Electronics LCD - HD44780 compatible

I was at the electronics store just now, and saw a 2x16 LCD running off Sanyo LC7985NA which is compatible to the Hitachi HD44780 as stated here:

http://lcdriver.pointofnoreturn.org/lcds-hd44780.html

The thing is, I've soldered it up as per the instructions on the web pages from the LCD FAQ.

When I fire it up with 5V, nothing happens. I checked, double checked, triple checked all the connections all seems okay.

What's wrong?

To try my luck, I put 12V in instead of 5V, and both lines lighted up. But then nothing happens after that. (Specs rate it up to 13V)

Now I'm stumped. What is wrong?

BTW, the LCD model is SANYO DM1622, which costed me SGD9.50, which is about US$5.

Thanks in advance.

 

so do u see ne black squares at all? and what os r u running?

 

I'm running win2K.

The thing is, the black squares are displayed only with 12V, which disturbed me.

I've got the port95nt.exe, LCD Smartie, etc. as required.

But the startup test already fails.

 

if its rated up to 13 v try it at 12 v it might not like 5 tho u must do this at yr own risk (as with everything else on these forums )

 

Well, it actually says:

Logic supply voltage (Vdd-Vss) -> -0.3V to +7.0V
LCD supply voltage (Vdd - V0) -> -0.3 to +13.5V

I thought the startup will just have the odd lines flash with black squares....

Oh well, I'll give it a shot. I was thinking there's something different with this LCD. There's no pin 15 and 16. so no contrast control.

 

Pins 15 and 16 are normally backlight voltage pins - they are often separated from the other 14 when the backlight voltage is not the same as Vcc and obviously don't appear on displays without backlights. When they are not found with the other 14 pins they are normally labelled A and K (where A is pin 15 - the positive one think Anode and Kathode). Some LCD's backlights are powered from Vcc and earth (Pin's 1 and 2) - hence no need for pins 15 and 16 again.

I'm going to go have a lookat your LCD manual before I comment on the supply voltage, cheers,

r.

 

<bill+ted>
listern to this dude cheeseman he knows what hes talking about
</bill+ted>

 

Ok

http://www.nedis.com/datasheets/datasemi/D/DM1622.pdf

Page 7 - the supply volatge VDD should be 5V. The VDD - V0 rating on page 2 is referring to the contrast control of the lcd, pin 3 (V0) the LCD drive supply controls the contrast of the display and this is just saying that you can baise this between 8 volts lower (5 - - 8 = +13) and 0.3 volts higher (5 - 5.3 = -0.3V) then VDD without smoking the display...

I'm pretty sure when you wired this up the first time you had something wrong, perhap you hadn't earthed pin3 properly (max contrast) and so couldn't see any output. Now you've put 12V on pin 2 I'm pretty sure you'll have popped the controller but try rewiring it up the proper way and you never know?

Cheers,

r.

The quick test is to apply 5V to pin 2 and earth both pins 1 and 3... if you get a test signal all is still well

 

r.

 

I've done this:

pin 1 -> 5V
pin 2 -> 12V
pin 3 -> GND

Now with LCD Smartie, I'm getting flickering gibberish.

Never thought anyone would be so happy with gibberish.

Time for my flu medicine and I'll get back to this.

Need to quad-triple check my soldering.

 

Whhhaaattt? Where did you get that from?

Pin 1 - earth
Pin 2 - 5V
pin 3 - earth

the P.D. between 1 and 2 should be 5V. 7V is enough to damaged the display.

r,

p.s. Look at page 7 http://www.nedis.com/datasheets/datasemi/D/DM1622.pdf

 

Thanks Cheesman, tried the normal ground on pin 1 & 3 and 5V on pin 2. Nothing happens.

With the 12V, 7V and GND again, I still get things flashing to the tempo of what LCD smartie is scrolling. So it is still not broken yet.

I've printed out the datasheet and went through every word.

I'll put it back to 5V and double check again.

 

okay, I've desoldered all the connections checked that solder is not shorting any of the connections, resoldered them. Still nothing with 5V. No test signal.

Maybe I should try with win98...