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[Reply #45 on:]

Maybe it really does need to be initialized and newhaven doesn't know because they have never tried?

I doubt it.

I have tried no less than 50 - 100 different lcds. All of them can be initialized by the standard HD44780 routine. Some can be initialized by alternative routines. I think it is highly unlikely that NH will provide a lcd that cannot be initialized by the HD44780 routine.

BTW, the LiquidCrystal initialization routine is not in compliance with the HD44780 datasheet.

[Reply #46 on:]

Maybe it really does need to be initialized and newhaven doesn't know because they have never tried?

I forgot to comment about this.

I think you missed the point.  All of the controllers need some sort of initialization but our test that looks for a row of blocks relies on an uninitialized or more accurately an improperly initialized controller.

We know that a two row display using an HD44780 type controller will typically display a single row of blocks when it is not properly initialized.  We can guarantee that it will not be properly initialized by simply applying power without also sending it any instructions.  So, if you power up such a display and you see a row of blocks then it may be good.  If you power up such a display and you do not see a row of blocks then it probably is bad.  Since you need the backlight in order to see some of the displays we also suggest powering it as well.

The above test works because the internal reset circuit of an HD44780 type controller configures that controller to deal with a 1-line display.  Since the vast majority of displays are 2-line displays (including most of the ones that have a single row of 16 characters) they are automatically improperly initialized and therefore display the blocks.  It is quite possible that the internal reset circuit of the controller on the NewHaven display correctly initializes the controller for a 2-line display in which case the row of blocks may very well not show up.  That is why we need more information from them.

Don

[Reply #47 on:]

BTW, the LiquidCrystal initialization routine is not in compliance with the HD44780 datasheet.

Well well - we agree on something!!!

I assume you are talking about the step that turns the display on when it should be turned off.

When Limor (LadyAda) first published her updated library, and before it was incorporated into the Arduino distribution, I pointed out the discrepancy to her and the response was essentially that 'it works so why change it'.  AARRGGHH

[Edit]: Or maybe you are talking about accounting for the possibility that the controller clock may be running a lot slower than the nominal value when determining the time delays.  I mentioned that to her as well.

Don

[Reply #48 on:]

Hello! I am writing a follow up on this project. I did after all hook up my UNO and voila! the LCD display works! So it is indeed a big factor that it MUST be a 5V controller for this Display.

But from your earlier photo, you do have an UNO.
So while the UNO can't be used in the final project/product it could be used to verify if the LCD is working or not.
It would only take a few minutes to hook up the uno to the LCD and run the
"hellworld" LiquidCrystal library example sketch.
This would verify that the LCD is working.

I know this sounds strange but if I got caught using anything other than what I was given I would have gotten in trouble (alot of trouble).... I did this one the sly.

I did some research and found the NHD-C0220AA-FSW-FTW which is 3.3V and bought it. I hooked that one up to my original circuit (using the Pro-Mini) and voila again! It works like a charm on the 3.3V pro-mini.

Now, I have the display initialized (yay) and I am indeed writing an 'N' (see my code on page 1). I now have to write some more code and/or experiment with the code that is in the LiquidCrystal library.

Thank you all so much for all your help on this! I love this forum!

Cheers!   

[Reply #49 on:]

Yay!

[Reply #50 on:]

Hello! I am writing a follow up on this project. I did after all hook up my UNO and voila! the LCD display works!

Please tell us whether or not you get the row of blocks when only using the power and backlight.  Do this for each of the displays when each is operating from the appropriate power supply.

Also - If you have the opportunity, would you also test the 5 volt display operating from 3.3 volts using a negative voltage for the contrast.  You can obtain this voltage using a small battery.  Just disconnect the lower end of the potentiometer from GND and connect it to the (-) terminal of the battery.  Connect the (+) terminal of the battery to GND.  This will allow you to vary the contrast from positive, through 0v, to negative.

Don

[Reply #51 on:]

Hello! I am writing a follow up on this project. I did after all hook up my UNO and voila! the LCD display works! ...

I did some research and found the NHD-C0220AA-FSW-FTW which is 3.3V and bought it. I hooked that one up to my original circuit (using the Pro-Mini) and voila again!

Micracles do happen from time to time.

This whole store reminds me of that sparkfun white-on-blue lcd that works under the sun without backlighting - I am still waiting to see a picture of it,