Interfacing msp430135 whith a 5V 2x16 character lcd screen

ks0066 msp430

I realize problems connecting a (3,3V) msp430f135 with a standard 5V 2x16 lcd. As far as i know, msp430x1xx doesn't have 5V tolerant pins. That means at least it is not recommended to accept as an input logic levels of 5V, right? But in MANY commercial development boards with msp's i have see direct connection of PORTx to a 5V lcd.
My problem is this: when reading from lcd, the VCC voltage start to GOES UP! If the LCD remains in output mode (the msp reads the output of lcd as logic levels of 0V and 5V) the VCC voltage from 3,3 goes up to 4+Volt. Now, a normal read from lcd (busy waiting) last as long as to cause a peak to VCC about 0.4V and causing no other problems(in my design). With no oscilloscope you cannot see this peaks in VCC, but i found this problem realizing unexpected hangs and error messages during flash download for debugging (iar).
So my questions is: Have any other realize these symptoms interfacing direct an msp to a 5V 2x16 lcd? Maybe i have a problem, miss something? It is recomended to connect a 3,3v msp to a 5V lcd and if yes why? The commercial dev boards is a compromise design for saving the cost of a logic translation, assuming that no read is done from the lcd and if its done, it lasts to short to cause problems from being noticed?

(Sorry for the english i do my best )

lcd 2x16 3.3 v

Hi

Most of the 5V LCD can work on 3V signals (the LCD must be powerd from 3V rails )

Otherwise you will need 2 power sources 5V and 3V and a level converter

See TI site for MSP430 application note - there is one APP note who describe how to use MSP430 on 5V rails

You will probebly need some level converter : resistor divider for signals drived from the LCD module

BR

Bobi

msp430 and 5v lcd

Hi
U can use 74lv4245 which is level translator with direction pin.which will solve your problem

how the charecter l.c.d work

Hi!
Another option is to use a LCD that works on 3.3V.
LCDs with the KS0066 driver goes from 2.7 to 5 v so they work.
In this case, you will need to provide a small negative voltage for the contrast.
In that case, you can use a DCDC converter or maybe using a PWM output you can construct a simple switcher to provide that negative voltage.

ks0066 hangs

Most LCD modules work at 4.5-5.0v, so I prefer 74lvt245 as level translator.

Mike

character lcd 3v

U can find the LCD work at 3.3V