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Index > MobiFlight Hardware & Firmware > Raspberry pico and 16x2 i2c LCD problems
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Message #27822
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ouuups_
Posts: 2
Hi guys,

I can't get a 16x2 i2c lcd to work with a raspberry pico. the wiring is correct, the address is correct, but nothing happens.
If I take the same lcd and connect it to an arduino mega, everything works.

Has anyone ever had success getting a raspberry pico and an i2c lcd to work with mobiflight?

Thanks for your help
2023-06-07 10:59
Message #27823
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elral
From: near EDDL, Germany
Posts: 50
Hello,

if using a LCD with a Pico you have to use a level shifter for the I2C lines! Search e.g. for BSS138 level shifter and you will find a bidirectional one.

The Pico is running on 3.3V, the LCD is running on 5V. On the LCD are PullUp resistors on the I2C lines to 5V, and if you connect these to the Pico you will exceed the max. input voltage which 3.3V. I hope you haven't damaged your Pico.

The other way round, connecting an output from the Pico to an input which expect 5V (e.g. a seven segment display which runs on 5V) does work in most cases but can not be ensured. I would also recommend to use a level shifter in this case.

Regards

Ralf

/edit: my 20x4 LCD is working without problems with a level shifter
2023-06-07 11:49
Message #27824
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ouuups_
Posts: 2
Thanks for your help, I will try to use a level shifter. I thought the pico was runing on 5V.

Regards
Eric
2023-06-07 13:26
Message #27825
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elral
From: near EDDL, Germany
Posts: 50
Hello Eric,
and connect the LCD to 5V. It might be that you have still to adjust the contrast.

Regards

Ralf
2023-06-07 14:36
Message #27839
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thatchi
Posts: 181
U can try to connect 5V to Vbus of pico . Remember to adjust the contrast .
2023-06-09 04:02
Message #27848
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thatchi
Posts: 181
And connect SDA to GP4 , SCL to GP5 . Tried and worked . However , LCD is always on since it connected directedly to the computer USB 5V bus .
2023-06-12 07:47
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Index > MobiFlight Hardware & Firmware > Raspberry pico and 16x2 i2c LCD problems