2 LCD Serial Enabled

Hi. I would like to do something with 2 LCD. I have an arduino in a box, with a sparkfun 2*16 Serial Enabled LCD. (3 cables = Vcc, Grnd and Rx) This box will be used with another one, and the 2 will be connected with a subd-25 cable. (for different things) I would like to have an other LCD on the Second box that will display the same thing that the first LCD is showing. It's not usefull that the 2 works in the same time. And maybe 1 switch on the box 2 would be good to switch on its LCD and switch off the one on the box 1. I tought to do something like that, do you think it will work ? = Is a resistor will be enought to route Vcc on the LCD N°2, and what value should i choose ? 1K ? 10K ? the switch must be on the Vcc or on the Rx signal ? Both ? Maybe you have a better way to do this ... ? ::)

thk U !!

It will work if the Serial Display is written to e.g. every second. I had something similar with the serial monitor and a serial display. If the button is pressed after a second (maybe less) it will display the same.

However if you do not refresh the display the 2nd screen will not show anything until something is written to . This can be solved by adding a line from screen 2 Vcc to an Arduino IN pin (that is pulled down with a 10K) that when triggered will take care of refreshing the screens.

Switching screen 1 off requires another line and another type of switch

Does this makes sense to you?

Yeeeeeeeeah :o Ok, i didn't draw it perfectly, it is a on/off switch, not a momentary on switches ... Its not a problem for the system to reset the Arduino after switching the LCD, but your idea to refresh it with Vcc on a input pin is very good ! thanks !

Switching screen 1 off requires another line and another type of switch

What do you mean ? the simple fact that there is a Resitor will not switch off the LCD 1 when the LCD2 is ON ?

the simple fact that there is a Resitor will not switch off the LCD 1 when the LCD2 is ON ?

No, if LCD 1 works with the switch open it will also work with the switch closed. Due to the resistor it will be dimmer than LCD2 but that's about it. Maybe it will be more errorprone as it cannot do the serial logic at the right voltages. In short the resistor is a bad idea. If you are sure the two displays don't need to work simultaneously use an SPCO - single pole changeover - to select the display that needs

SPCO see http://en.wikipedia.org/wiki/Switch#Contact_terminology

OK. I thought signal would choose to go to LCD2 when switch closed because it would see less resistor. I missused it. Ok i'll go for a switch SPCO

TkU