Go Down

Topic: impossible to use I2c display (Read 1 time) previous topic - next topic

motodaddo

Hi to all,
i'm using arduino DUE with an optoisolated relay board for an autofiller water tank (230v solenoid valve) .
I'm using also an i2c  20x04 display, it works quite well when used alone, but every time a relay is energized, the display starts showing strange characters until arduino stops.
I tried to use DUE without display and relays work without problems and without arduino locks.
So I tried to use shielded control cables (for the relay), I tried to change the display i2c, relays board, I tried to filter the input current with capacitors (for decoupling), but was not able to run the relays along with the display .
They are about 2 months since I stopped at this point and I do not know how to go on ...
Have you any suggestions?
attached you can see the display used.
Thank you.

Peter_n

#1
Apr 10, 2014, 02:20 am Last Edit: Apr 10, 2014, 02:22 am by Peter_n Reason: 1
The background light of the display requires some current, and so does the relay.
Is that relay itself a 5V relay ? How do you power that ?

The first things to look at is the power and grounding, and the SDA and SCL.

Don't use ribbon cable for the SDA and SCL, keep those wires short and use short seperate wires.

How is the Due powered, and how the backlight and the relay ?

bperrybap

How is the backpack & LCD powered?
Is the backpack and LCD being powered with 3v?
Or are you using level shifters on the SDA and SCL lines?


motodaddo

#3
Apr 10, 2014, 07:46 am Last Edit: Apr 10, 2014, 08:13 am by motodaddo Reason: 1
Hi Peter, thank you for your answer.


The background light of the display requires some current, and so does the relay.
Is that relay itself a 5V relay ? How do you power that?

The first things to look at is the power and grounding, and the SDA and SCL.

Don't use ribbon cable for the SDA and SCL, keep those wires short and use short seperate wires.

How is the Due powered, and how the backlight and the relay ?

Display is powered by a 7805 well cooled and relays by a 5v stabilized  power switching (5A), commands are separate from power source.
DUE is powered by 12v stabilized power switching (3A) and SDA SCL wires are separte and of 15cm length.



chriskner

motodaddo,

Please provide a schematic that accurately represents all of your circuit (relay too).

In particular, there are surge suppression tricks when switching relays on/off that could cause some problems.

-Chris

gvs_ro

Are you connecting the GND to all the boards? I had a similar problem last week.

Go Up