I can not figure out an LCD issue

[lilimike]

Hi,
I have been trying to figure this out for a couple of days now but no luck.

I am using 16F627A
At first I was using the internal osc with _INTOSC_OSC_NOCLKOUT and I was using the commented section bellow (Daryl's LCD_AnyPin) and I had DEFINE OSC 8 as any other value gave me a blank LCD.
This setup displayed information well on the LCD but at the bottom of my code I have a PAUSE 5000 which I expected the second line to go blank after 5 seconds however it went blank after about 10 secs.

I then added an 4 MHz external resonator, changed the fuse as bellow and tried different values for OSC but same results.

So I restored my pbppic14.lib to its original value commented the LCD_AnyPin section and added the standard way as bellow but now I am just getting question marks on the LCD.

So I guess I have 2 questions;
1 -Why did I get the wrong timing in my first setup?
2 - Why the standard way for LCD is not working whisle LCD_AnyPin did?

If anyone can make my day, that would be great.

Thanks

Mike

@ __config _XT_OSC & _WDT_OFF & _MCLRE_ON & _LVP_OFF & _CP_OFF

DEFINE OSC 4
TRISB = 0                   ' Make PORTB all outputs
CMCON = 7                   ' Disable comparator

'- - - - LCD_AnyPin.pbp - - - - - - - - - - - - - - - - - -
'LCD_DB4   VAR PORTB.0       ' Set port for 4 bits bus
'LCD_DB5   VAR PORTB.1
'LCD_DB6   VAR PORTB.2
'LCD_DB7   VAR PORTB.3
'LCD_RS    VAR PORTB.5       ' Set RS bit port
'LCD_E     VAR PORTB.4       ' Set Enable bit port
'LCD_Lines     CON 2         ' # of Lines on LCD,  1 or 2 (Note: use 2 for 4 lines)
'LCD_DATAUS    CON 50        ' Data delay time in us 
'LCD_COMMANDUS CON 2000      ' Command delay time in us 
'INCLUDE "LCD_AnyPin.pbp"    ' Must go after LCD initialization 

'- - - - Standard - - - - - - - - - - - - - - - - - -
define LCD_DREG PORTB       ' Define LCD Data Port
Define LCD_DBIT 0           ' Set starting data bit (0 or 4)
Define LCD_RSREG PORTB      ' Set Register Select port
Define LCD_RSBIT 5          ' Set RS bit
Define LCD_EREG PORTB       ' Set Enable port
Define LCD_EBIT 4           ' Set E bit
Define LCD_BITS 4           ' Set bus size 
Define LCD_LINES 2          ' Set number of lines on LCD
Define LCD_COMMANDUS 2000   ' Set command delay time
Define LCD_DATAUS 50        ' Set data delay time

'- - - - start of program - - - - - - - - - - - - - - - - - -
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

[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

[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