I would remove the 5v pullups from the LCD backpack, the Raduino still has 3.3v pullups on those lines.
A 3.3v high into the PCF8574T chip on the LCD backpack board seems to work fine.
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/g/BITX20/message/39966?
On Tue, Jun 5, 2018 at 10:07 am, Tim Gorman wrote:
You can't just connect D4 and D5 to the SDA/SCL leads.
You need an I2C adapter added to the back of the lcd.
this is an example:
www.ebay.com/itm/Serial-IIC-I2C-Adapter-1602-1604-2002-LCD-Backpack-Arduino-FAST-SHIP-US-SELLER/171036006949?hash=item27d28a5a25:g:vNIAAOSwMmBVnc7K:sc:USPSFirstClass!66609!US!-1
