LCD serial backpacks

[flipper_md]

well,
f-i-n-a--l-l--y went back into this and made it work, but I think it was a bad component somewhere causing problem (my regulator used to run very hot, and now it's not warm at all!)
Oh mysteries

[flipper_md]

added some code into the Instant Interrupt version, to get control of HPWM for the backlight of the LCD. Running a 16F628A @ 20Mhz
Here is the *working* version ...so far

I made it to behave like my other LCDs, so to control the backlight it wants to see code like:
$14$FF 'full power
$14$00 'off

I also upped a little program that I use to test the LCD.
http://www.flipperdesign.com/FlipLCD_control.rar

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
       ' Next set bufchar to a null char, so I wont be seen/displayed
       bufchar = 24
       Low LedPort 	; Debug only	
       GrabBkLt=0    ; All is done, signal to close the loop
       ;Re-Enable Int and go back up, to skip displaying this char
       @ INT_ENABLE  RX_INT
       goto display
       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
       ;Re-Enable Int and go back up, to skip displaying this char
       @ INT_ENABLE  RX_INT
       goto display
       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]

Ah ha, enhancements ...

Small problem though ...
getbuf: is a Subroutine.

Jumping out of a subroutine to the main loop with ...

      goto display

is going to cause some stack problems.

Try using RETURN at each of those goto's.

[flipper_md]

oh! poor stack
I will look into options to do it another way.

stack seemed to survive so far. LOL

thanks for the tip Darrel