Single PIC to Blink 5 LEDs Independently?

[Darrel Taylor]

The question now becomes: is there a way to set the on/off periods individually for each of the 5 LEDs?

Yes, but you have to create the individual ON/OFF periods.
That code only has 1 period, for a 50% dutycycle.

So many things you can do.
So little time to explain.
Twinkle Twinkle little tree ...

DEFINE OSC 4
DEFINE BLINKYFREQ 100  ; 10mS periods

' ***************************************************************
' Device Fuses
' ***************************************************************
#CONFIG
   __config _CONFIG1, _FOSC_INTOSC & _WDTE_ON & _PWRTE_ON & _MCLRE_OFF & _CP_OFF & _CPD_OFF
   __config _CONFIG2, _PLLEN_OFF & _STVREN_ON & _BORV_LO & _LVP_OFF
#ENDCONFIG

OSCCON   = %01101000        ' 4MHz internal osc

;----------------------------------------------------------------
LEDcount    CON 5                  ; Number of LEDs on the PORT
OnTimes     DATA  50,22,38,75, 5   ; default periods for each Output
OffTimes    DATA 150,45,38,95,34

;----------------------------------------------------------------
#DEFINE USE_RANDOM_SEQUENCE     ; comment for contiuous Sequence
#IFDEF USE_RANDOM_SEQUENCE
    RND     VAR WORD : RND = 13864
    MIN_ON  CON 10                  ; Minimum random ON time
    MAX_ON  CON 100                 ; Maximum random ON time
    MIN_OFF CON 10                  ; Minimum random OFF time
    MAX_OFF CON 100                 ; Maximum random OFF time
    RandPeriod VAR WORD[LEDcount]
    RandPeriods DATA WORD 1000, WORD 1250, WORD 1500, WORD 1750, WORD 2000
#ENDIF

;----------------------------------------------------------------
CCPR1val   CON EXT      : @CCPR1val = (OSC*1000000/4)/ BLINKYFREQ
CCPR1      VAR WORD EXT : @CCPR1 = CCPR1L
Timer1     VAR WORD EXT : @Timer1 = TMR1L
CCPIF      VAR PIR1.2

LoopLED    VAR BYTE[LEDcount]
OnTime     VAR BYTE[LEDcount]
OffTime    VAR BYTE[LEDcount]
x          VAR BYTE

;----[Initialize]------------------------------------------------
FOR x = 0 to LEDcount - 1         ; load the periods from EEPROM
    READ OnTimes+x, OnTime(x)
    READ OffTimes+x, OffTime(x)
    #IFDEF USE_RANDOM_SEQUENCE
        READ RandPeriods+(x<<1), WORD RandPeriod(x)
    #ENDIF
NEXT X

;-- setup CCP1 and Start Timer1 --
CCPR1   = CCPR1val     ; set compare value
CCP1CON = %00001011    ; compare mode, special event 
Timer1  = 0            ; clear Timer1
T1CON.0 = 1            ; start Timer1

ANSELC = 0
TRISC = 0              ; PORTC all OUTPUT

;----[Main Program Loop]----------------------------------------
Main: 
    x = (x + 1) // LEDcount
    PORTC.0(x) = !!(LoopLED(x) < OnTime(x))
    LoopLED(x) = (LoopLED(x) + 1) // (OnTime(x) + OffTime(x))
    #IFDEF USE_RANDOM_SEQUENCE
        RandPeriod(x) = RandPeriod(x) - 1
        IF RandPeriod(x) = 0 THEN
            READ RandPeriods+(x<<1), WORD RandPeriod(x)
            RANDOM RND
            OnTime(x) = (MAX_ON - MIN_ON)* RND.HighByte / 255 + MIN_ON 
            OffTime(x)= (MAX_OFF - MIN_OFF)* RND.LowByte / 255 + MIN_OFF
        ENDIF
    #ENDIF
    IF x != (LEDcount - 1) THEN Main

Waiting: IF !CCPIF THEN Waiting
    CCPIF = 0
GOTO Main

[RossWaddell]

My god ... it's ... it's beautiful Just like a 1960's string of Christmas tree lights, the exact effect I'm after. I can't thank you enough, Darrel!

One last query (I hope) - since I only need 5 output pins I would like to convert this to a 12F683. When I do, I get the 'ol "Redefinition of VAR" error pointing to this line:

CCPR1      VAR WORD EXT : @CCPR1 = CCPR1L

The whole code is here:

'****************************************************************
'*  Name    : UNTITLED.BAS                                      *
'*  Author  : Ross Waddell                                      *
'*  Notice  : Copyright (c) 2012 [select VIEW...EDITOR OPTIONS] *
'*          : All Rights Reserved                               *
'*  Date    : 10/27/2012                                        *
'*  Version : 1.0                                               *
'*  Notes   : PIC12F683                                                 *
'*          :                                                   *
'****************************************************************

DEFINE OSC 4
DEFINE BLINKYFREQ 100  ; 10mS periods

' ***************************************************************
' Device Fuses
' ***************************************************************
' PIC chip data sheets can be found here: C:\Program Files\Microchip\MPASM Suite
#CONFIG
       __config _INTRC_OSC_NOCLKOUT & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _BOD_ON & _CP_OFF & _CPD_OFF
#ENDCONFIG

OSCCON   = %01100000        ' 4MHz internal osc

;----------------------------------------------------------------
LEDcount    CON 5                  ; Number of LEDs on the PORT
OnTimes     DATA  50,22,38,75,17   ; default periods for each Output
OffTimes    DATA 150,45,38,95,117

;----------------------------------------------------------------
#DEFINE USE_RANDOM_SEQUENCE     ; comment for contiuous Sequence
#IFDEF USE_RANDOM_SEQUENCE
    RND     VAR WORD : RND = 13864
    MIN_ON  CON 15                  ; Minimum random ON time
    MAX_ON  CON 115                 ; Maximum random ON time
    MIN_OFF CON 15                  ; Minimum random OFF time
    MAX_OFF CON 200                 ; Maximum random OFF time
    RandPeriod VAR WORD[LEDcount]
    RandPeriods DATA WORD 1000, WORD 1250, WORD 1500, WORD 1750, WORD 2000
#ENDIF

;----------------------------------------------------------------
CCPR1val   CON EXT      : @CCPR1val = (OSC*1000000/4)/ BLINKYFREQ
CCPR1      VAR WORD EXT : @CCPR1 = CCPR1L
Timer1     VAR WORD EXT : @Timer1 = TMR1L
CCPIF     VAR PIR1.5

LoopLED    VAR BYTE[LEDcount]
OnTime     VAR BYTE[LEDcount]
OffTime    VAR BYTE[LEDcount]
x          VAR BYTE

;----[Initialize]------------------------------------------------
FOR x = 0 to (LEDcount - 1)         ; load the periods from EEPROM
    READ OnTimes+x, OnTime(x)
    READ OffTimes+x, OffTime(x)
    #IFDEF USE_RANDOM_SEQUENCE
        READ RandPeriods+(x<<1), WORD RandPeriod(x)
    #ENDIF
NEXT X

;-- setup CCP1 and Start Timer1 --
CCPR1   = CCPR1val     ; set compare value
CCP1CON = %00001011    ; compare mode, special event 
Timer1  = 0            ; clear Timer1
T1CON.0 = 1            ; start Timer1

ANSEL  = 0
TRISIO = 0             ; PORTC all OUTPUT

;----[Main Program Loop]----------------------------------------
Main: 
    x = (x + 1) // LEDcount
    GPIO.0(x) = !!(LoopLED(x) < OnTime(x))
    LoopLED(x) = (LoopLED(x) + 1) // (OnTime(x) + OffTime(x))
    #IFDEF USE_RANDOM_SEQUENCE
        RandPeriod(x) = RandPeriod(x) - 1
        IF RandPeriod(x) = 0 THEN
            READ RandPeriods+(x<<1), WORD RandPeriod(x)
            RANDOM RND
            OnTime(x) = (MAX_ON - MIN_ON)* RND.HighByte / 255 + MIN_ON 
            OffTime(x)= (MAX_OFF - MIN_OFF)* RND.LowByte / 255 + MIN_OFF
        ENDIF
    #ENDIF
    IF x != (LEDcount - 1) THEN Main

Waiting: IF !CCPIF THEN Waiting
    CCPIF = 0
GOTO Main

Since there are no include files, my Google search didn't point to anything other than that. Is this too much to expect from a 12F?

[grahamg]

Looking at the compiler include file for a 12f683 the CCPR1 VAR WORD EXT has already been included. I think you should be able to comment this line out.
Can you please tell me what the following line of code does:
GPIO.0(x) = !!(LoopLED(x) < OnTime(x))
Cannot find any reference to !!

[Darrel Taylor]

Can you please tell me what the following line of code does:
GPIO.0(x) = !!(LoopLED(x) < OnTime(x))

It is equivelent to ...

IF LoopLED(x) < OnTime(x) THEN
    GPIO.0(x) = 1
ELSE
    GPIO.0(x) = 0
ENDIF

What you would like to do is a direct assignment of a True/False comparison to a variable.

GPIO.0(x) = LoopLED(x) < OnTime(x)

But LoopLED(x) < OnTime(x) is a "Logical" expression that can't be assigned to a BIT variable.

The bitwise NOT operator (!) can convert the logical expression to a bitwise expression that can be assigned to a BIT variable.

A single ! will invert the result, so a second ! is used to invert it back.
Somtimes you want the result inverted, and you can use a single !.
Other times you might invert the logic of the comparison, use a single !, which gives you a non-inverted result.

[RossWaddell]

Darrel - do you also think I can simply comment out this line to compile for a 12F629?

CCPR1 VAR WORD EXT : @CCPR1 = CCPR1L

[Acetronics2]

Hi,

I think you also have to add some lines very specific for the used chip ...

especially to deal with GPIO.3 ... which is input only pin ...

Alain

[RossWaddell]

I overlooked that GP3 is input only, Alain. So the 12F629 has only 5 output pins. That would still work for the 5 blinky LEDs but I've been expanding Darrel's example to include 2 other non-random blinky LEDs in order to further reduce the # of components, so if I end up with 6-7 different blink rates I might as well stay with the 16F1825 (since there doesn't appear to be any PICs with 10-12 pins).

[Jerson]

It is equivelent to ...

IF LoopLED(x) < OnTime(x) THEN
    GPIO.0(x) = 1
ELSE
    GPIO.0(x) = 0
ENDIF

Like any invention, after the explanation, it seems obvious. However, this is a coding construct I loved learning.

[Ioannis]

Cool! The man is an artist!

Kudos to Darrel.

Ioannis

[Mike, K8LH]

It is equivelent to ...

IF LoopLED(x) < OnTime(x) THEN
    GPIO.0(x) = 1
ELSE
    GPIO.0(x) = 0
ENDIF

What you would like to do is a direct assignment of a True/False comparison to a variable.

GPIO.0(x) = LoopLED(x) < OnTime(x)

But LoopLED(x) < OnTime(x) is a "Logical" expression that can't be assigned to a BIT variable.

The bitwise NOT operator (!) can convert the logical expression to a bitwise expression that can be assigned to a BIT variable.

A single ! will invert the result, so a second ! is used to invert it back.
Somtimes you want the result inverted, and you can use a single !.
Other times you might invert the logic of the comparison, use a single !, which gives you a non-inverted result.

Could the comparison have been reversed, like this?

GPIO.0(x) = !(LoopLED(x) >= OnTime(x))

Also, is the GPIO.0(x) a valid PBP construct? It's not very intuitive (to me). I would think that GPIO.0 is the GP0 pin and then the (x) looks really alien...

[Darrel Taylor]

Thanks guys, but I learned the !! from Charles Leo (my boss).
It's great to be in the offices of melabs.

Mike,

Yup, that's the correct way to "invert the logic of the comparison, use a single !, which gives you a non-inverted result.".

And while it does look strange, the (x) in GPIO.0(x) is the offset from GPIO.0.
If x = 0 then it uses GPIO.0
If x = 2, it uses GPIO.2

You can start from any bit.
With GPIO.2(x)

If x = 0 then it uses GPIO.2
If x = 2, it uses GPIO.4

This notation can only be used in direct assignments (using = sign).
You cannot use it as PIN designators in PBP commands like SERIN/OUT, HIGH/LOW etc.

[RossWaddell]

No argument from me, SteveB - the elegance of the solution is indeed beautiful!

Would I gain any better resolution/exactitude of timings by increasing the oscillator? The 16F1825 can go up to 32Mhz internal with the pullup enabled. I've added to Darrel's solution to include another blinky without randomization of the periods, so it needs to be on for 20ms and off for 480ms (i.e. it blinks twice a second).

[SteveB]

My god ... it's ... it's beautiful

Yes, the code is beautiful (can speak for the lights, but I'm sure their nice too).

Have you seen one of Darrel's breadbord layouts? Those are equally as beautiful.