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Topic: Two I2C lcd displays did not work together (Read 7359 times) previous topic - next topic

-Micky

Two I2C lcd displays together did not work correct.

I try:

LiquidCrystal_I2C lcd2(0x20,16,2); 
LiquidCrystal_I2C lcd3(0x21,16,2);

In void setup:

lcd2.init();
lcd2.backlight();
lcd3.init();
lcd3.backlight();   

It works, but not long. The second display shows after some times wrong characters and some times later there are no more characters.


Micky

Riva

Have/can you set the displays to have different I2C addresses? A link to the display would help.
Don't PM me for help as I will ignore it.

-Micky

Yes, they have different addresses. I test this with a I2C scanner.


Micky

floresta

Quote
It works, but not long. The second display shows after some times wrong characters and some times later there are no more characters.

Swap the two displays (by physically changing the jumpers or switches that set the addresses) and then see if the problem stays with the display or the address, or if something else happens.

Don

bperrybap

What value terminator resistors are you using?

If you use each one separately do they each work ok?

--- bill

-Micky

Ok, I swap the physically addresses. Now I have on both displays the same.


Micky

Grumpy_Mike


Ok, I swap the physically addresses. Now I have on both displays the same.

So that suggests you did not change the address on one display.
You still haven't answered the question about pull up resistors.

-Micky


What value terminator resistors are you using?

If you use each one separately do they each work ok?

--- bill
I use two resistors each has 10 K. I tried 4,7 K but without success. I2C scanner did not find any addresses. 32,4 K works but, there are only errors on the displays.

Yes, I tried every display separatly.


Micky

-Micky

After changing the numbers in the sketch I have the same as before but now on the other display.


Micky

Grumpy_Mike


After changing the numbers in the sketch I have the same as before but now on the other display.

So that suggests it is you code that is wrong, you need to post it all using the correct code tags. If you don't know how to do this the the how to use this forum sticky post.

-Micky

#10
Apr 23, 2013, 11:01 pm Last Edit: Apr 24, 2013, 11:34 am by -Micky Reason: 1


After changing the numbers in the sketch I have the same as before but now on the other display.

So that suggests it is you code that is wrong, you need to post it all using the correct code tags. If you don't know how to do this the the how to use this forum sticky post.
Ok, I think the code must be ok, because with a single Lcd it runs.


Micky


floresta

We don't know for sure which specific display you are using since you haven't provided that information so a lot of what we are providing is speculation.

It is time for you to start over again with a simple circuit and sketch that just uses one LCD.  If that works OK with each LCD then change the sketch to use both LCDs
simultaneously.

I would add the other I2C device(s) on next and then the 1-wire device(s).  When things stop working you should have a pretty good idea of what caused the problem.


Don


-Micky


We don't know for sure which specific display you are using since you haven't provided that information so a lot of what we are providing is speculation.

It is time for you to start over again with a simple circuit and sketch that just uses one LCD.  If that works OK with each LCD then change the sketch to use both LCDs
simultaneously.

I would add the other I2C device(s) on next and then the 1-wire device(s).  When things stop working you should have a pretty good idea of what caused the problem.


Don


I use 16x2 LCD Displays of different brands. One is called: TC1602A. The other1602 QAPASS. And serial I2C IIC adapter called LCM1602 IIC.


Micky

-Micky

I think the reason is the I2C interface. It seems that only one address is possible. 0x20. I will make some changes to the interface and see what happens.


Micky

floresta

Quote
I think the reason is the I2C interface. It seems that only one address is possible. 0x20. I will make some changes to the interface and see what happens.


What about your response in reply #2 "Yes, they have different addresses. I test this with a I2C scanner." ?

Have you dealt with any of the jumpers (solder blobs) on either of your Serial interface boards?

Have you considered the recommendations in reply #11?

Don

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