Hi all,

  I would like to interface my LCD with my MSP. I've made this in the
past, but the LCD was powered from a 5 V supply because the
specification said that it was not able of work with less than 4.5 V.
My only solution was always write on the LCD.
  Now I've a 2x16 characters LCD in which Vsupply(min) is 2.75 V, and
I want to write and read from it with a 3.3V supply. I think there is
no problem. Anyone tested it before?

Regards.

yEP, YOU'RE ALMOST CERTAINLY SAFE TO GO AHEAD.

Al

linked82 wrote:

>Hi all,
>
>  I would like to interface my LCD with my MSP. I've made this in the
>past, but the LCD was powered from a 5 V supply because the
>specification said that it was not able of work with less than 4.5 V.
>My only solution was always write on the LCD.
>  Now I've a 2x16 characters LCD in which Vsupply(min) is 2.75 V, and
>I want to write and read from it with a 3.3V supply. I think there is
>no problem. Anyone tested it before?
>
>Regards.
>
>
>
>
>
>
>.
>
> 
>Yahoo! Groups Links
>
>
>
> 
>
>
>
>
>
>
>
>  
>

You can always buffer your 3V3 output from the MSP430 with a simple
74HC04 inverter.  (Be sure to double-buffer so your output is not
inverting.)  Power the inverter with 5V.  Since the logic-level high
is half the supply voltage (2V5), a 3V3 high from the MSP430 will
trigger the gate.  This method probably nominally violates the specs
of the 74HC04, but it will work.

If you have to read-back data from the LCD, you can do a similar trick
by powering another inverter with 3V3 and driving it with the 5V from
the LCD moldule.  This almost certainly runs the inverter out of its
safe operating region (inputs are 1V7 higher than the supply).  If
this is just a for-fun project, I wouldn't sweat it.  If this is for a
production device, you'll need something slightly more by-the-books.

You can try a simple transistor for each logic line pulled-up to the
desired output voltage, and driven by the source at its voltage. 
Remeber, this inverts the logic.

Have fun!

Stuart

--- In msp430@msp4..., "linked82" <linked82@...> wrote:
>
> Hi all,
> 
>   I would like to interface my LCD with my MSP. I've made this in the
> past, but the LCD was powered from a 5 V supply because the
> specification said that it was not able of work with less than 4.5 V.
> My only solution was always write on the LCD.
>   Now I've a 2x16 characters LCD in which Vsupply(min) is 2.75 V, and
> I want to write and read from it with a 3.3V supply. I think there is
> no problem. Anyone tested it before?
> 
> Regards.
>