[HELP] Problem with LCD close to releys and contactors

[mrcube_ns]

I put mcu and LCD on one old machine with lots releys and contactors (for some additional controll).

Very offen (every few seconds) displey goes nuts, showing bad caracters shifting whole text to left or right and so...

I know that sparkings on contacts made problem.

Does someone have same problem, and how you solve it.


Thanks in advance!!!!


Mr.Cube

 

[on1aag]

Hi Mrcube_ns,

Have you tried putting in some power line filters ?
Put them in for both circuits so that power line disturbances caused by the
rattling junk have to pass trough two of these filters before reaching the
power supply of the LCD.
If that doesn't help, provide some shielding for the LCD and it's entire
circuitry, power supply included. Or use a shielded container for the LCD
and it's circuitry.
You can stop the arcing by bridging the contacts with this:

https://uk.farnell.com/jsp/search2/...arch_001&Ntt=RC+network&Ntx=&_requestid=60352

on1aag.

 

[bbgil]

common problems like this are caused by bouncing and arcing in the inputs. try putting in some debouncing circuits. another solution is isolation circuit. schmitt triggers are nice to do all this. hope this helps.

 

[IanP]

In "noisy" industrial environment filters and shielding is a MUST ..
Also, because many microcontrollers use only very weak internal pullups, you should consider adding external resistive pullups on all used pins ..

Regards,
IanP

 

[masud58]

dont tide lcd body to ground (leave open to the box) i have facing same problem when i build inverter,

thanks

 

[Shohdy]

Hi,

Make sure you put discharge diodes for the relays inductors.

Regards,
Shohdy