Problem With 20x4 LCD on Due?


i have 3 i2c devices on due project.  first i2c i/f (wire) connected fpga, running i2c @ 2mhz.  works perfectly.  second i2c i/f (wire1) connected i2c eerom, , 1 of generic 20x4 lcds.  eerom works itself.  lcd works when connected promini.  if i2c device scan, both devices found @ correct addresses (0x27 lcd, 0x50 eerom).  but, after call lcd init() method, eerom stops working, , have tet lcd work @ on due.  unable lcd work itself, using same simple test program works on promini.

to deal voltage difference, lcd connected due via 330 ohm series resistor, , 5.1k pullup +3.3v on due i2c pins.  same interface approach works other 5v peripherals, including fpga.

are there known problems 20x4 lcd causing problem?  has here ever run 1 of these lcds second device on i2c bus?  uses same philips i2c parallel chip every other similar lcd i've ever used.  hard believe philips screw i2c, given invented it.  and, indeed, *seems* work, device scan works every time.

regards,
ray l.

have tried using lcd due , ordinary 4bit mode connection mode?
i don't know exclude or prove i2c @ fault, running 20x4 lcd due , supply 5v power supply connecting io pins directly lcd , works fine.

regards


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