Electronics > Projects, Designs, and Technical Stuff
5V rail noise when updating 2x16 LCD
AndersJ:
Good point mikerj, about micro end of cable.
Wrong end of cable will do no good.
txescientist:
Good idea MasterT,
Probed across 10k resistor (picture 1 print107).
Also, probed PIC side and LCD side. LCD side has 1V DC offset (picture 2 print110 and 3 print109).
T3sl4co1l:
Pics of layout?
Guessing there's a good chance you see the noise even probing ground to ground (i.e., clip the probe tip to the ground clip, and touch that to circuit ground). That means common mode noise, which means you don't have enough grounding and shielding around the signal traces, or the signals are going too fast, or...
Tim
Someone:
--- Quote from: T3sl4co1l on July 31, 2019, 10:37:54 pm ---Pics of layout?
--- End quote ---
Yes, this is where it would likely be revealed. Taking this cue:
--- Quote from: txescientist on July 31, 2019, 05:49:02 am ---Everyting is star grounded, but the LCD is daisy chained from PIC +V, GND and data lines.
--- End quote ---
Star layouts are usually misapplied, they can be required for extreme cases but for most cases perform worse than just using a plane/network ground. If you cannot explain where and how the isolation of separate wires for power or ground connections are needed, then you shouldn't use it.
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