Bah! Too much work. Here's the LCD connections.

LCD Pins:
Pin 1. Ground (VSS)
Pin 2. 5V (VDD)
Pin 3. 1K resistor to ground (VSS).
Pin 4. RD2 and also a 10K pullup resistor
Pin 5. Ground (VSS)
Pin 6. RD3
Pin 7. RB0
Pin 8. RB1
Pin 9. RB2
Pin 10. RB3
Pin 11. RB4
Pin 12. RB5
Pin 13. RB6
Pin 14. RB7
Pin 15. 5V (VDD) (Backlight)
Pin 16. Ground (VSS) (Backlight)

I determined the resistor value for Pin 3 by first putting a 10K potentiometer in using one leg and the wiper from pin 3 to ground, adjusting it till the display looked good, removing it and measuring the resistance and putting that value of resistor back in place of the pot. LCDs vary from model to model. If you just put in the resistor there's a good chance you'll end up with maladjusted contrast and have a "blank display".

Silly questions:
You ARE using a 4MHz crystal as the schematic shows, right? If you aren't, that would explain the the blinking LED program working but the LCD not working. The LCD delay durations depend on the PIC running at that 4MHz clock speed (or lower, but not higher). If you put (for instance) a 20MHz crystal on the PIC the LCD is not gonna work until you change either the code or the crystal.

Is your MCLR pulled up properly? If not the chip could possibly be doing something weird like restarting over and over, giving the illusion that the blinky program is actually running when it's really not. Try making some changes to the blinky prog and see if it responds correctly.

Got enough juice? Not enough power can cause LCDs to not work properly. I found this one out the hard way a couple times. Backlight seemed to be working, but couldn't get the display to work right. Got better power to it and it took right off. It had been working all along but I couldn't see it.

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Futz's Microcontrollers & Robotics
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Today I tested the new LCD with my programme, it works. I'm so happy, testing for a long time, today success. Now I know the big problem is caused by the LCD failure. Thanks to all who give suggestion, advise and encouragement. Eric, Eng1, mvs sarma, Pommie, blueroomelectronics and futz, THANK YOU VERY MUCH!!

Erm... Now I've one more question to ask.... If the LCD feel a bit warm is consider burnt?

Today I tested the new LCD can work properly, but I think through my careless, I connected wrongly that caused the cicuit short. After that the LCD cannot function anymore and feel slightly warm. Is LCD burnt?? (I'm so stupid )

 

Hey Smileguitar,

Are you telling about the old display that went faulty or,god forbid, is it second time failure?

Generally the voltage pattern at pins 1,2 and 16,15, they are symmetrical. even if pin3 goes to pin 14, it could be imagined as high or low input on D7-this also should not matter. So reverse connection may not cause failure of display and when normalcy restored,it should start working. But, on the other hand if connection pulled out while the supply is ON and display working, this type of failure is anticipated , as far as i could analyze.

__________________
Regards,
Sarma.

 

LCDs are really easy to kill, if you ever reverse power & gnd it's ususually bye bye.

__________________
Bill
Smart Kits build Smart People
http://www.blueroomelectronics.com

 

I'm telling about the new display. I'm not connect wrongly at LCD pins, but in MCLR pin of PIC. I connect a push button in pin1 of PIC with a diode, resistor and capacitor. Unfortunately, I made it short circuit. After this, my new LCD is not function stable. Is LCD burnt again? or.....???

 

i was talking about the reversal of the entire 16 pin connector of LCD display with spl ref to JHD162A model. Generally voltage reversal in solidstate circuits and digital circuits,kills many ICs. memories more instantaneously.

however Smileguitar confirms that it is case of mishandling pin1 of the 16F877 (MCLR), i suppose. That might not cause such serious damage to LCD display, i hope, as there is no Vpp at a working board.

__________________
Regards,
Sarma.

 

Hopefully. Thanks in advance. I'll double check it....

 

I've successfully displayed character in LCD, now going to do my next step of my project. Thanks all guys !!!

 

[quote=ericgibbs]hi,
Tried running your code on my simulator, it looks as though the LCD controller is the Hitachi HD44780.
All I get on the LCD is '23' on the second line.
Where are the RS and R/W lines connected?

I dont see any reference to these control lines in your program.

Also you have enclosed your web link in 'brackets' I cannot call it!.
EDIT:
Managed to get the gif, see that RS is on RD2 and R/W is low.[/QUOTE

sir i want jhd162a lcd dtasheet,cn u pls suggest wre i cn get tat... i dint get tat anywhere.....

 

the JHD162A is compatible. Nothing to worry. i use it

__________________
Regards,
Sarma.