studio72
Posts: 16
Joined: Fri Nov 17, 2017 8:54 pm

LCD Noise

Sun Aug 19, 2018 6:59 pm

Hi guys,

I rely need help, i can't solve my issue with 20x4 lcd.
I trying to command one board with 2 relays, board is with optocuplers and is power from different supply.
Also I read an input from one ambient thermostat, and base on sensors read I'm trying to command 2 relays.
Everything works perfect without LCD, On LCD sometimes appears some noise.
I tried different solution, I installed also 2 capacitors (100micro and 100n) on display, but without success.
If some one have any clue I will by very grateful.

Please see picture from http://www.studio72.ro

Thanks in advance

pcmanbob
Posts: 4266
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: LCD Noise

Sun Aug 19, 2018 7:18 pm

A corrupt display like that is normally the result if incorrect data being send to the display, either because if an error in your program or the driver you are using, or a fault in the connection between the pi and LCD.

what sort of connection is there between the pi and the LCD ?
Remember we want information.......................no information no help
The use of crystal balls & mind reading is not supported

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FTrevorGowen
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Re: LCD Noise

Sun Aug 19, 2018 8:45 pm

pcmanbob wrote:
Sun Aug 19, 2018 7:18 pm
A corrupt display like that is normally the result if incorrect data being send to the display, either because if an error in your program or the driver you are using, or a fault in the connection between the pi and LCD.

what sort of connection is there between the pi and the LCD ?
+1 and/or possibly e-strobe timing issues,esp. if 4-bit cf. 8-bit interfacing is in use, see my notes here:
http://www.cpmspectrepi.uk/raspberry_pi ... gData.html
Trev.
Still running Raspbian Jessie on some older Pi's (an A, B1, B2, B+, P2B, 3xP0, P0W) but Stretch on my P3B+, P3B, B+, A+ and a B2. See: https://www.cpmspectrepi.uk/raspberry_pi/raspiidx.htm

studio72
Posts: 16
Joined: Fri Nov 17, 2017 8:54 pm

Re: LCD Noise

Tue Aug 21, 2018 6:49 am

Hi,

I think i found my issue.
With one relay from relay board I'm trying to command one pump which is powered by 220V, I'm using relay as switch for this.
I saw that when relay is activated by PI appears this noise on LCD, if I remove the wires from relay contacts LCD it's working without problem.
But unfortunately I don't know to solve this and need help if someone have any idea, how can I separate this noise from 220V ?

Thanks

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