LCD not working (in known working circuit)?? - Electronic Circuits Projects Diagrams Free

Marks256 · 21st June 2009, 04:35 AM

I just bought a 20x4 LCD on ebay (1x LCD 20x4 HD44780 Blue Backlight headers *USA *fcbusa) advertised to use an HD44780. I just recently got around to testing to see it work, and it doesn't! I placed it in a circuit that i know works, and even tested it with another 20x4 HD44780 LCD, and the circuit works great. But the new lcd i bought just displays gibberish!

I'm really not sure what the problem could be? Does anyone have an explanation for why 2 HD44780's wouldn't work in the same circuit? Maybe i'm over looking something...

nike6 · 21st June 2009, 04:58 AM

that site looks a little fraudulent.

Marks256 · 21st June 2009, 05:02 AM

here is their ebay page i actually bought it from.

1x LCD 20x4 HD44780 Blue Backlight headers *USA *fcbusa - eBay (item 150326760448 end time Jul-13-09 13:27:23 PDT)

Quite good feeback.

nike6 · 21st June 2009, 06:00 AM

2x SMD MICROCHIP PIC 18F4520 and 2x TQFP to DIP PCB

1. price $88 (88 dollars). sort of supernatural 10x price. for a reason?

2. using graphics which have the logo from a chinese company. under license? are they an official franchise of sure electronics?

3. distorted America flags. it just does not look nice.

4. same items as sure electronics but 200% price. normal commission is 20% to 50%.

I do not complain but they won't atttract many customers having such unprofessional appearance.

100x 3mm 4 colors RWBG Ultra Bright LEDs *fcbusa
very fraudulent:

Quote:

Do Not Purchase... Item Description Not Complete... ... Your Homeland Electronics Store... ... FCB Electronics...... Ann Arbor, Michigan... ... All FCB items ship from USA.... Fastest shipment to all of North America and Europe... ( See My Feedback "Fastest Shipper" )...... 100 pcs 5mm Four (4) Colors LED... Red , White, Blue &...

Hybrid of PIC18F4520 Dem2PLUS and Low Power Demo *USA
819.99 dollars

Pommie · 21st June 2009, 06:11 AM

Some of the more modern chips are much faster than the original Hitachi chip and so they will work with shorter delays in the initialisation and write routines. If your new display requires the original timing parameters then it may work if you increase the delays in your code.

Mike.

nike6 · 21st June 2009, 06:26 AM

if this stuff works you have good luck

Marks256 · 21st June 2009, 04:04 PM

Quote:

Originally Posted by Pommie

Some of the more modern chips are much faster than the original Hitachi chip and so they will work with shorter delays in the initialisation and write routines. If your new display requires the original timing parameters then it may work if you increase the delays in your code.

Mike.

Thanks. I'll increase the delays and see if that works.

Marks256 · 22nd June 2009, 04:21 AM

Well i solved the problem purely by accident...

I needed to use the interrupt pins (atmega16), so i moved the LCD from PORTD to PORTC, and the LCD magically worked! Turns out on my development board i had the RX and TX jumpers connected to the MAX232 and that was somehow interfering with the new lcd, but not the old lcd. Very simple mistake

It's working like a champ now

Thanks all for the help! it was greatly appreciated.

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21st June 2009, 04:35 AM	#1
Marks256	LCD not working (in known working circuit)?? I just bought a 20x4 LCD on ebay (1x LCD 20x4 HD44780 Blue Backlight headers USA fcbusa) advertised to use an HD44780. I just recently got around to testing to see it work, and it doesn't! I placed it in a circuit that i know works, and even tested it with another 20x4 HD44780 LCD, and the circuit works great. But the new lcd i bought just displays gibberish! I'm really not sure what the problem could be? Does anyone have an explanation for why 2 HD44780's wouldn't work in the same circuit? Maybe i'm over looking something... __________________ There is no "I" in "team", unless Apple makes it... Then it would be iTeam.

21st June 2009, 04:58 AM	#2
nike6	that site looks a little fraudulent.

21st June 2009, 05:02 AM	#3
Marks256	here is their ebay page i actually bought it from. 1x LCD 20x4 HD44780 Blue Backlight headers USA fcbusa - eBay (item 150326760448 end time Jul-13-09 13:27:23 PDT) Quite good feeback. __________________ There is no "I" in "team", unless Apple makes it... Then it would be iTeam.

21st June 2009, 06:11 AM	#5
Pommie	Some of the more modern chips are much faster than the original Hitachi chip and so they will work with shorter delays in the initialisation and write routines. If your new display requires the original timing parameters then it may work if you increase the delays in your code. Mike. Last edited by Pommie; 21st June 2009 at 06:14 AM. Reason: clarification.

21st June 2009, 06:26 AM	#6
nike6	if this stuff works you have good luck

22nd June 2009, 04:21 AM	#8
Marks256	Well i solved the problem purely by accident... I needed to use the interrupt pins (atmega16), so i moved the LCD from PORTD to PORTC, and the LCD magically worked! Turns out on my development board i had the RX and TX jumpers connected to the MAX232 and that was somehow interfering with the new lcd, but not the old lcd. Very simple mistake It's working like a champ now Thanks all for the help! it was greatly appreciated. __________________ There is no "I" in "team", unless Apple makes it... Then it would be iTeam.