Cannot get LCD to work

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Drowwy
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Cannot get LCD to work

#1 Post by Drowwy » 26 Dec 2018, 14:54

Hi, I'm on build 20181220 on a Nodemcu V3. I try to connect an LCD 2004.
On the I2C scan it finds the lcd on address 0x27.
Now, when I enable the device and write "IP %ip%" on the first line, the display remains blank.
Also, I'm not really sure what interval is for.
Thanks for any hints.

RobertM
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Re: Cannot get LCD to work

#2 Post by RobertM » 26 Dec 2018, 17:33

Do you connect "VO" pin (contrast) :?:

Domosapiens
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Re: Cannot get LCD to work

#3 Post by Domosapiens » 26 Dec 2018, 18:17

potmeter adjustment ?
30+ ESP units for production and test. Ranging from control of heating equipment, flow sensing, floor temp sensing, energy calculation, floor thermostat, water usage, to an interactive "fun box" for my grandson. Mainly Wemos D1.

RobertM
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Re: Cannot get LCD to work

#4 Post by RobertM » 26 Dec 2018, 18:25

yes

Drowwy
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Re: Cannot get LCD to work

#5 Post by Drowwy » 01 Jan 2019, 16:58

Hey thanks for the reply. I connected the four pins GND,VCC,SDA and SCL.
EDIT: The tip with the potmeter helped but the highest contrast is still barely visible.

Drowwy
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Re: Cannot get LCD to work

#6 Post by Drowwy » 01 Jan 2019, 17:16

The text is weak in dark color instead of being bright and white on the blue background.

Domosapiens
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Re: Cannot get LCD to work

#7 Post by Domosapiens » 01 Jan 2019, 17:42

Display needs 5V.
Use a level-shifter for SDA and SCL.
30+ ESP units for production and test. Ranging from control of heating equipment, flow sensing, floor temp sensing, energy calculation, floor thermostat, water usage, to an interactive "fun box" for my grandson. Mainly Wemos D1.

Drowwy
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Re: Cannot get LCD to work

#8 Post by Drowwy » 01 Jan 2019, 18:21

Okay, I will try that, thanks.

Domosapiens
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Re: Cannot get LCD to work

#9 Post by Domosapiens » 01 Jan 2019, 18:50

30+ ESP units for production and test. Ranging from control of heating equipment, flow sensing, floor temp sensing, energy calculation, floor thermostat, water usage, to an interactive "fun box" for my grandson. Mainly Wemos D1.

Drowwy
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Posts: 8
Joined: 26 Dec 2018, 14:49

Re: Cannot get LCD to work

#10 Post by Drowwy » 01 Jan 2019, 19:20

As I am a beginner that line didn't ring a bell for me when I read it.
Luckily I have bought plenty of different parts in advance and I found a level shifter.
Now it works like a charm.
Maybe the wiki entry could be dumbed down for beginners like me, that think it's enough to plug&play.
Anyways, thanks a lot for the advice. I'm looking forward to play with that lcd :D

(for beginners like me: lv is 3.3v, gnd is gnd, lv1 is sda old, lv2 is scl old
then on the other side: hv is 5v source, gnd is correlated gnd, hv1 is sda new, hv2 is scl new)

velja
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Re: Cannot get LCD to work

#11 Post by velja » 12 Dec 2019, 09:57

I like to sugest to author of plug-in for I2C LCD 2004 to extend range of I2C address to 0x4f (http://www.ti.com/lit/ds/symlink/pcf8574.pdf page 13 ).
Thank you

TD-er
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Re: Cannot get LCD to work

#12 Post by TD-er » 12 Dec 2019, 11:27

velja wrote: 12 Dec 2019, 09:57 I like to sugest to author of plug-in for I2C LCD 2004 to extend range of I2C address to 0x4f (http://www.ti.com/lit/ds/symlink/pcf8574.pdf page 13 ).
Thank you
I added an issue for it, so it will not be forgotten.
See https://github.com/letscontrolit/ESPEasy/issues/2813

velja
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Re: Cannot get LCD to work

#13 Post by velja » 12 Dec 2019, 11:44

Nice,
Thanks!

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