2x16 LCD Display issues/discussion

[cmags]

Good point.. Though it took me a few minutes to figure out the point of that screen shot lol...

But I'd be trying to integrate it into this:

[dcb]

Ok, Good luck, lets us get back to LCDs here.

AndrewJ, Whats the status on your LCD?

[top_down]

dcb, it appears I have experienced an early failure of my lcd tonight. Bummer... right when you posted the things I needed to change with the injector tap and vss number!

My guino power led is on and the other led is blinking as normal, but the lcd is dark. Tried the reset button on the guino and disconnecting and reconnecting power to no avail.

It seems to have happened when I was reconnecting my ground wire, and bounced power a few times as I tightened the screw.

Anything I should check for before writing it off? Do you think they'll send me a replacement like they did for you?

Thanks for all your help and work on this project!

[dcb]

See if you can reprogram the chip first. It doesn't like bouncy power. Let me know.

[cmags]

Originally Posted by dcb;39365 (from workspace thread)

Glad the Mrs. is doing ok. It soulds like your display issues are an order of operations thing and not a hardware glitch per-se. Like you might need to bounce the power to the whole unit after you program it. Shouldn't affect in-car operation as long as you adjust your setup so the LCD is powered and connected to the duino before or at the same time the duino is powered up.

Not following you here. What I had been doing was powering the LCD from the 5V and GND pins on the 'duino (which is powered as soon as the power supply is plugged in). Not sure if its bouncy power on the LCD or if it is a timing thing, but a soft reset always temporarily resolves the issue.

I tried powering the LCD from pin 15, but it wouldn't power. My multimeter shows only ~2.5-3V on that pin (though I know it's being pulsed, I don't think its providing enough power). Haven't yet tried a separate 5V source, but I plan on trying to power both from a computer 4-pin molex - the 'duino from 12V and the LCD from 5V.

[dcb]

FYI, the latest version has a little more LCD initialization going on (v0.66), Let us know if that fixes it.

[Yoshi]

Originally Posted by dcb

FYI, the latest version has a little more LCD initialization going on (v0.66), Let us know if that fixes it.

Let me comment some...

The V0.66 init() starts...

void LCD::init(){
LcdCommandWrite(B00000010); // 4 bit operation

This sends (B0000) to DB7-4,
then sends (B0010) to DB7-4.
...

However, the HD44780 chip datasheet shows the 4 bit mode initialization is...

power on
wait for more than 15 msec
send (B0011) to DB7-4
wait for more than 4.1 msec
send (B0011) to DB7-4
wait for more than 100 usec
send (B0011) to DB7-4
send (B0010) to DB7-4 for 4 bit operation

Yoshi

[dcb]

Thanks Yoshi, I had an old lcd library I got that from. I "jiggled the handle" a little more in 0.66 and got it to come up reliably on reset. Will examine that sequence more closely for the next version.

[Yoshi]

Please refer to following 4BitLibrary.
Arduino playground - LCD4BitLibrary

Yoshi

[cmags]

I thought I had seen some minor differences in the 'guino's initialization code vs. some of the libraries on arduino.cc but I didn't get to really study the specs and codes yet, and figured there were multiple ways of doing it. Maybe the NKC LCD is more forgiving of tolerances than the one I have... I'll try v0.66 and let you know how it goes.