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e4rthdog
Posts: 10
Arduino MEGA.

I have been reading this thread: https://www.mobiflight.com/forum/topic/5870.html and iconnected 2 LCDs 20x4

I have changed the address of one of them by soldering the pins. So my 2 LCDs are in addresses 0x26 and 0x27. I tested them individually and they work ok.

When i connect both of them they work but it shows the same thing in both, even if my configuration is different.

https://postimg.cc/dhkkNBnW
https://postimg.cc/PPFvMcbp
https://postimg.cc/SJKzCq9b

Any way to make them work separately?
2022-01-14 16:06
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e4rthdog
Posts: 10
Could this be explained if i havent soldered well the change od i2c address pins in the back?
2022-01-14 16:32
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Whiteknuckle157
From: Bayern - Bibertal, Germany
Posts: 29
With multiple I2C slaves you might in some cases need two pullup resistors between SDA > Vcc and SCL > Vcc.
in most cases 4k7 may work fine.

good luck.
2022-01-14 20:38
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pizman82
Moderator
From: ETSI, Germany
Posts: 5128
Supporter
If BOTH Displays work fine when you test them "single" .... Then the second question make no sense....

icone4rthdog:

Could this be explained if i havent soldered well the change od i2c address pins in the back?



So if you confirm Display 1 work with Adress 0x26 BUT not work if you use for testing 0x27.....
And sametime Display 2 work with adress 0x27 but NOT work with Adress 0x26.....
Then you know Jumper are set correctly !

What whiteknuckle say....
iconWhiteknuckle157:

With multiple I2C slaves you might in some cases need two pullup resistors



I never heard this.... But i also never test myself a Setup with 2 Displays.
As said multiple times in other topics.... 1 Display work garantee.... I never see a usecase to use 2 on a Mega.... I simply connect another Mega and set them seperate.
Big advantage.... No change of Jumpers is needed.... 10 Displays on 10 Megas can be used all with 0x26 Adress for example.

BUT
May he is right.... Please try this and confirm if it work!. So we can include this in our Wiki/Guides.
Good Luck !
2022-01-15 21:25
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