Power issue with Serial LCD

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Power issue with Serial LCD

Post by Zedax » Tue Apr 17, 2012 2:23 am

Hello i have problems with a Serial LCD, my unit only works powered on the digital ports like, pinMode(10, OUTPUT); digitalWrite(10, HIGH); for 5V, and then gnd, rx & tx on pins 11-12.

If i connect vcc & gnd to the 'power' area near the analog ping it does not work, just the green led.

Any idea why? it doesn't make sense, also it doesn't work when powered with an independent 5v source.

This is a problem because digital pins only provide 40mA as maximum, the lcd works fine without backlight, but with the light enabled it doesn't have enough power, since it uses 75mA.

So i can't use the backlight..

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Re: Power issue with Serial LCD

Post by marekm » Tue Apr 17, 2012 2:47 am

Hi Zedax,
Power supply for SerialLCD should be from power conectors - oposite side to pins 10,11.
On "power side" you have pins: reset, 3V3, 5V, GND, GND, Vin, then in next segment analog pins 0 to 5.
You should take GND and 5V to supply Serial LCD and 10,11 pins as signal TX,RX - it work fine for me.
SerialLCD module require +5V supply. When connected to +3.3 - control leds on module light propper, but module not working propper.

It is also possible to use external power source +5V, bu in this case you should connect both GND - from Arduino board and from your external power source, in other case - RX and TX signals on SerialLCD have no GND connection to Arduino.


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