I can not figure out an LCD issue

[mackrackit]

_XT_OSC
should be
_HS_OSC
with a resonator.

LCD_DBIT 0
change to
LCD_DBIT 4

Maybe...

Why AnyPin worked? I have no idea.

[lilimike]

Thanks for the reply Mackrackit,

Based on the datasheet _HS_OSC would be for 8 and 16 MHz but in my case I have 4 MHz.
But I gave it a try and also setting LCD_DBIT 4 but I get no timing difference with the "AnyPin" and still zilch with other setup!

I also tried FLAGS = 0 but still nothing

[malc-c]

The following works for me using an EasyPIC5 board with the LCD on PORTB, 18F4550 with 20Mhz xtal (mainly as that's what I'm using for a current project and couldn't be bothered to change the PIC !)

ASM  ; 18F2550/4550, 20mhz crystal
   __CONFIG    _CONFIG1L, _PLLDIV_5_1L & _CPUDIV_OSC1_PLL2_1L & _USBDIV_2_1L
   __CONFIG    _CONFIG1H, _FOSC_HSPLL_HS_1H
   __CONFIG    _CONFIG2L, _PWRT_ON_2L & _BOR_OFF_2L & _VREGEN_ON_2L
   __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
   __CONFIG    _CONFIG3H, _PBADEN_OFF_3H
   __CONFIG    _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
ENDASM

DEFINE OSC 48
TRISB = 0                   ' Make PORTB all outputs
CMCON = 7                   ' Disable comparator


;----[LCD definitions]------------------------------------------------------
DEFINE LCD_DREG  PORTB          ' LCD Data port
DEFINE LCD_DBIT  0              ' starting Data bit (0 or 4)
DEFINE LCD_EREG  PORTB          ' LCD Enable port
DEFINE LCD_EBIT  5              '     Enable bit  (on EasyPIC 5 LCD)
DEFINE LCD_RSREG PORTB          ' LCD Register Select port
DEFINE LCD_RSBIT 4              '     Register Select bit   (on EasyPIC 5 LCD)
DEFINE LCD_BITS  4              ' LCD bus size (4 or 8 bits)
DEFINE LCD_LINES 2              ' number of lines on LCD
DEFINE LCD_COMMANDUS 2000       ' Command delay time in us 
DEFINE LCD_DATAUS 50            ' Data delay time in us 

LCDOUT $FE,1                ' clear screen 
LCDOUT $FE,$80,"LCD Prototype MJ"  

                            ' Use $Fe,$C0 to address the second line
LCDOUT $FE,$C0,"Timer testing"  
pause 5000
LCDOUT $FE,$C0,"             "

Start:                      ' Program starts here
                            

goto start
                            
end

Using DEFINE OSC 20 I had erroneous results on the LCD, so it's obviously a timing issue with your 4MHz resonator.

[mackrackit]

When you say resonator I think of a three pin thing with built in caps, HS works for that.
If you are using a crystal then you may want to check the caps.

Forget the LCD for a bit and figure out the timing problem by blinking an LED once per second.

[lilimike]

Thanks Malc-C for the reply but I am not exactly trying to make it work...
Well yes I am trying to make it work but first I am trying to understand what is happening and what is my issue.

Mackrackit,
I am using a resonator (3 pins with caps incorporated) and double checked the datasheet and it does suggest _XT_OSC for a 4 MHz resonator.

I followed your suggestion and I put a LED with puse 1000 and also it is taking 2 secs to blink. Now, I set DEFINE OSC 4 instead of 8 which brought down to 1 sec as I expected so I know that if i am using a 4 MHz crystal, I should be having DEFINE OSC 4. I could be wrong but I think this part is clear to me.

So my questions are changing a bit and now I end up with:

1 - Why does LCD_AnyPin only works with DEFINE OSC 8 although I have a 4 MHz crystal ?

2 - Why the standard way for LCD is not working whisle LCD_AnyPin did even at 8 ?

When I find out, I will never forget it!

Mike

[lilimike]

after reading over the thread I just saw this:

Using DEFINE OSC 20 I had erroneous results on the LCD, so it's obviously a timing issue with your 4MHz resonator

I took out my resonator and used the chips' internal oscillator but I get the same results so this rules out the resonator I was using.

When using LCD_AnyPin it works with 8 MHz but the timing is doubled, if I set to 4 MHz the timing is is ok and LCD is blank.

Furthermore using standard settings for LCD does not work at all settings for OSC.

Help!

[mackrackit]

The only suggestion I have now is to play with these lines.

DEFINE LCD_COMMANDUS 2000       ' Command delay time in us 
DEFINE LCD_DATAUS 50            ' Data delay time in us

Use the 4 MHZ OSC
DEFINE OSC 4

[malc-c]

after reading over the thread I just saw this:


I took out my resonator and used the chips' internal oscillator but I get the same results so this rules out the resonator I was using.

When using LCD_AnyPin it works with 8 MHz but the timing is doubled, if I set to 4 MHz the timing is is ok and LCD is blank.

Furthermore using standard settings for LCD does not work at all settings for OSC.

Help!

Mike,

That's why I included the statement. With a 20Mhz xtal and setting the define to 20 I got random parts of the text displayed. When I set the define to 48 it worked - why I don't know (I'm still a newb to a degree My guess is that the value is divided internally somewhere to set the timing, which is why in your case setting it to 8 works with a 4Mhz xtal

[Acetronics2]

The following works for me using an EasyPIC5 board with the LCD on PORTB, .

Hi, Lili

Me too with a 16F628 @ 8Mhz ... same board.
"LCD on Anypin" mods implemented ... but not used here.

may be the missing LCD Settling time @beginning of the program ???

Alain

[lilimike]

Dave,
I have tried
DEFINE LCD_COMMANDUS 1000 and 4000
DEFINE LCD_DATAUS 25 and 100
with no aparent changes.

Malcom,
The display does work at 8 MHz with a 4 MHz resonator but the chip's timing is doubled and that is what I am trying to figure out. so a PAUSE 1000 will last 2 seconds instead of 1 second. The timing for this project is important because I want to build an ultrasound distance mesurement and so I have to time the echo received after sending an output burst of 40 KHz. I think I am far from my goal but I can't get started with the fun part untill I have figured out my issue with the timing problem.

Alain,
What did you mean by this?

may be the missing LCD Settling time @beginning of the program ???

For the record this is my hardware configuration and with an oscilloscope I see the 5V as pure DC 5.12V

[lilimike]

Ok so here is a positive update...

I had removed my resonator last night to rule it out and got the same issue with the chip's internal oscilator. Today I just put back the resonator and set _XT_OSC again and now it is working fine at 4 MHz.

Furthermore...! if I remove the LCD_Anypin, it is now still working with the standard version.

So please correct me if I am wrong but I am working with a breadboard and I suspect when I had the resonator at first, there was a bad contact with one of its pin!

Thanks to all for your responses, it kept me going.

Mike

[mackrackit]

Yup
A bad connection will make all kinds of strange things happen.