Electronics > Projects, Designs, and Technical Stuff
5V rail noise when updating 2x16 LCD
MasterT:
Have you powered LCD by 3.3V and interfacing by 5V logic?
Anyway, text display usually slow devices, put 10k in series with data lines. Other options would be to limit drive strength from the micro, stm32 has I/O slew control, not sure if pic has this future.
txescientist:
MasterT:
LCD and PIC are powered from the 5V.
PIC doesn't have that capability as I know.
AndersJ:
Could be capacitive coupling between conductors in the ribbon cable.
SiliconWizard:
Could be. Make sure there is at least one GND wire between the +5V wire and data lines in the ribbon cable...
But again, if the OP is certain there is no short-circuit of some kind due to a bad IO configuration or something, then it just looks like improper decoupling...
AndersJ:
Or bad probing, after all.
Probe ground loop, or coaxial connection?
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