Digital touch Screen Combination lock

[astanapane]

Dear all,

i need your help once again. I would like to replace the physical matrix 3x4keypad combination lock with a Digital touch screen display.

I have for couple of years a display from 4D systems, 32DT which is a nice touch display. So i though i could add the digital 3x4 matrix keypad and retrieve the information for every key, via serial port and using this information, i could manage to make a simple combination code.



The following is the information recieved for every key pressed. There is also 07Hex in front of all those numbers.

As i read the datasheet of the Screen the actual value every number sent.....for example for the number 1 is 31hex.

num1    data  "0D0000313B" ; this is number 1
num2 	data  "0D00003238" ; this is number 2
num3    data  "0D00003339" ; this is number 3
num4    data  "0D0000343E" ; this is number 4
num5    data  "0D0000353F" ; this is number 5
num6    Data  "0D0000363C" ; this is number 6
num7    Data  "0D0000373D" ; this is number 7
num8    Data  "0D00003832" ; this is number 8
num9    data  "0D00003933" ; this is number 9
num10   data  "0D00002A20" ; this is number *
num11   data  "0D0000303A" ; this is number 0
num12   data  "0D00000802" ; this is number #

In the beggining i wanted to store those values everytime the key is pressed. My knowledge in programming is limitted so i though that if i want to use the digital 3x4 touch display i need to find an other way.

Please check the following program....it works for the first couple of 30 seconds. But then somthing goes wrong, maybe in the loops or in the gosub instructions, and program messed up and freeze.

Could anyone help me please?

'*  Notes   : This is a codelock based on the following components    *
'*          : PIC18F26K22 or PIC18F46K22 @ 64Mhz                      *
'*          : 4D Systems ULCD 32DT diablo                             *
'**********************************************************************     

'*********************************************************************************
@ ERRORLEVEL -306 ; this command prevents the compiler to give you a notice of   *
                  ; crossing page boundary - make sure bits are set              *
'********************************************************************************* 
 
  #CONFIG   ;  The PBP configuration for the PIC18F26K22 is:
;    CONFIG FOSC     = RCIO6	    ; External RC oscillator
     CONFIG FOSC     = HSHP	        ; HS oscillator (high power > 16 MHz)
     

;*---------------------------------4x PLL ENABLE--------------------------------------*|
;*  4X PLL Enable                                                                     *|
;*    CONFIG PLLCFG  = OFF	        ;Oscillator used directly                         *|
    CONFIG PLLCFG    = ON	        ;Oscillator multiplied by 4                       *|
;*------------------------------------------------------------------------------------*|
;
;  Primary clock enable bit
;    CONFIG PRICLKEN = OFF	        ;Primary clock can be disabled by software
    CONFIG PRICLKEN  = ON	        ;Primary clock enabled
;
;  Fail-Safe Clock Monitor Enable bit
    CONFIG FCMEN     = OFF	        ;Fail-Safe Clock Monitor disabled
;    CONFIG FCMEN    = ON	        ;Fail-Safe Clock Monitor enabled
;
;  Internal/External Oscillator Switchover bit
    CONFIG IESO      = OFF	        ;Oscillator Switchover mode disabled
;    CONFIG IESO     = ON	        ;Oscillator Switchover mode enabled
    
    CONFIG  BOREN    = SBORDIS      ; Brown-out Reset enabled in hardware only (SBOREN is disabled)
    
;*--------------------------------------------------------------------------------------------------------;|
    CONFIG  WDTEN    = ON           ; WDT is always enabled. SWDTEN bit has no effect                     ;|
    CONFIG  WDTPS    = 32768        ; 1:32768 ---> HERE enable the watchdog timer with a 1:32768 postscale;|
;*--------------------------------------------------------------------------------------------------------;|
    
    CONFIG  PWRTEN   = ON
    CONFIG  HFOFST   = ON           ; HFINTOSC output and ready status are not delayed by the oscillator stable status
    CONFIG  MCLRE    = EXTMCLR      ; MCLR pin enabled, RE3 input pin disabled
    CONFIG  LVP      = OFF          ; Single-Supply ICSP disabled
    CONFIG  XINST    = OFF          ; Instruction set extension and Indexed Addressing mode disabled (Legacy mode)
    CONFIG  DEBUG    = OFF          ; Disabled

  #ENDCONFIG
  
;*---------------------------------------------------------------------------------------------------------|
;*---------------------------------------------------------------------------------------------------------|

define  OSC 64

        INCLUDE "modedefs.bas"
        INCLUDE"ALLDIGITAL.pbp"

OSCCON    = %01110000   ; 64Mhz
OSCTUNE.6 = 1           ; Enable 4x PLL

while ! osccon2.7 :WEND ; to make sure the pll has stabilised before you run any other code

'-------------------------------------------------------------------------------------------------------------------------------------------------------------

TRISA = %00000000   'use TRISA to specify which pin is (1 = input) and which (0 = output)  (ALL pins are output)
TRISB = %00000000   'use TRISB to specify which pin is (1 = input) and which (0 = output)  (RB7 PORTB.7 is the RX input pin of the EUART, the rest are output)
TRISC = %10000000   'use TRISC to specify which pin is (1 = input) and which (0 = output)  (RC7 PORTC.7 is the RX input pin of the EUART, the rest are output)
                    'in PORTC the RC3 attached is an LED. 

'------------------------------------------------------------------------|
'--------------------------- TRIS A B C ---------------------------------|
'------------------------------------------------------------------------|
' PORTA.7  PORTA.6  PORTA.5  PORTA.4  PORTA.3  PORTA.2  PORTA.1  PORTA.0 |
'  bit7     bit6     bit5     bit4     bit3     bit2     bit1     bit0   |
'   0        0        0        0        0        0        0        0     |
'------------------------------------------------------------------------|
'------------------------------------------------------------------------|
' PORTB.7  PORTB.6  PORTB.5  PORTB.4  PORTB.3  PORTB.2  PORTB.1  PORTB.0 |
'  bit7     bit6     bit5     bit4     bit3     bit2     bit1     bit0   |
'   0        0        0        0        0        0        0        0     |
'------------------------------------------------------------------------|
'------------------------------------------------------------------------|
' PORTC.7  PORTC.6  PORTC.5  PORTC.4  PORTC.3  PORTC.2  PORTC.1  PORTC.0 |
'  bit7     bit6     bit5     bit4     bit3     bit2     bit1     bit0   |
'   1        0        0        0        0        0        0        0     |
'------------------------------------------------------------------------|

'------------------------------------------------------------------------|
'----------------------- At start all PORTS LOW -------------------------|
'------------------------------------------------------------------------|
PORTA = 0            'make low all ports at A range                      |
PORTB = 0            'make low all ports at B range                      |
PORTC = 0            'make low all ports at C range                      |
PORTE = 0            'make low all ports at E range                      |
'------------------------------------------------------------------------|

'------------------------------------------------------------------------|
'-------------------------- COMPARATORS OFF -----------------------------|
'------------------------------------------------------------------------|
CM1CON0.7 = 0 'Disable comparator1                                       |
CM2CON0.7 = 0 'Disable comparator2                                       |
'------------------------------------------------------------------------|

'*-----------------------------------------------------------------------------|
'*                        |  --------------------- |                           |
'*----------------------- | EUART 1 Configuration  | --------------------------|
'*                        |  --------------------- |                           |
'*-----------------------------------------------------------------------------|

        DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
        DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
        DEFINE HSER_CLROERR 1 ' Clear overflow automatically
        DEFINE HSER_SPBRG 138 ' 115200 Baud @ 64MHz, -0.08%
        SPBRGH = 0
        BAUDCON.3 = 1         ' Enable 16 bit baudrate generator

'*-----------------------------------------------------------------------------|
'*                        |  --------------------- |                           |
'*----------------------- | EUART 2 Configuration  | --------------------------|
'*                        |  --------------------- |                           |
'*-----------------------------------------------------------------------------|

        DEFINE HSER2_RCSTA 90h ' Enable serial port & continuous receive
        DEFINE HSER2_TXSTA 24h ' Enable transmit, BRGH = 1
        DEFINE HSER2_CLROERR 1 ' Clear overflow automatically
        DEFINE HSER2_SPBRG 160 ' 38400 Baud @ 64MHz, -0.08%
        SPBRGH2 = 1
        BAUDCON2.3 = 1         ' Enable 16 bit baudrate generator

'*-----------------------------------------------------------------------------|
'*-----------------------------------------------------------------------------|

Timeout         CON 2000
DATAIN          var byte[5]

ResetLCD        var PORTC.2
RED             var PORTC.3
BLUE            var PORTC.4  

i               var byte

' -----[ EEPROM Data ]-----------------------------------------------------

i just made a note of those numbers.

;num1    data  "0D0000313B" ; this is number 1
;num2 	data  "0D00003238" ; this is number 2
;num3    data  "0D00003339" ; this is number 3
;num4    data  "0D0000343E" ; this is number 4
;num5    data  "0D0000353F" ; this is number 5
;num6    Data  "0D0000363C" ; this is number 6
;num7    Data  "0D0000373D" ; this is number 7
;num8    Data  "0D00003832" ; this is number 8
;num9    data  "0D00003933" ; this is number 9
;num10   data  "0D00002A20" ; this is number *
;num11   data  "0D0000303A" ; this is number 0
;num12   data  "0D00000802" ; this is number #

;------------------------------------------------------------------------------|
;                           [LCD hold on reset]                                |
;------------------------------------------------------------------------------|
high resetlcd 
pause 500
low resetlcd
' -----------------------------------------------------------------------------|  
'                            [ pic power led ]                                 |
'------------------------------------------------------------------------------|
for i = 1 to 5 
high RED : pause 50
low red : pause 50
next i

high red
'------------------------------------------------------------------------------|          

Start:

HSERIN [WAIT($07), str datain\5]

if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$31  and  datain[4] =$3B then
gosub reset
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$32  and  datain[4] =$38 then
gosub flash2
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$33  and  datain[4] =$39 then
gosub reset
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$34  and  datain[4] =$3E then
gosub flash4
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$35  and  datain[4] =$3F then
gosub reset
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$36  and  datain[4] =$3C then
gosub reset
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$37  and  datain[4] =$3D then
gosub flash7
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$38  and  datain[4] =$32 then
gosub flash8
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$39  and  datain[4] =$33 then
gosub reset
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$2A  and  datain[4] =$20 then
gosub reset
        endif        
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$30  and  datain[4] =$3A then
gosub reset
        endif
if datain[0] = $0D and  datain[1] =$00 and  datain[2] =$00  and  datain[3] =$08  and  datain[4] =$02 then
gosub flash12
        endif
     goto start

flash:
hserout2 [str datain\5]
high blue
pause 50
low blue
    return

flash2:
hserout2 [str datain\5]
high blue
pause 50
low blue
high portb.0
gosub chkey
    return
    
flash7:
hserout2 [str datain\5]
high blue
pause 50
low blue
high portb.1
gosub chkey
    return
    
flash8:
hserout2 [str datain\5]
high blue
pause 50
low blue
high portb.2
gosub chkey
    return
    
flash4:
hserout2 [str datain\5]
high blue
pause 50
low blue
high portb.3
gosub chkey
    return
    
flash12:
hserout2 [str datain\5]
high blue
pause 50
low blue
high portb.4
gosub chkey
    return
    
chkey:
if  portb.0 = 1 and portb.1 = 0 and portb.2 = 0 and portb.3 = 0 and portb.4 = 0 then start
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 0 and portb.3 = 0 and portb.4 = 0 then start
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 0 and portb.4 = 0 then start
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 1 and portb.4 = 0 then start   
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 1 and portb.4 = 1 then pwok   


if  portb.0 = 0 and portb.1 = 0 and portb.2 = 0 and portb.3 = 0 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 0 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 0 and portb.3 = 1 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 0 and portb.3 = 1 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 1 and portb.3 = 0 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 1 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 1 and portb.3 = 1 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 0 and portb.2 = 1 and portb.3 = 1 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 0 and portb.3 = 0 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 0 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 0 and portb.3 = 1 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 0 and portb.3 = 1 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 1 and portb.3 = 0 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 1 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 1 and portb.3 = 1 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 0 and portb.1 = 1 and portb.2 = 1 and portb.3 = 1 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 0 and portb.2 = 0 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 0 and portb.2 = 0 and portb.3 = 1 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 0 and portb.2 = 0 and portb.3 = 1 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 0 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 0 and portb.3 = 1 and portb.4 = 0 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 0 and portb.3 = 1 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 0 and portb.4 = 1 then 
gosub reset
            endif
if  portb.0 = 1 and portb.1 = 0 and portb.2 = 1 and portb.3 = 0 and portb.4 = 0 then 
gosub reset
           endif
      return

reset:
high blue
pause 50
low blue
low portb.0
low portb.1
low portb.2
low portb.3
low portb.4
return

pwok:
low portb.0
low portb.1
low portb.2
low portb.3
low portb.4
high portb.5
pause 2000
low portb.5

return

[HenrikOlsson]

Please check the following program....it works for the first couple of 30 seconds. But then somthing goes wrong, maybe in the loops or in the gosub instructions, and program messed up and freeze.

Yes indeed. One problem is that you are potentially jumping out of a subroutine without somehow ending up at a matching RETURN.

Specifically: You're GOSUBing chkey but then, if any of the first couple of convoluted logic statement are found true you're going straight back to start, leaving a return address on stack. Once that has happened enough times (depending on PIC family) the program will crash.

Next thing, which might not be part of the actual issue but makes your code "clumsy"...
You're using the five low bits of PORTB as inputs but why on earth are you NOT reading those bits into a BYTE variable and comparing the resulating value against your different qualifiers?

value VAR BYTE
value = PORTB & 00011111    ' Read 5 low bits of PORTB into value

Now the variable value will contain a value between 0 and 31 covering all possible combinations of the 5 bits.
If value is 31 you want pwok
if value is 1,3,7, or 15 you want start
if value is anything else you want reset

That is what ALL those 80 something lines of IF this AND this AND this THEN that type of code in the chkey subroutine does...

/Henrik.

EDIT: One more thing: You're clearly reading PORTB which must mean you're using those five low bits as inputs, yet, at the top of the program you have TRISB = %00000000 which makes all of PORTB outputs...

[richard]

not to mention the port pins are still analog ,difficult to see in all the noise

missed ALLDIGITAL in there , my case rests

[astanapane]

Hi Henrik and Richard.

Many thanks for your prompt reply.

Really i'm not comfortable with programming, and i try to do what i really understand.

I think i solve the issue by changing the following lines to these.....

chkey:
if  portb.0 = 1 and portb.1 = 0 and portb.2 = 0 and portb.3 = 0 and portb.4 = 0 then return
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 0 and portb.3 = 0 and portb.4 = 0 then return
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 0 and portb.4 = 0 then return
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 1 and portb.4 = 0 then return  
if  portb.0 = 1 and portb.1 = 1 and portb.2 = 1 and portb.3 = 1 and portb.4 = 1 then pwok

I wish i could manage to learn how to store values and read them after. I know that the code is not efficient at all.

for now it works. I also change all the PORTX to LATX.

In the mean time i will try to learn and understand how to right values, then store them, read them and compare.

Many thanks once again.

[richard]

if you have a simple strategy to solve a task the program comes easily i find

my strategy for this would be :-
monitor the serial input for 0x07 chr [the start of a transmission pkt]
when you get an 07 read in the pkt
(a pkt when received can be decoded [eg '070D0000313B' the 5th byte is the key value data the sixth is a simple xor checksum])
check if the 5th byte is bel [(0x08) the go button]
if it is not
place it in a password length sized ring buffer and continue monitoring the serial input
if it is
check if ring buffer contains the password key code sequence
if it does
then its a winner
else
object to the failed attempt
keep reading in data

[richard]

i just can't help myself covid19 mania has set in

my take

'*  Notes   : This is a codelock based on the following components    *
'*          : PIC18F26K22 @ 64Mhz                                     *
'*          : 4D Systems ULCD 32DT diablo                             *
'*              note chksum untested                                  *
'**********************************************************************     
#CONFIG
  CONFIG  FOSC=INTIO67, PLLCFG=OFF, PRICLKEN=OFF, FCMEN=OFF, IESO=OFF
  CONFIG  PWRTEN=OFF, BOREN=SBORDIS, BORV=190, WDTEN=ON, WDTPS=32768
  CONFIG  CCP2MX=PORTC1, PBADEN=OFF, CCP3MX=PORTB5, HFOFST=ON, T3CMX=PORTC0
  CONFIG  P2BMX=PORTB5, MCLRE=EXTMCLR, STVREN=ON, LVP=OFF, XINST=OFF, DEBUG=OFF
  CONFIG  CP0=OFF, CP1=OFF, CP2=OFF, CP3=OFF, CPB=OFF, CPD=OFF, WRT0=OFF
  CONFIG  WRT1=OFF, WRT2=OFF, WRT3=OFF, WRTC=OFF, WRTB=OFF, WRTD=OFF, EBTR0=OFF
  CONFIG  EBTR1=OFF, EBTR2=OFF, EBTR3=OFF, EBTRB=OFF
#ENDCONFIG

define  OSC 64 
OSCCON    = $70   ; 64Mhz
OSCTUNE.6 = 1     ; Enable 4x PLL

while ! osccon2.7 :WEND ; to make sure the pll has stabilised before you run any other code 
  
TRISB = %10111111   
TRISC = %10111111 
ansela=0
anselb=0
anselc=0 

DEFINE HSER_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER_CLROERR 1 ' Clear overflow automatically
DEFINE HSER_SPBRG 138 ' 115200 Baud @ 64MHz, -0.08%
SPBRGH = 0
BAUDCON.3 = 1         ' Enable 16 bit baudrate generator

DEFINE HSER2_RCSTA 90h ' Enable serial port & continuous receive
DEFINE HSER2_TXSTA 24h ' Enable transmit, BRGH = 1
DEFINE HSER2_CLROERR 1 ' Clear overflow automatically
DEFINE HSER2_SPBRG 160 ' 38400 Baud @ 64MHz, -0.08%
SPBRGH2 = 1
BAUDCON2.3 = 1         ' Enable 16 bit baudrate generator 

DATAIN          var byte[5] ;key pkt
pword           var byte[4] ;holds password
pbuff           var byte[4] ;ringbuffer  must be pow of 2
buff            var byte[4] ;buffer to test password input
pbuffinx        var byte    ;ringbuffer index
chksum          var byte    ;the key pkt checksum if used
key             var byte    ;the key just read in
i               var byte


;num1    data  "070D0000313B" ; this is number 1
;num2      data  "070D00003238" ; this is number 2
;num3    data  "070D00003339" ; this is number 3
;num4    data  "070D0000343E" ; this is number 4
;num5    data  "070D0000353F" ; this is number 5
;num6    Data  "070D0000363C" ; this is number 6
;num7    Data  "070D0000373D" ; this is number 7
;num8    Data  "070D00003832" ; this is number 8
;num9    data  "070D00003933" ; this is number 9
;num10   data  "070D00002A20" ; this is number *
;num11   data  "070D0000303A" ; this is number 0
;num12   data  "070D00000802" ; this is go
pause 1000
HSERout2 ["ready"]   ;debug
arraywrite pword ,["*478"]  ;set password  
pbuffinx = 0

Start:
gosub readkey 
    if key != 8 then              ;not go key
        HSERout2 [key]            ;debug
        pbuff[pbuffinx] = key     ;add key to ringbuffer
        pbuffinx = (pbuffinx+1)&3 ;inc ringbuffer index
    else                          ;is go key
        for i = 0 to 3            ;read ringbuffer into buffer
            buff[i] = pbuff[(pbuffinx+i)&3]
        next
        HSERout2 [13,10,str buff\4,13,10];debug
        ARRAYREAD buff,4,fail,[WAITSTR pword\4]  ;test password
        goto unlocked
    endif
    goto start
unlocked:
    HSERout2 ["unlocked"] ;debug
    pbuffinx = 0  ;may not be needed
    goto start
fail:
    pbuffinx = 0  ;may not be needed
    HSERout2 ["failed"]  ;debug
goto start

readkey:         ;read key pkt
    HSERIN [WAIT($07), str datain\5] 
'    chksum=7               ;chksum untested proteus vterminal won't allow null chr to be sent
'    for i=0 to 4
'        chksum  =  chksum ^ datain[i] 
'    next
'    if    chksum  then  goto readkey  ;dud read
    key = datain[3]
return

[astanapane]

Hi Richard,

thanks so much for your help and time. I need to read carefully your code and understand it.

right now i'm testing the circuit.

The unused pins either i will pull them up with a resistors, or i will make ports outputs and set them to low.

I see in your code you have made those unused pins as inputs.

[richard]

The unused pins either i will pull them up with a resistors, or i will make ports outputs and set them to low.


I see in your code you have made those unused pins as inputs.

my answer is the same as you asked last time-


if your program if affected by unused pins then your program is defective.


when bread boarding unused pins left as inputs are less likely to be damaged by
inadvertent connection.


chip current consumption can be reduced by not having floating pins (by a few micro amps).
enabling weak pull on unused inputs will stop them floating but consumes a few micro watts.
setting unused pins low and as output consumes the minimal possible micro watts.
the same can be achieved leaving them as input but physically grounding them.

if the project is to be battery driven i will worry about unused pins in the final production version
otherwise it is of no consequence.

[astanapane]

Richard, thanks once again.

The final version will be under a 12V power supply. So there is no problem thinking about power consumption.

Physically the final version might have resistors to unused pins pulled to +5V.

At the moment i'm testing the circuit on breadboard for 3 days and there is no problem at all.

P.S.

/Henrik.

EDIT: One more thing: You're clearly reading PORTB which must mean you're using those five low bits as inputs, yet, at the top of the program you have TRISB = %00000000 which makes all of PORTB outputs...

So if you use for example the "if"

if LATB.0 = 0

that mean that we make the port as input? If that so, then what is the way to read the status of the port...."high" or "low" or even the value of the port?

In the mean time im reading the manual.

[richard]

So if you use for example the "if"

if LATB.0 = 0
that mean that we make the port as input? If that so, then what is the way to read the status of the port...."high" or "low" or even the value of the port?

combined with this continually showing up in your code


TRISA = %00000000 'use TRISA to specify which pin is (1 = input) and which (0 = output) (ALL pins are output)
TRISB = %00000000 'use TRISB to specify which pin is (1 = input) and which (0 = output) (RB7 PORTB.7 is the RX input pin of the EUART, the rest are output)
TRISC = %10000000 'use TRISC to specify which pin is (1 = input) and which (0 = output) (RC7 PORTC.7 is the RX input pin of the EUART, the rest are output)
'in PORTC the RC3 attached is an LED.

'------------------------------------------------------------------------|
'--------------------------- TRIS A B C ---------------------------------|
'------------------------------------------------------------------------|
' PORTA.7  PORTA.6  PORTA.5  PORTA.4  PORTA.3  PORTA.2  PORTA.1  PORTA.0 |
'  bit7     bit6     bit5     bit4     bit3     bit2     bit1     bit0   |
'   0        0        0        0        0        0        0        0     |
'------------------------------------------------------------------------|
'------------------------------------------------------------------------|
' PORTB.7  PORTB.6  PORTB.5  PORTB.4  PORTB.3  PORTB.2  PORTB.1  PORTB.0 |
'  bit7     bit6     bit5     bit4     bit3     bit2     bit1     bit0   |
'   0        0        0        0        0        0        0        0     |
'------------------------------------------------------------------------|
'------------------------------------------------------------------------|
' PORTC.7  PORTC.6  PORTC.5  PORTC.4  PORTC.3  PORTC.2  PORTC.1  PORTC.0 |
'  bit7     bit6     bit5     bit4     bit3     bit2     bit1     bit0   |
'   1        0        0        0        0        0        0        0     |

leads me to think there is fundamental lack of understanding here of pic i/o architecture
and the relation ship between ansel,port,lat and tris registers and their effect on
pin operations.

i would recommend a few led flashing exercises to become comfortable with i/o concepts

[astanapane]

Hi Richard,

i will try some LED blinks for sure.

many thanks.

[richard]

contrary to popular belief its a tricky subject

lesson 1 what happens here with and without the nop compiled in ? and why ?

;rmw test ,a led with a  270 ohm resistor in series to gnd placed each on pin a0 and a1
#CONFIG
  CONFIG  FOSC = INTIO67
  CONFIG  PLLCFG = OFF
  CONFIG  PRICLKEN = ON
  CONFIG  FCMEN = OFF
  CONFIG  IESO = OFF
  CONFIG  PWRTEN = ON
  CONFIG  BOREN = SBORDIS
  CONFIG  BORV = 190
  CONFIG  WDTEN = ON
  CONFIG  WDTPS = 32768
  CONFIG  CCP2MX = PORTC1
  CONFIG  PBADEN = OFF
  CONFIG  CCP3MX = PORTB5                                
  CONFIG  T3CMX = PORTC0
  CONFIG  HFOFST = ON
  CONFIG  P2BMX = PORTB5
  CONFIG  MCLRE = EXTMCLR
  CONFIG  STVREN = ON
  CONFIG  LVP = OFF
  CONFIG  XINST = OFF
  CONFIG  DEBUG = OFF
  CONFIG  CP0 = OFF
  CONFIG  CP1 = OFF
  CONFIG  CP2 = OFF
  CONFIG  CP3 = OFF
  CONFIG  CPB = OFF
  CONFIG  CPD = OFF
  CONFIG  WRT0 = OFF
  CONFIG  WRT1 = OFF
  CONFIG  WRT2 = OFF
  CONFIG  WRT3 = OFF
  CONFIG  WRTC = OFF
  CONFIG  WRTB = OFF
  CONFIG  WRTD = OFF
  CONFIG  EBTR0 = OFF
  CONFIG  EBTR1 = OFF
  CONFIG  EBTR2 = OFF
  CONFIG  EBTR3 = OFF
  CONFIG  EBTRB = OFF
#ENDCONFIG
'    DEFINE DEBUG_REG PORTB
'    DEFINE DEBUG_BIT 7      ;  if not used for pwr  
'    DEFINE DEBUG_BAUD 9600
'    DEFINE DEBUG_MODE 0  
'  ASM




    ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
led1 var lata.0
led2 var lata.1


loopy:
lata=0
led2 = !porta.1
;@ nop
led1 = porta.1


pause 3000
 
goto loopy

[richard]

lesson 2

what happens here and why ? does changing the lata initial value make a difference?

#CONFIG  CONFIG  FOSC = INTIO67
  CONFIG  PLLCFG = OFF
  CONFIG  PRICLKEN = ON
  CONFIG  FCMEN = OFF
  CONFIG  IESO = OFF
  CONFIG  PWRTEN = ON
  CONFIG  BOREN = SBORDIS
  CONFIG  BORV = 190
  CONFIG  WDTEN = ON
  CONFIG  WDTPS = 32768
  CONFIG  CCP2MX = PORTC1
  CONFIG  PBADEN = OFF
  CONFIG  CCP3MX = PORTB5                                
  CONFIG  T3CMX = PORTC0
  CONFIG  HFOFST = ON
  CONFIG  P2BMX = PORTB5
  CONFIG  MCLRE = EXTMCLR
  CONFIG  STVREN = ON
  CONFIG  LVP = OFF
  CONFIG  XINST = OFF
  CONFIG  DEBUG = OFF
  CONFIG  CP0 = OFF
  CONFIG  CP1 = OFF
  CONFIG  CP2 = OFF
  CONFIG  CP3 = OFF
  CONFIG  CPB = OFF
  CONFIG  CPD = OFF
  CONFIG  WRT0 = OFF
  CONFIG  WRT1 = OFF
  CONFIG  WRT2 = OFF
  CONFIG  WRT3 = OFF
  CONFIG  WRTC = OFF
  CONFIG  WRTB = OFF
  CONFIG  WRTD = OFF
  CONFIG  EBTR0 = OFF
  CONFIG  EBTR1 = OFF
  CONFIG  EBTR2 = OFF
  CONFIG  EBTR3 = OFF
  CONFIG  EBTRB = OFF
#ENDCONFIG
'    DEFINE DEBUG_REG PORTB
'    DEFINE DEBUG_BIT 7      ;  if not used for pwr  
'    DEFINE DEBUG_BAUD 9600
'    DEFINE DEBUG_MODE 0  
'  ASM




    ;ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
led1 var lata.0
led2 var lata.1


loopy:
lata=3   ;init porta
led2 = !porta.1


led1 = porta.1


pause 3000
 
goto loopy

[richard]

lesson 3 {i will leave off the config section its unchanged}

try this with latc initiaised with 1 2 or 3 and pins c0 and c1 grounded
the leds always reflect the initial state of latc , and in no way reflect the logical state of portc pins why?

    ANSELC = 0
    ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
    
led1 var lata.0
led2 var lata.1


loopy:
latc=0   ;init latc try 1 2 3
led2 = latc.1
led1 = latc.0


pause 3000
 
goto loopy

ps don't make grounded pin outputs

[astanapane]

lesson 2

what happens here and why ? does changing the lata initial value make a difference?

#CONFIG  CONFIG  FOSC = INTIO67
  CONFIG  PLLCFG = OFF
  CONFIG  PRICLKEN = ON
  CONFIG  FCMEN = OFF
  CONFIG  IESO = OFF
  CONFIG  PWRTEN = ON
  CONFIG  BOREN = SBORDIS
  CONFIG  BORV = 190
  CONFIG  WDTEN = ON
  CONFIG  WDTPS = 32768
  CONFIG  CCP2MX = PORTC1
  CONFIG  PBADEN = OFF
  CONFIG  CCP3MX = PORTB5                                
  CONFIG  T3CMX = PORTC0
  CONFIG  HFOFST = ON
  CONFIG  P2BMX = PORTB5
  CONFIG  MCLRE = EXTMCLR
  CONFIG  STVREN = ON
  CONFIG  LVP = OFF
  CONFIG  XINST = OFF
  CONFIG  DEBUG = OFF
  CONFIG  CP0 = OFF
  CONFIG  CP1 = OFF
  CONFIG  CP2 = OFF
  CONFIG  CP3 = OFF
  CONFIG  CPB = OFF
  CONFIG  CPD = OFF
  CONFIG  WRT0 = OFF
  CONFIG  WRT1 = OFF
  CONFIG  WRT2 = OFF
  CONFIG  WRT3 = OFF
  CONFIG  WRTC = OFF
  CONFIG  WRTB = OFF
  CONFIG  WRTD = OFF
  CONFIG  EBTR0 = OFF
  CONFIG  EBTR1 = OFF
  CONFIG  EBTR2 = OFF
  CONFIG  EBTR3 = OFF
  CONFIG  EBTRB = OFF
#ENDCONFIG
'    DEFINE DEBUG_REG PORTB
'    DEFINE DEBUG_BIT 7      ;  if not used for pwr  
'    DEFINE DEBUG_BAUD 9600
'    DEFINE DEBUG_MODE 0  
'  ASM




    ;ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
led1 var lata.0
led2 var lata.1


loopy:
lata=3   ;init porta
led2 = !porta.1


led1 = porta.1


pause 3000
 
goto loopy

excuse me starting from lesson 2.



First of all as from the configuration, all PORTA is digital with bit 7-2 as input and bit 1-0 to output.

now you have given a number to lata = 3. Even if you change this number nothing happen so far.

LED 2 is opossite state from porta.1

and LED 1 the same state as porta.1

We havent configured any port to high or low. By default the ports are set to low?

Could you also explain what is the logic behind the LATA.

[astanapane]

lesson 3 {i will leave off the config section its unchanged}

try this with latc initiaised with 1 2 or 3 and pins c0 and c1 grounded
the leds always reflect the initial state of latc , and in no way reflect the logical state of portc pins why?

    ANSELC = 0
    ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
    
led1 var lata.0
led2 var lata.1


loopy:
latc=0   ;init latc try 1 2 3
led2 = latc.1
led1 = latc.0


pause 3000
 
goto loopy

ps don't make grounded pin outputs

ok i got this....as i did the changing of the numbers from 0 to 3. It was obvious that those numbers represents binary numbers of the portc and corresponds to LED1 and LED2(assigned via software)

I did add one more latc.2 to ground and placed one more LED to porta.2 (changed the trisa as well), then went up to 7th number and realised the change in binary on the porta.

I would love if you could explain to me were this could be useful in real life. I know time is limitted but some time i would love to read your explanation.

Many thanks.

[richard]

excuse me starting from lesson 2.
First of all as from the configuration, all PORTA is digital with bit 7-2 as input and bit 1-0 to output.

all PORTA is not digital its all analogue

now you have given a number to lata = 3. Even if you change this number nothing happen so far.

the result is fixed , changing the input conditions will never change the result . why ?

LED 2 is opposite state from porta.1

no its not its always set. why ?

and LED 1 the same state as porta.1

no its not its never set. why ?

[richard]

lesson 3
ok i got this....as i did the changing of the numbers from 0 to 3. It was obvious that those numbers represents binary numbers of the portc and corresponds to LED1 and LED2(assigned via software)

completely missing the point that:-
portc pins 0 and 1 are shorted to ground and will always be at logic zero level.
latc always reads back as the last value written to it [even when port is set as input ]
latc does not represent the logic level as applied to the pins

I would love if you could explain to me were this could be useful in real life.

if you don't know how it works how can you use it ?

[astanapane]

all PORTA is not digital its all analogue





the result is fixed , changing the input conditions will never change the result . why ?


no its not its always set. why ?

no its not its never set. why ?

My bad, didint notice

;ANSELA = 0

Now things are more confused.

the result is fixed , changing the input conditions will never change the result . why ?

Really dont know. It might have to do with the analogue settings on the porta. I made all port digital and response to value changed. But really cant understand the reason.

no its not its always set. why ?

no its not its never set. why ?

ports configured as analogue by default are read as low?

[richard]

ports configured as analogue by default are read as low?

nearly , pins configured as analogue always read as low

[astanapane]

nearly , pins configured as analogue always read as low

these are my notes. I think i will try to understand why these happens.

What i cannot understand is the writting to the portx or to latx.

For example if we give alias:

LED1 var LATX

are we correspond the name to the LATX (not really writting to the LATX)

So the same applies for the PORTX

LED1 var PORTX

The problem comes as i understand when we really write to the LATx or PORTx. Values are different.

I need to do some exercises more on this.

[astanapane]

On the diagram above the Flip flop....is it an edge triggered D flip flop?

If so i will focus on the schematic and i will try to understand what is going on in there.

[richard]

when you write to lata you write directly to the porta output latches, only the pins declared as outputs are connected to the pins via the trisa "switch".
when you write to porta you write directly to the porta output latches, only the pins declared as outputs are connected to the pins via the trisa "switch".
when you read porta you read the digital logic level of all the porta pins , analog pins always read low
when you read lata you read the porta output latches value not the digital logic level of all the porta pins
when you write to a lata.pin you read the porta output latch value into the alu then,
logically AND it with that pins bit value as 0 to CLEAR the pin
or
logically OR it with that pins bit value as 1 to SET the pin
then write the result back to the porta output latches

when you write to a porta.pin you read the porta pins value into the alu then,
logically AND it with that pins bit value as 0 to CLEAR the pin
or
logically OR it with that pins bit value as 1 to SET the pin
then write the result back to the porta output latches

if you did lesson one you would have noticed that port pins are subject to real world load conditions and that reading the pin value is not always what you wrote to it
you need to allow for pin loading

lesson two shows you can set and clear an analog pin made output but you can never read an analog pin properly

lesson three shows you can read and write to output latches but they may not represent the pin values of that port they are always what you last wrote to the latch



the diagram is for 1 pin

[richard]

On the diagram above the Flip flop....is it an edge triggered D flip flop?

makes no difference

[astanapane]

im trying to understand what is going on with the help of the schematic , in lesson 1.

Please give me some time.

I just need to clarify something.

when you write to all LATA register "0", is that just a number or is a bit? For example if we write

LATA = 5

Is that a number or is translated to a binary 00000101.

So this writting to lat register

LATA = 5 

represents the 

LATA = %00000101

[richard]

5 dec = 5 hex = bin 101 , numbers are just numbers
all digital computers to date are binary devices and that's all they can cope with
programs like pbp C mpasm ...... allow humans to specify numbers in any form we are comfortable with

generally we have conventions to remove number base confusion
eg 5 = $5 = 0x05 =%00000101 = 0b00000101= %101 =$05 = %000000000000000101 . the chip only ever sees the binary version

[astanapane]

What i mean is if that numbers corresponds to 8 LATx for example for portA

For example if we write

LATA = 5

is that number correspond to binary 8 bit LATA.x , so that number 5 will write only to %00000101 which is the LATA.0 and LATA.2

Can we write a number then to only one LATA.x

for example can we write

LATA.0 = 5

What that number will represent for the LATA.0

based on the schematic logic gates receive only 0s or 1s. So LATA.x could only get 0s or 1s. Is that right?

[richard]

LATA = 5
replaces the entire contents of lata latch with 5

LATA.0 = 5

is a syntax error a bit can only be 0 or 1

lata.0 is bit 0 of the lata latch

[richard]

lesson 4 bit manipulation need 8 leds attached to porta:0-7

These four routines [below] march a single lit led across the eight pins of porta from a0 to a7 when inserted in the shell provided.
try each, which is the best do you think
one of them could have "issues" @ 64mhz. which one? and why?


can you reverse the direction of the march for each one ?
can you light up the leds and march a single unlit led across the eight pins of porta from a0 to a7 ?

i.
PORTA.0=1
WHILE PORTA
PAUSE 200
PORTA=PORTA<<1
WEND
ii.
PORTA.0=1
WHILE PORTA
PAUSE 200
PORTA=PORTA*2
WEND


iii.
PORTA.0=1
PAUSE 200
PORTA.0=0
PORTA.1=1
PAUSE 200
PORTA.1=0
PORTA.2=1
PAUSE 200
PORTA.2=0
PORTA.3=1
PAUSE 200
PORTA.3=0
PORTA.4=1
PAUSE 200
PORTA.4=0
PORTA.5=1
PAUSE 200
PORTA.5=0
PORTA.6=1
PAUSE 200
PORTA.6=0
PORTA.7=1
PAUSE 200
PORTA.7=0

iv.
PORTA=1
PAUSE 200
PORTA=2
PAUSE 200
PORTA=4
PAUSE 200
PORTA=8
PAUSE 200
PORTA=16
PAUSE 200
PORTA=32
PAUSE 200
PORTA=64
PAUSE 200
PORTA=128
PAUSE 200
PORTA=0

#CONFIG  CONFIG  FOSC=INTIO67, PLLCFG=OFF, PRICLKEN=OFF, FCMEN=OFF, IESO=OFF
  CONFIG  PWRTEN=OFF, BOREN=SBORDIS, BORV=190, WDTEN=ON, WDTPS=32768
  CONFIG  CCP2MX=PORTC1, PBADEN=OFF, CCP3MX=PORTB5, HFOFST=ON, T3CMX=PORTC0
  CONFIG  P2BMX=PORTB5, MCLRE=EXTMCLR, STVREN=ON, LVP=OFF, XINST=OFF, DEBUG=OFF
  CONFIG  CP0=OFF, CP1=OFF, CP2=OFF, CP3=OFF, CPB=OFF, CPD=OFF, WRT0=OFF
  CONFIG  WRT1=OFF, WRT2=OFF, WRT3=OFF, WRTC=OFF, WRTB=OFF, WRTD=OFF, EBTR0=OFF
  CONFIG  EBTR1=OFF, EBTR2=OFF, EBTR3=OFF, EBTRB=OFF
#ENDCONFIG


define  OSC 64 
OSCCON    = $70   ; 64Mhz
OSCTUNE.6 =   1     ; Enable 4x PLL




TRISA  = NOT 17 
ansela = ~ $FF




LOOPY:
    
  ;insert code here


    PAUSE 3000
GOTO LOOPY

[astanapane]

im still in lesson 1.



i need to completely understand it with the use of the port schmeatic.

[richard]

make lesson 1 loop like this and try with and without the nop

loopy:
lata=2
pause 10
porta.1 = 0
;@ nop
porta.0 = 1




pause 1000
 
goto loopy

the secret is that leds when forward biased charge up , when you set them low the charge can hold the pin high long enough
to trigger a rmw event on a fast chip. the nop allows enough time for the charge to dissipate {62 nano seconds}

[astanapane]

one by one,

i'm doing some test. Really i have my own way to catch up and understand things.

first of all for lata we can only write up to 255 as it is 8 bit.

I'm still figuring out step by step the diagram.

[astanapane]

this is really helpful for me as well.

https://download.mikroe.com/document...c/help/rmw.htm

[astanapane]

ok i think i have some how understood the concept.

my question is.

How could we assign a value that can be stored in memory and represent the state of the pin itself. (0 or 1)

but at the same time to not read the actual pin, but the value that is stored in memory.

[richard]

How could we assign a value that can be stored in memory and represent the state of the pin itself. (0 or 1)


but at the same time to not read the actual pin, but the value that is stored in memory.

simple, to read the value assigned to pins designated as output read latx its value is always what you last set it to
the latx value of pins set as input is meaningless in regards to actual pin logic level

to read the actual pin logic levels at a point in time read portx , its always the actual pin value at read time

pin and latx values are not necessarily equal at a point in time, pins set as output are subject to real world physical constraints dictated by the load impedance they are driving

[astanapane]

i did a small test but it is not what i need.

I would like now once again to clear the following.

Henrik said

"One more thing: You're clearly reading PORTB which must mean you're using those five low bits as inputs, yet, at the top of the program you have TRISB = %00000000 which makes all of PORTB outputs..."

As this statement, how could we read the status of the actual pin without using the port as input. Could you please explain to me the method?

ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
                             
led1 var porta.0    ; alias led1 to porta.0
led2 var porta.1    ; alias led2 to porta.1
x    var bit            ; tried to use X var as a bit in order to hold the value of the actual status of the pin.

lata = 0               ; based on the schematic, we write to LATA and clear the ports 

x = 0                  ; we write 0 to var X


loopy:
lata.0 = 1           ; we write 1 to lata.0
gosub holdmem  ; gosub to holdmem

pause 500
read 5,led2        ; write the value of the location 5 to led2

pause 500
lata.0 = x          ; write the value of X to lata.0
lata.1 = x          ; write the value of X to lala.1

pause 1000
goto loopy

holdmem:
write 5,led1  ; read the state of the porta.0 and place it to location 5 in memory.
return

[richard]

As this statement, how could we read the status of the actual pin without using the port as input. Could you please explain to me the method?

simply put you cannot , reading portx is the only direct way to read the actual status of the pins.

what henrik means is why would you read a port to read the value of outputs you have already set. the outputs will be at the level you set them to
(after a suitable interval to allow pin to settle) {providing load is acceptable}.

what are trying to do ?

[richard]

do you mean something like this

no need to wear out the eeprom

ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
                             
led1 var porta.0    ; alias led1 to porta.0
led2 var porta.1    ; alias led2 to porta.1
x    var bit            ; tried to use X var as a bit in order to hold the value of the actual status of the pin.


 


x = 0                  ; we write 0 to var X




loopy:
lata.0 = 1           ; we write 1 to lata.0
gosub holdmem  ; gosub to holdmem


pause 500
led2  = x      ; write the value of x to led2
pause 500
led1=0
@ nop
led2=0
pause 1000
goto loopy


holdmem:
x = led1  ; read the state of the porta.0 and place it in x
'x = lata.0  ;or  read the state of the lata.0 and place it in x
return
 
goto loopy

[astanapane]

simply put you cannot , reading portx is the only direct way to read the actual status of the pins.

what henrik means is why would you read a port to read the value of outputs you have already set. the outputs will be at the level you set them to
(after a suitable interval to allow pin to settle) {providing load is acceptable}.

what are trying to do ?

The program for the lockcode, at the moment works fine. As mentioned in my first post im not a programmer, i had to find a way to make it work.

So the best suitable solution for me is to light up some LEDs and then read the status of the ports for confirmation.

That's why i made those pins as output and then read the status to confirm if they are 0 or 1.

[astanapane]

do you mean something like this

no need to wear out the eeprom

ANSELA = 0
    DEFINE OSC 64 
    OSCCON = $70
    OSCTUNE.6 = 1
    TRISA = %11111100 
                             
led1 var porta.0    ; alias led1 to porta.0
led2 var porta.1    ; alias led2 to porta.1
x    var bit            ; tried to use X var as a bit in order to hold the value of the actual status of the pin.


 


x = 0                  ; we write 0 to var X




loopy:
lata.0 = 1           ; we write 1 to lata.0
gosub holdmem  ; gosub to holdmem


pause 500
led2  = x      ; write the value of x to led2
pause 500
led1=0
@ nop
led2=0
pause 1000
goto loopy


holdmem:
x = led1  ; read the state of the porta.0 and place it in x
'x = lata.0  ;or  read the state of the lata.0 and place it in x
return
 
goto loopy

yes i think this is what i wanted to do. But when we use the following command:

x = led1  ; read the state of the porta.0 and place it in x

arent we write to EEPROM? Or this is temprorarly held in memory?