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Interfacing LCD with the g2553

Anish
Intellectual 375 points
Other Parts Discussed in Thread: MSP430G2553

  Hi, I am having the msp430g2553 which came with the launchpad. I programed it with the LCD code for a 16x2 LCD. Actually, when interfacing the IC with the LCD on a breadboard, i used a 5 volt power supply. Everything was working correctly. But accidentally I came across the data sheet and it told max voltage to be given to the IC is 3.6 volts. Then I unpluged the powersupply and gave 3.6 volts (from the launchpad) and now in the LCD, the letters appear very dim and cant see it normally. What can i do for this?

Is there no other way than to opt for a level shifter or, can we use the msp at 5volts?

 Thanks.

Anish 

  • 0
    TI__Genius 10830 points

    Anish Karunagaran said:

    Hi, I am having the msp430g2553 which came with the launchpad. I programed it with the LCD code for a 16x2 LCD.

    ...can we use the msp at 5volts?

    The MSP430G2553 cannot be used with a 5 V supply (maximum voltage applied at VCC to VSS recommended to be 3.6 V).

    This mght be a good starting point to prototype.  Find, "2.4GHz RF + LCD BoosterPack," on this page.

    BoosterPacks for MCU LaunchPads

  • 0 in reply to Jason Work
    Intellectual 375 points

     Hi, thankyou for your reply,

    Is there no other way to do that other than ordering the booster pack?

     Thanks

  • 0 in reply to Anish
    TI__Genius 10830 points

    Anish Karunagaran said:

    Is there no other way to do that other than ordering the booster pack?

    There are numerous ways to design a MSP430 with an LCD display.  For example. the MSP-EXP430F5529 uses the EA DOGS102-6.  In this case, both the MSP430 and the LCD can be used at 3.3 V.

    Your restriction from the MSP430 is to design within the recommended specifications in the data sheet.  The rest is up to you.

  • 0 in reply to Anish
    Intellectual 840 points

    yes it is called " Split rail power " by some.  you take a 5V  and share ground on both devices and regulate to the needed less than 5V to the other devices.  As you are working with an LCD you should not need a buffer/line driver between the two to connect the lower to higher voltages to prevent data loss. 

    Alternatively, as it is an LCD, you could check the resistors on it for  the Contrast Adjustment.  You might get away with just changing the resistors for contrast with out the extra parts  needed for dual voltage designs.  One other thing, if it has a back light, i tend to make a simple blocking oscillator ( look up joule thief on the web ) using just a pnp, resistor and some coiled wire and a spare rf choke.  It tends to be quite bright with little current drain that way.

    Hope either option works for you,

    Eric

  • 0 in reply to Eric Blenner-Hassett
    Intellectual 375 points

     Hi,

    I used a simple voltage divider to give 3.3v to the MCU and 5v to the LCD. but both shared the ground.

    Now, I am getting the string on my LCD. But after sometime, the string changes itself to some garbage value. But after reset, it comes to original value and after sometime the same happens. Any suggesstions?

     

    Thanks 

  • 0 in reply to Anish
    Intellectual 840 points

    More Capacitors! I hate to admit forgetting this, depending how you split the power, I forgot to mention the possibility of the power differences causing " ghosting " due to the switching.  The only real work around is small value capacitors to " capture " the transient AC from the power to ground.  The most common is 15pF as close to the devices as possible.  If you check the signal length over time and compare the data speed, you can also sometimes get away with creating a RF filter on the data lines to do the same.  I have to assume that the whole thing is on a form of Bread Board ( not on a manufactured circuit board with a huge ground plane ) and can accept all kinds of RF interference ( or create it's own ).  Also you might want to check if you are getting a constant voltage AT the LCD as I have run in to an issue once ( long ago, but lesson learned ) that the electrolytic capacitor I had AT a display wasn't properly connected and thus the 5V line fluctuated enough to create a garbage out situation.  Since then, I have improved my soldering skills and tend to check voltages first for " weird output " issues on my own projects just in case I messed up on something again.

    Good work getting it this far, hope this will get you the rest of the way,

    Eric

  • 0
    Prodigy 100 points

    Hi, I am Guri and actually there is a way of getting +5v out directly from your launchpad, and that is sufficient for LCD kinna operations.

    Holding your launchpad, usb and emulator sections on top , just below the USB you will be able to see 2 Holes saying TP1 and TP3 , well actually TP1 pin  gives a +5v out, you can go ahead and solder a bugstick there for any further use , and for reference , TP2 actually is a GND pin. as these pins do not have any power protection, it is always better of using either a diode or a capacitor to the device you are connecting the +5 volt supply .

    and i interfaced LCD using

    https://sites.google.com/site/cacheattack/msp-projects/msp430-launchpad-with-lcd-module

    blog and it perfectly works , just need to connect the +Vcc i.3. 2nd LCD Pin to +5v rest should work fine just with 3.6v

    Hope i helped , Enjoy !!

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