Re: ic2 display problems #arduino ??? #arduino

Tom, wb6b
 

Hi,

Just a couple of general observations about I2C displays.

Yes, the I2C display uses the same pins as the SI5351 (A4, A5) for the interface connection. The SI5351 is a 3.3V part and the bus is set up to use 3.3V levels. The interface between the SI5351 and the Arduino relies on the 3.3V high level barely being in spec for the minimum acceptable "one" voltage for the Arduino (depending on which ATMega324 data sheet you look at). I believe the displays work just fine at the 3.3V bus levels.

Your display physically looks just like mine, however there are some that have the order of the data bits reversed. It seems some people/companies have modified the LiquidCrystal_I2C library for different parts/configurations and kindly kept the name the same. So there are several libraries and they may not all be compatible. To work with the CEC firmware the display should be using the PFC8574 I2C to parallel chip. 

It looks like the CEC firmware has included all the I2C LCD driver code in his sketch, so you don't need to worry about the library.

The CEC firmware can be used with two displays, but displays different information on each display.  

Tom, wb6b

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