A way to define specific ports for output bits? start output in middle port?

[wdmagic]

say I wanted to output binary numbers (4bit, or 3 bit, or 5 bit) my choice- but lets say 3bit right now so I want to output a number (0-7). the trick is I dont want to start with PORTx.0 to PORTx.2, say i want to use PORTx 3 - 5. is this possible and how would I do it. ???

also if this is possible can you use any ports to build an output, say you need 8 ports to build a byte output could you build 8 seperate I/O's from different ports like

MYBYTE VAR BYTE

MYBYTE.0 = PORTA.7
MYBYTE.1 = PORTA.3
MYBYTE.2 = PORTB.4
MYBYTE.3 = PORTB.5
MYBYTE.4 = PORTB.6
MYBYTE.5 = PORTC.2
etc....

the first question is primary, the second is elective, just curious

[wdmagic]

Ok right now Im having a problem, On PORTB.0 = INT0
now I want to use PORTB.1-3 as a binary output from 0-7
but since my portb.0 isnt available, how do i set it to start my output at bit 2 (portb.1)
my only available pins right now is portb 1-5, I need a 3bit binary output that will go to a 3bit to 8decimal chip that drives 8 leds.
I was hoping theres a command like in the LCD commands to say start bit = ?

[HenrikOlsson]

Hi,
A bit convoluted but it hopefully shows what's happening:

Temp = PortB.0 & %11110001        ' Read PortB into Temp and clear bits 1-3 ( & is bitwise AND)
Value = 5                                      ' This is the value that will be written to bits 1-3
Value = Value << 1                          ' Shift value to the left one place to "align it" with bits 1-3 
PortB = Temp | Value                     ' Write new value back to PortB. ( | is bitwise OR )

Or

Temp = PortB.0
Value = 5
Temp.1 = Value.0
Temp.2 = Value.1
Temp.3 = Value.2
PortB.0 = Temp

Or, if a bit bitflipping on the port doesn't matter

Value = 5
PortB.1 = Value.0
PortB.2 = Value.1
PortB.3 = Value 2

And I'm sure there are other ways.

/Henrik.

[Acetronics2]

Hi,

I think Darrel wrote something about that ... some times ago.

this was the origin of "LCD on Any pin" !

Here it is ...

'****************************************************************
'*  Name    : VirtualPort.bas                                   *
'*  Author  : Darrel Taylor                                     *
'*  Date    : 3/20/2006                                         *
'*  Version : 1.1                                               *
'*  Notes   : Allows you to control non-contiguous PINs/BITs    *
'*          : as if they were a contiguous PORT/Register        *
'****************************************************************
'*  See this Webpage for more info                              *
'*  http://www.picbasic.co.uk/forum/showthread.php?t=4074       *
'****************************************************************
'*  with assistance from:                                       *
'*   1.1    SteveB                                              *
'*   1.2    ?                                                   *
'****************************************************************

disable debug


VP_DelayCount  VAR WORD BANK0  ; Used for internal Delay only

ASM
PortVar set 0
   ; nolist

;----[Defines a Virtual PIN in a Virtual PORT]--------------------------------
Vpin  macro  Vb, P, Pbit
  local Vaddr, VarBit
    if (Vb < 16)                                 ; If Var bit# is < 16 
      if (Pbit < 8)                              ; and Port bit# is < 8
          if (PortAction < 2)                      
              if (Vb > 7)                        ; Var Bit > 7, use high word
Vaddr  = PortVar + 1
VarBit = Vb - 8
              else
Vaddr  = PortVar
VarBit = Vb
              endif
          endif
          if (PortAction == 0)                   ; read
              MOVE?TT  P, Pbit, Vaddr, VarBit      
          else
              if (PortAction == 1)               ; write
                  MOVE?TT  Vaddr, VarBit, P, Pbit  
              else
                  if (PortAction == 2)           ; output
                      PhysicalPort  P            ; only if it's a Real PORT
                      if (Found == 1)
                          OUTPUT?T  P, Pbit
                      endif
                  else
                      if (PortAction == 3)       ; input
                          PhysicalPort  P        ; only if it's a Real PORT
                          if (Found == 1)
                              INPUT?T  P, Pbit
                          endif       
                      endif
                  endif
              endif
          endif
      else
            error Vpin - PORT BIT [Pbit] Out of Range
      endif  
    else
        error Vpin - Variable BIT [Vb] Out of Range
    endif  
  endm

;----[Copy a bit to a Pin]----------------------------------------------------
Vbit  macro  Rin,Bin, Rout,Bout
    MOVE?TT  Rin,Bin, Rout,Bout
  endm
  
;----[Read a Virtual Port]----------------------------------------------------
ReadPort  macro PortVar, PinMacro
  ; nolist
PortAction = 0  ; Read
       PinMacro
    list  
  endm
    
;----[Write a variable to a Virtual Port]-------------------------------------
WritePort  macro PortVar, PinMacro
  ; nolist
PortAction = 1
        PinMacro
    list  
  endm
  
;----[Set ALL pins of a virtual Port to OUTPUT]-------------------------------
OutputPort  macro  PinMacro
  ; nolist
PortAction = 2
        PinMacro
    list  
  endm
    
;----[Set ALL pins of a virtual Port to INPUT]--------------------------------
InputPort  macro PinMacro
  ; nolist
PortAction = 3
        PinMacro
    list  
  endm

; These 4 are useful for Port Control Pins, such as Enable and Direction pins
; They don't change the TRIS state during INPUT/OUTPUT calls, which makes
; bi-directional ports a lot easier.
  
;----[Make a Pin LOW]---- Does not change TRIS bit ---------------------------
PinHigh  macro  P, B
  ; nolist
    if (PortAction < 2)   ; Don't do anything on Input or Output pass
        MOVE?CT  1, P, B  ; Make Pin HIGH
    endif
    list  
  endm

;----[Make a Pin LOW]---- Does not change TRIS bit ---------------------------
PinLow  macro  P, B
  ; nolist
    if (PortAction < 2)   ; Don't do anything on Input or Output pass
        MOVE?CT  0, P, B  ; Make Pin LOW
    endif
    list  
  endm

;----[Similar to PAUSEUS, but ASM interrupt compatible]---(accurate to 1uS)---
DelayUS  macro T
  ; nolist
  local InstCount, LoopCount, DelayLoop, LoopsDone, LeftOver, Offset
; -- Calculate number of 3 cycle loops plus leftover nop's to execute --
InstCount = ((OSC*10/4)*T+5)/10  ; Inst cycles required for delay (Rounded UP)
LoopCount = InstCount / 3
    if (LoopCount > 255)
Offset = (LoopCount >> 8) * 7 + 4
    else
Offset = 0
    endif
; -- Adjust for HighByte --
InstCount = InstCount - Offset
    if (Offset > (LoopCount & 0FFh))
InstCount = InstCount - 4
    endif
LoopCount = InstCount / 3
    if (LoopCount > 255)
Offset = (LoopCount >> 8) * 7
    else
Offset = 0
    endif
LeftOver  = InstCount % 3
;-------------------------------------------
    if (LoopCount > 0)
        MOVE?CW  LoopCount, _VP_DelayCount
DelayLoop
        decfsz   _VP_DelayCount, F               ;  1
        goto     DelayLoop                       ;  2    3 per loop, under 256
    
        if (LoopCount > 255)
            movf     _VP_DelayCount + 1, W       ;  1    
            btfsc    STATUS, Z                   ;  1    
            goto     LoopsDone                   ;  2    4 on last loop
            
            decf     _VP_DelayCount + 1, F       ;  1    
            goto     DelayLoop                   ;  2    7 per highbyte count 
LoopsDone
        endif
    endif
    if (LeftOver > 0)
        nop
    endif
    if (LeftOver > 1)
        nop
    endif

    list  
  endm
  
;----[Pulse a Pin LOW for a specified number of uS]---------------------------
PulseLow  macro P, B, Time
  ; nolist
    PhysicalPort  P            
    if (Found == 1)            ; only if it's a Real PORT
        if (PortAction < 2)
          MOVE?CT  0, P, B
          DelayUS  Time
          MOVE?CT  1, P, B
        endif
    else
        error "PulseLow - Can only Pulse a Physical Pin"
    endif
    list  
  endm

;----[Pulse a Pin HIGH for a specified number of uS]---------------------------
PulseHigh  macro P, B, Time
  ; nolist
    PhysicalPort  P            
    if (Found == 1)            ; only if it's a Real PORT
        if (PortAction < 2)
          MOVE?CT  1, P, B
          DelayUS  Time
          MOVE?CT  0, P, B
        endif
    else
        error "PulseHigh - Can only Pulse a Physical Pin"
    endif
    list  
  endm
  
;----[Is the PIN a Physical PIN or just a register?]-----(Compile Time Only)--
PhysicalPort macro P
  ; nolist
Found = 0
    ifdef GPIO
        if P == GPIO
Found = 1
        endif
    endif
    ifdef PORTA
        if P == PORTA
Found = 1
        endif
    endif
    ifdef PORTB
        if P == PORTB
Found = 1
        endif
    endif
    ifdef PORTC
        if P == PORTC
Found = 1
        endif
    endif
    ifdef PORTD
        if P == PORTD 
Found = 1
        endif
    endif
    ifdef PORTE
        if P == PORTE
Found = 1
        endif
    endif
    ifdef PORTF
        if P == PORTF
Found = 1
        endif
    endif
    ifdef PORTG
        if P == PORTG
Found = 1
        endif
    endif
    ifdef PORTH
        if P == PORTH
Found = 1
        endif
    endif
    ifdef PORTI
        if P == PORTI
Found = 1
        endif
    endif
    ifdef PORTJ
        if P == PORTJ
Found = 1
        endif
    endif
    ifdef PORTK
        if P == PORTK
Found = 1
        endif
    endif
  
    list
  endm
    
  list
ENDASM
                                                    
disable debug
;----[Trick PBP into including certain macro's]---Doesn't use any code space--
@  ifdef NotCompiled
@DummyPort = 0
 DummyPort VAR BYTE EXT
       OUTPUT DummyPort.0       ; OUTPUT?T
       INPUT  DummyPort.0       ; INPUT?T
@  endif

enable debug

Alain

[Ioannis]

OK, Alain. Very nice idea to set or reset a bit!



Ioannis

[wdmagic]

I kinda like your idea henrik, but im alittle confused on a couple of the terms "bitwise, shifting" I dont normally do this kind of thing in code.
My PORTB.0 is being used as a interupt, is there a way to do something to shift the number over
Sorry ACE i was totally confused by that code.

What I need with very little coding.
MYVAL = 7 ' 00000111
SHIFTCODE MYVAL < ? & make bit.0 1 ' New MYVAL = 00001111
PORTB = MYVAL

now as far as i understand I need to make sure any code that is sent to portb has portb.0 as a 1, since i need to keep it high, until a button is pressed. I dont want to trigger a INT by sending a low to that pin. but I need to shift the first 3 bits to the left and make sure the first bit ends up a 1.

[wdmagic]

heres a copy of an sample program code needs to be fixed, think of it lighting 3 led's in binary sequence

PORTB.0 = INT ' Just a INT Code Placeholder
X VAR Byte : X = 0

MyLOOP:
PORTB.1-3 = X ' Shifting Code Needed
pause 1000
X = X + 1
if X > 7 then X = 0
Goto MyLoop

[HenrikOlsson]

Hi,
First of all, there's an error in my previous example. The shift left operator is of course << and nothing else, sorry about that. The "edit window" is closed so I can't go back and fix it.

With your code as an example, try this:

MyLoop:
  Temp = PortB & %11110001
  PortB = Temp | (X << 1)
  X = X + 1
  IF X > 7 THEN X = 0
  PAUSE 1000
Goto MyLoop

Lets go thru the two first lines:
Temp = PortB & %11110001 - This reads the state of PortB into a variable called Temp and ANDS it with the value 14. What's happening there is that Temp will be whatever PortB is except for bits 1-3 which will be cleared to 0.
PortB = Temp | (X << 1) - This takes the value of Temp and ORs with the value of X shifted one "step" to the left. Remember that Temp is a copy of what PortB was except bits 1-3 which are now 0. So if X is 3 (%00000011) PortB will be %xxxx011x where x is whatever was there before because X is shifted one "step" before ORing it with Temp.

When doing a bitwise AND on two numbers each bit must be '1' in BOTH numbers for the bit to be '1' in the "result. So when doing a bitwise and with a value where certain bits are '0' those bits will be '0' in the result, example.
%11111111 & %00000000 = %00000000
%11111111 & %11110000 = %11110000
%11001000 & %00001111 = %00001000

When doung a biteise OR on two numbers it's enough that a bit in either number is '1' for that bit to be '1' in the result, example:
%11111111 | %00000000 = %11111111
%00000000 | %00001111 = %00001111
%11110000 | %00001111 = %11110000

So in the above code we read in PortB, clear bits 1-3 and put the value of X in those 3 bits.

/Henrik.

[Acetronics2]

just some MORE browsing job ...

http://www.picbasic.co.uk/forum/showthread.php?p=22065

yes ... relevant threads already exist

@#14 ... how to use Virtualport.bas

Next step ???

Alain

[wdmagic]

So if i dont care about PORTB's other bits could it work like this?

MyLoop:
Temp = X << 1
TEMP.0 = 1 ' to Keep PORTB.0 High
PortB = Temp
X = X + 1
IF X > 7 THEN X = 0
PAUSE 1000
Goto MyLoop

[HenrikOlsson]

Hi,
Yes, if you don't care what's happening with PortB.4-7 then that should work.

If PortB.4-7 are outputs then your aproach won't work properly since you'll overwrite those bits with the value of Temp. That's the reason for first reading PortB and ANDing it with %11110001 so that we ONLY change the state of bits 1-3 when ORing Temp with X. If all bits except 1-3 are inputs then your aproach should work - which brings me to the next point...

I suspect the purpose with "keeping PortB.0 high" is to prevent it from tripping an interrupt? If so I don't think you need to worry about that.
When PortB.0 is setup as an input, it doesn't matter what you write to PortB.0 - it'll never actually "get to" the actual pin since the output driver is disabled. Look at the block diagram of the pin in the datasheet, this is for the 16F887 it may differ slightly from whatever device you're using:



The "interrupt path" is drawn in blue here. The output driver is circled in red. As you can see the output driver is enabled/disabled by D-type flip-flop which is controlled by writing to TRISB. So, even if you write '0' to PortB.0 it'll never reach the pin and cause an interrupt since that '0' won't "go thru" the output driver.

/Henrik.

[wdmagic]

ok thanks henrik, yes there is nothing connected to portb 4-7, theres no room for me to add those ports to anything as the ports are blocked by other circuit traces. and yes I was thinking of the INT on portb.0 , but I do see your logic there, since ive made it a tris=1 then it shouldnt change state even if I tell it to in code., thanks for the diagram, if I didnt need the INT and if I could get to the other B pins i would just use the 8 leds direct but I dont have that option so this will work, thanks.