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    jwsusa reacted to cde in Noobie: power a sensor off an I/O?   
    8ma, you could do it straight from a output pin. You might want to add a resistor, but even without one. At 8ma, you won't have any noticeable voltage drop, so it will be as stable as your msp's v+ is.
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    jwsusa reacted to larsie in LCD and Touch booster pack   
    Yes. The v2 and v3 boards (now in store) have space for a mosfet to turn on/off backlight via IO, but I haven't tested it yet so these aren't soldered on by default. Planning to test it this weekend and can get back with info. I'll also test how much the backlight actually draws.
    Edit1: The mosfet works, and you can control the backlight from Port 2.5. The mosfet is a 2N7002PW, SOT323. I'm using this one.
    Edit2: It is probably possible to drive the backlight directly from the IO if you have a large enough resistor in-between. I didn't realize this until now. The backlight draws 4 mA at 3.6V if you use a 150ohm resistor in series with the backlight. If you run the backlight at this voltage without a resistor it draws about 30mA, which is too much and will probably trigger the current-limiting feature on the IO port. If you increase the resistor to above 200 ohms, which still gives an ok light, you should comfortably be able to use the IO directly without a transistor. You can always measure it to make sure before you connect it to the IO port.
    If you let me know which board you're using I can let you know exactly how to wire it, but you can also look the schematics on http://lars.roland.bz/lcd/ (click the sub-page for the version and type of display you have).
    Basically, (IO-port) --- (resistor) --- (backlight-connector)
    It is the ground-side of the backlight that is available, so you need to drive the IO-port low to light up the display.
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