Need Assistance - EMI Issues with 16x2 LCD Display (Model BCB-1602-03C)

[Yogesh D]

Hello Arduino Community,

I am Yogesh D from Trident Pneumatics Private Limited, R&D Innovation - Electronics. We are currently using a 16x2 LCD display (model BCB-1602-03C) in the controllers (parallel connection) of our dryers. However, we are encountering significant EMI issues that are affecting the display's performance.

The specific issues we are facing include:
- Distortion of characters on the display
- Discoloration and character mismatch

We are using the PIC 16F 876A - E/S P microcontroller in our circuit. I have attached the schematic diagram of our current setup for reference.

We would greatly appreciate any guidance or suggestions from the community on how to resolve these EMI issues.
We would be very thankful if any of you resolve the issue and give the altered schematic diagram.
If anyone has encountered similar problems or has experience with EMI mitigation for LCD displays, your insights would be invaluable.

Thank you in advance for your assistance.

 

[barry]

First of all, how do you know it's EMI issues and not, say, a power supply issue? If you do know it's an EMI issue, then you must know what the source is and how it's getting into your circuit. Is it conducted? Radiated? What's your environment?

You can try adding ferrite beads. You can try shielding. You can try fixing the EMI source.

 

[KlausST]

Hi,

EMC is not only about schematic. I´d say the more influence has PCB layout, wiring, cable length, signals nearby....
Thus we need to see the whole story.

Klaus

 

[scopeprobe]

Your using a LN2003 which suggests you could be switching something potentially quite noisey - possibly solenoids being pneumatics company. Cable/wire routing will be important as will proximity between your LCD lines and these switching lines. Some resistance in the digital lines from the PIC to the LCD would be beneficial as would a few hundread pf of capacitance down to 0V to soften the edges of the datalines to it.

 

[betwixt]

also - and maybe a quick fix: if the "J" connectors on the top right are feeding solenoids, consider connecting pin 9 of the ULN2003 to the +24V line so its internal diodes catch reverse voltage spikes.

Brian.