Infact that is exactly the project I used. I can get the I2C address and I can get the backlight to come on and off. But I cannot get any characters displayed or visible.
On the backside there is a blue potentiometer: use a small screwdriver to change the brightness.
Its possible for you to upload some pictures? Double checked D0 / D1?
I’m having very similar problem. On max brightness I can barely see text on my 20x4 LCD.
I suspect it’s because it needs 5v and Photon provides only 3.3v.
Do you know is where a way to make it work, or shall I use something with more power? Thanks.
Not sure how to check an exact model, I’ll copy-paste it from an ebay description:
Part Number: ERM2004DNS-1-4832
Display Type: FFSTN-LCD Black
Power Supply(Typ): 5V
Looks like it’s actually 5v version, I’ve realized there are different versions of it. I’ll try to order 3.3v version.