WEll, I have 2 4x20 character LCD screens from ywrobot with the LCM1602 IIC V1 adapter boards on them..
What's strange? well, I've had them working a few months ago, then life happened and I came back to the project.. NO WAY to interface them to either my Mega, Uno, or Leo
I found this I2C scanner from Rob Tillart MultiSpeed I2C Scanner - 50,100,200,400 KHz. - Libraries - Arduino Forum and thought it was great.. So I run it, and it freezes if I have the SDA line connected..
So I have some realtime clocks on I2C and decide to try with them,.. they work perfectly.. They also have power and data throughput lines, so I connect those to my LCD and it suddenly works.. will not work without the RTC though
What gives? pullup resistors missing somewhere? Why did it work before then?