first of all, taking time reading post.
summary:
one of 2 lcd not communication arduino when reed relay used.
i2c adress found though. works fine without relay.
long story
what trying easy.
i have aqurium monitoring system includes 2 lcd's.
after aquarium lights go off lcd's bright when sitting in room waching tv.
plan include reed relay between lcd power can switch them off @ time.
quick drawing testing:
the reed relay works fine , lcd's turn on , off here problem.
when include reed relay (sip-1a05) 1 of lcd looses signal arduino no text displayed lights up.
other 1 working fine. both lcd"s have different i2c adress ofcourse.
when switch wires same lcd not signal comming arduino.
now when bypass (remove) reed relay both lcd's text.
when reed relay used , no text showing show on i2c scanner.
i measures resistance 0.
installed second relay in paralell same issue.
it seems have lcd (both different brand) doesnt make sense. can me out or explain it.
thank you
summary:
one of 2 lcd not communication arduino when reed relay used.
i2c adress found though. works fine without relay.
long story
what trying easy.
i have aqurium monitoring system includes 2 lcd's.
after aquarium lights go off lcd's bright when sitting in room waching tv.
plan include reed relay between lcd power can switch them off @ time.
quick drawing testing:
the reed relay works fine , lcd's turn on , off here problem.
when include reed relay (sip-1a05) 1 of lcd looses signal arduino no text displayed lights up.
other 1 working fine. both lcd"s have different i2c adress ofcourse.
when switch wires same lcd not signal comming arduino.
now when bypass (remove) reed relay both lcd's text.
when reed relay used , no text showing show on i2c scanner.
i measures resistance 0.
installed second relay in paralell same issue.
it seems have lcd (both different brand) doesnt make sense. can me out or explain it.
thank you
when apply power system arduino starts running sketch beginning. the 'setup' part of sketch sends initialization commands lcd controller. these commands essential reliable operation of display.
the lcd controller has no non-volatile memory when remove it's power 'forgets' everything.
when reapply power lcd not receive required initialization commands since arduino sketch has not restarted beginning , running commands in 'loop'. this reason 1 display not function properly. why other display appears work when power reapplied mystery.
normally suggest use reed relay remove backlight power. this trivial problem standard parallel interface may not difficult i2c setup depending on i2c adapter have. if adapter has jumper enables backlight should able use reed relay in it's place control backlight.
otherwise solution involve turning backlight off software best technique in case. use simple light sensor detect when aquarium lights go on or off , issue appropriate commands turn backlight on or off.
don
the lcd controller has no non-volatile memory when remove it's power 'forgets' everything.
when reapply power lcd not receive required initialization commands since arduino sketch has not restarted beginning , running commands in 'loop'. this reason 1 display not function properly. why other display appears work when power reapplied mystery.
normally suggest use reed relay remove backlight power. this trivial problem standard parallel interface may not difficult i2c setup depending on i2c adapter have. if adapter has jumper enables backlight should able use reed relay in it's place control backlight.
otherwise solution involve turning backlight off software best technique in case. use simple light sensor detect when aquarium lights go on or off , issue appropriate commands turn backlight on or off.
don
Arduino Forum > Using Arduino > Displays > LCD's powered by reed relay. 1 gets no signal but has power
arduino
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