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So im trying to give my lcd display (Lumex 1602) 5v. Im trying to use the test pins on my msp430 launchpad TP1 and TP3.

On the LCD pin 1 is gnd and pin 2 is power. for the launchpad TP1 is power and TP3 is gnd.

nothing lights up after plugging in the usb cable. Does mine just not have a backlight in it? How can i test to make sure its getting power and that it isnt broken?

*Edit So i got it to light up! Heres how i wired it: LCD Pin1 to gnd LCD Pin2 to pwr LCD Pin3 to Potentiometer. This is what drives the LCD display.

I used TP1(pwr) and TP2(gnd) which are test pins on the msp430 launchpad and provide me 5v power.

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The backlight is powered separately from the display, on pins 15 (power) and 16 (ground). These pins are connected directly to an LED, so you will need to connect a resistor in series to prevent it from burning out. 470Ω should suffice.

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  • \$\begingroup\$ according to my datasheet 15 and 16 are cathode/anode pins. is that the same thing as gnd and pwr? also i dont have an actual pin for the 16th pin. the prof had solder the pins onto the lcd but told us to not worry about the 16th pin. from the datasheet pin 1 is gnd and pin 2 is the 5v pin. \$\endgroup\$ – user2288023 May 6 '15 at 22:43
  • \$\begingroup\$ can you look at this? youtube.com/watch?v=QRlVQWmIGgM at around 23 minutes he hooks up the launchpad to the lcd but doesnt use the resistor(atleast not yet). i went ahead and wired it the same way he did. pin 16 to gnd and pin 15 to 5v. i dont see the difference here? unless mine is different than his and doesnt have a backlight \$\endgroup\$ – user2288023 May 8 '15 at 15:29
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The 1602 is a 5V hd47780 character LCD with LED backlight. It can communicate at 3.6V logic in, just barely matching what a msp430 Launchpad can produce. But it needs 5V for power. The valueline Launchpad test point TP1 is connected to Usb 5V, and can be used to power the LCD. What is key is the LCD Contrast Adjustment/Bias, which is PIN 3 VO. This needs a low voltage, often negative. For most purposes, this needs to be tied to GND for the display to show anything. If you skip that, you won't see anything at all, which is what I suspect happened to OP. Once you provide power, the LCD needs to be initialized like normal.

The LED Backlight often already includes a resistor so it can be directly powered or controlled by 5V, but it is good practice to check for one or include your own.

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