LCD serial backpacks

[flipper_md]

while it's alive..

Darrel, i've made changes as per your recommandation,
So, the skipchar label down here take care of characters not to be sent to LCD.
that works!


and then I had the *brilliant* idea to add something else...which failed.

I know we're, but not sure why.


Next I wanted to disable interrupt while I do my little LED dance at start, and send some message on the LCD.

It seems like the code will stop at > ; @ INT_ENABLE RX_INT; this seem buggy...

Do you see why I couldn't disable/enable INterrupts at start, or at that specific place?

I taught maybe i should put this in a sub routine?

; @ INT_DISABLE  RX_INT   ; Ignore input at initialisation
  
HIGH LedPort	' Some visual sign of life for the PIC
Pause 500		
LOW LedPort
pause 50

lcdout $FE,1	'LCD INIT
lcdout $FE,2
LCDOUT "LCD SERIAL - READY"
PAUSE 300  		' Timeout for LCD to settle

; @ INT_ENABLE  RX_INT  ; this seem buggy...

' * * * *   Main program starts here * * * * * * * *

loop:  
        For i = 0 to 10 	' Delay for .02 seconds (10*2mS)
	    	Pause 2   	' Use a short pause within a loop
		Next i		' instead of one long pause
        
        For i = 0 to 10 	' Delay for .02 seconds (10*2mS)
	        Pause 2   	' Use a short pause within a loop
		Next i		' instead of one long pause

skipachar:	; Will come back here if a char has to be skipped
skipchar=0	; reset the flag so next char could be displayed

display:			  	' dump the buffer to the LCD
	IF errflag Then error	' Handle error if needed
	IF index_in = index_out Then
          goto loop	' loop if nothing in buffer
          endif

	GoSub getbuf	        ' Get a character from buffer	

        if skipchar=1 then skipachar  ; with goto up there, skipping display of the last read char

        LCDOut bufchar	        ' Send the character to LCD

		IF col > 20 Then	    ' Check for end of line
			col = 1		    ' Reset LCD location
			LCDOut $fe,$c0,REP " "\20	' Clear line-2 of LCD
			LCDOut $FE,2	    ' Tell LCD to return home
		EndIF

        if ShowRTC=1 then
          LCDOut $FE,$D4,"RTC ACTIVED"
          EndIF

GoTo display	' Check for more characters in buffer



' Subroutines

;Disable				' Don't check for interrupts in this section

getbuf:					' move the next character in buffer to bufchar
  @ INT_DISABLE  RX_INT

    index_out = (index_out + 1)	' Increment index_out pointer (0 to 63)
	' Reset pointer if outside of buffer
	IF index_out > (buffer_size-1) Then index_out = 0	
	bufchar = buffer[index_out]	' Read buffer location

    if skipLCDComm>0 then
       skipLCDComm=skipLCDComm-1
       endif
    ;Routine for buffering LCD commands
    if (GrabBkLt=1) then
       ; WE have signal to watch for value for LCD backlight next
       ; LCDOut $FE,$94,"BACKLIGHT set:<",#bufchar,">"  ; for debug only

       HPWM 1,bufchar ,1250    ; Setting Pulse Mod to desired value
       	' Observe minimum FREQ for given OSC speed. 20Mhz is 1221Hz
       Low LedPort 	; Debug only	
       GrabBkLt=0   ; All is done, signal to close the loop
       skipchar=1	; to skip displaying this char in main loop
       endif
    ;Following will trigger the routine up here on the next chr received
    ; but if skip if $fe has been called 2 shots ago
    if (bufchar=20) and (skipLCDComm=0) then  ; 14h, trigger for special LCD command
       HIGH LedPort  ; Debug only
       GrabBkLt=1  ; Signal to get the value of backlight level
       skipchar=1  ; ;to skip displaying this char in main loop
       endif
    ;Prevent value of 14h to be trapped for other command, we memorize previous call of $FE (254)
    if bufchar=254  then
       skipLCDComm=2 ;
       endif
 
  @ INT_ENABLE  RX_INT
Return

[Darrel Taylor]

flipper_MD,

Are you a doctor, cause I've got this pain in my ...
Oh ... you're probably a porpoise doctor

Ummm no, I don't really see a reason for problems disabling at that point.

The closest thing to a problem I can see is that the GrabBkLt command will take over 3ms to display the LCD data ... 2ms for the command and 20+ chars at 50us delay = 1ms.

3ms by itself shouldn't be a problem, and it should only happen infrequently, but it's the closest thing to a problem I can see at first glance.

What are the symptoms?

[flipper_md]

Apparently, It will lock the PIC from receiving commands, if external data is received before it enter the main loop.

Visually, It will flash the LED, show "LCD Serial - READY", but stop there and not respond.


may I suggest Dr Pepper ?
Sugar is food for the brain

[timseven]

Yes Mr. Taylor I can't forget Joe S. as this backpack originator, I am sorry.

Well, I am almost there. I had some lines modified to the program to adapt it to my hardware. I modified:
DEFINE LCD_LINES from 4 to 2. ‘My LCD is 2X20
DEFINE OSC from 20 TO 4 ‘My 628 is 4 Mhz
DEFINE HSER_SPBRG from 32 to 25 ‘My 628 is 4 Mhz
The rest is unchanged.
When I turned it on I got the “Your text goes here” message and then over it a second later I got “Clearing display buffer” error. It’s something else that I need to change on the program to prevent the buffer to overrun? Thanks.

[Darrel Taylor]

Change TXSTA to ...

DEFINE HSER_TXSTA 24h

9600 baud at 4Mhz needs the BRGH bit set to 1 with SPBRG = 25.

[timseven]

I did the change on “DEFINE HSER_TXSTA from 20H to 25H and tested with same error. I restored all the DEFINES back to its original values (DEFINE OSC 20, DEFINE HSER_TXSTA 20H, DEFINE HSER_SPBRG 32) and used this time a 628-20 Mhz chip. I got the same error “Cleaning Display Buffer”. Any suggestion?

[Darrel Taylor]

Maybe it was just a typo, but TXSTA should have been changed to 24h, not 25h. But it probably wouldn't matter.

And when you say "and used this time a 628-20 Mhz chip"...
Do you mean that you used a 16F628 with a 20Mhz crystal and two 15-33pf capacitors?