. Another way might be to use an optocoupler with a big capacitor and resistor in series with the input wired to the controller. When the controller gets powered, the cap would pass current until it becomes charged, then it would turn off the optocoupler.

Dumb question: what's wrong with using the button going to the display like it was originally?
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eCue   10 kW

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Re: Automatically turn on KT-LCD3

Post by eCue » Mar 13 2018 9:32am

dushad wrote:
Mar 08 2018 1:03pm
Hi guys,

I have installed controller switch on my handlebar, and I really would like my KT-LCD3 to turn on automatically when I turn on the controller.
Is there any way to do this beside "pressing" (imitating) turn on button in KT-LCD3 ?

Probably this question was already discussed here, but I couldn't find anything.

Thanks.
The controller turns on automatically with the display
Easy fix is remove that pesky handle bar switch you added and start it as normal.The handlebar switch would work well as a engine power cut off / brake cut off
Solar charge station on wheels join the Revolution

dushad   1 µW

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Re: Automatically turn on KT-LCD3

Post by dushad » Mar 31 2018 5:40am

Hi guys,

Thanks a lot for your advises.
I finally got back to this and that's how it all ended:
- KT-LCD3 turns on if +48V are supplied to control wire for 1 second (both devices I have behave same way). MCU doesn't require anything else to wake up and keeps the power from this point. You typically need around 100 mA (10-20 mA for LCD3 power up, rest to compensate controller consumption).
- I already had my own MCU for some internal needs on my bike, so I simply added small transistor key and used one of unused digital pins. I set this pin to HIGH for 1050 ms at startup sequence. So LCD3 comes on at power up, but I still can turn it off with power key if needed. I typically don't. I also now have the possibility to use my alarm remote to power up the bike (and drive without ignition key), not sure if I will need this.
- Ignition key is connected between LCD3/my circuit and B+ (and LCD3 gives power to controller itself), so controller can't be on if LCD3 is off, unless my transistor key will suddenly start leaking 100 mA (resistor won't allow more than this) unnoticed - but this probably has around same probability as me leaving the ignition key on, bike unattended, LCD3 key transistor leaking and even then it will require somebody touching the throttle (or throttle control to go crazy). Probably there is a higher chance of me being hit by meteorite, when riding this.
- And yes, it isn't a big deal for someone probably - but for me this repetitive action of pressing button for 1 second after each ignition key turn is a nuisance. Now it's much better.

Thanks again for your help. :)

How it looks: https://imgur.com/6uPswig

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