Here's an old post regarding the use of a 5v i2c LCD display with the Raduino:
? ??
/g/BITX20/message/39966Summary:
The two wire i2c bus is also used to talk to the 3.3v si5351, so we can't operate the i2c bus at 5v.
Most i2c devices such as an i2c LCD display will include pullup resistors to 5v, they should be removed.
The 3.3v pullup resistors R13 and R14 on the Raduino are sufficient.
There should be only one set of pullups on the i2c bus.
If you try to put 10 i2c devices (such as LCD displays) on an i2c bus and they all have
their own pullups, it won't work.? The open-collector drivers will see too much current.
ArduinoLand has been running on 5v for the last 20 years, most of the world has since
moved on to 3.3v or less.? So hooking up a newer part like the si5351 to an Arduino Nano
is a bit more complicated than it should be.
Jerry
On Fri, Sep 7, 2018 at 11:15 AM, ajparent1/KB1GMX wrote:
The issue is that I2C requires level conversion.
The direct use of 20x4 line without i2C does not require that as the display is 5V.
But that needs 4 data and 2 control lines (d4-D7,R,E)
Where the converter board for i2c is 3.3V for the I2C bus and requries 5V for the display.
I believe that board will accept the 3.3V
I@C?from the controller and operates at
5V to suit the display.? ?Since I2C is used as a signal to the display that appears right.
>Sowohl 3,3V als auch 5V Logiklevel (@Spannungsversorgung 5V)
I believe that it accept either logic levels when powered with 5V.
My German is not so much.? But it would appear correct based on
a similar board I use for 20x2 line display.
The included document if from that vendor and shows hookup to a Uno and
only 5V power used. and the Uno signals are same as NANO as it is same
family MPU.
Allison
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