Single PIC to Blink 5 LEDs Independently?

**RossWaddell** · - 26th January 2013, 00:47

Originally Posted by wdmagic

you can do that easily if you want them all to dim at the same rate using the PICs PWM going into the gate of a seperate FET with its drain tied to all the fets, sources. and its source to ground, this adds a ~.5v voltage drop but you can compensate by adjusting your pots.

I did this on a guys truck, he wanted 2 sets of floorboard lights, operated from a single pushbutton, but he also wanted to control their brightness, it was easy enought to set a 2 bit binary output to 2 FETS, and have them tied to a 3rd FET that was drivin by the PWM pin. and I just used a POT to set the PWM, and a button to select the lights (left, right, both, off).

But did the LEDs blink? It sounds like your LEDs were steady-on with brightness control. For my application, I need to control the brightness of blinking LEDs. You can see the full code file above (created by Darrel) but I think the relevant portion is:

Code:

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

;----[Initialize on/off periods & random sequencing (if enabled)]---------------
;    (only randomize first 5 blinkies; 6th is strobe which must remaing constant)
;    (running lights (7th) are set up separately)
FOR x = 0 to (LEDcount - 2)           ; Load the periods from EEPROM
    READ OnTimes+x, OnTime(x)
    READ OffTimes+x, OffTime(x)
    #IFDEF USE_RANDOM_SEQUENCE
        IF x < 5 THEN
            READ RandPeriods+(x<<1), WORD RandPeriod(x)
        ENDIF
    #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

;----[Main Program Loop]----------------------------------------
Main: 
    ' Check if flash mode has changed
    IF FlashMode <> Old_FlashMode Then
        Old_FlashMode = FlashMode
        GOSUB SetNavLtsFlashRates
    EndIF 

    x = (x + 1) // LEDcount
    PORTB.1(x) = !!(LoopLED(x) < OnTime(x))
    LoopLED(x) = (LoopLED(x) + 1) // (OnTime(x) + OffTime(x))
    #IFDEF USE_RANDOM_SEQUENCE
        IF x < 5 THEN
            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
    #ENDIF
    IF x != (LEDcount - 1) THEN Main

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

**RossWaddell** · - 26th March 2014, 01:39

(Reviving an old thread)

I now need to simplify this a bit and put this on a 8-pin PIC. I need 5 blinkies so I'd like to use a 12F629 (knowing GP3/MCLR is input only, I'll use GP0-GP5 and if nothing happens on GP3 then that's fine).

The code won't compile because of this part:

Code:

;-- 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

These registers exist on a 16F690 (and others) but not 12F629. I had earlier tried a 12F683 (my go-to PIC) but the .inc file for it already has a define for CCPR1 so I'd have to comment out that line in the .inc file but that makes me a wee bit uncomfortable.

Is there a way to make this work on a 12F690 or 12F683? If not, is there another 8-pin PIC I could use? I need to be able to find SMT packages as the space where the PCB is going is extremely tight (I've never soldered SMTs before so that should be fun).

Here's the whole code:

Code:

'****************************************************************
'*  Name    : Nacelle_Blinking_Lights_5_12F629_4Mhz_Int.pbp     *
'*  Author  : Ross A. Waddell                                   *
'****************************************************************


' For production version of this code, update config fuses to 
' enable code protect on

' Basic blinky code provided by Darrel Taylor
' See forum posting here:
' http://www.picbasic.co.uk/forum/showthread.php?t=17299&p=116934#post116934

' ***************************************************************
' Pin Connections
' ***************************************************************

' GP5    -> pin 2             -> R4 -> BL4
' GP4    -> pin 3             -> R5 -> BL5
' GP3    -> pin 4             -> MCLR (input only, 'dummy' BL6)
' GP2    -> pin 5             -> R1 -> BL1
' GP1    -> pin 6             -> R2 -> BL2
' GP0    -> pin 7             -> R3 -> BL3

' ***************************************************************
' Initialization
' ***************************************************************

DEFINE OSC 4             ' Set oscillator 4Mhz

DEFINE BLINKYFREQ 100    ' 10mS periods

CMCON    = %0000111	     'Turn off comparators
TRISIO   = %00000000	 'Make all GPIO pins output

' ***************************************************************
' 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 & _BODEN_ON & _CP_OFF & _CPD_OFF
#ENDCONFIG

LEDcount    CON 6            ; Number of blinking LEDs
                             ; (includes 'fummy' LED on GP3/MCLR pin, 
                             ; rates defined separately below)
                                         
'                 BL3,BL2,BL1,BL6,BL5,BL4
'                 --- --- --- --- --- ---
' default "on" periods for each output
OnTimes     DATA  50 ,82 ,50 ,33 ,133, 2
' default "off" periods for each output
OffTimes    DATA 150 ,45 ,50 ,33 ,22 ,48

;----------------------------------------------------------------
#DEFINE USE_RANDOM_SEQUENCE           ; comment for contiuous Sequence
#IFDEF USE_RANDOM_SEQUENCE            
    RND     VAR WORD : RND = 13864
    MIN_ON  CON 33                    ; Minimum random ON time
    MAX_ON  CON 100                   ; Maximum random ON time
    MIN_OFF CON 33                    ; 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 500, WORD 2000, 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 on/off periods & random sequencing (if enabled)]---------------
FOR x = 0 to (LEDcount)           ; Load the periods from EEPROM
    READ OnTimes+x, OnTime(x)
    READ OffTimes+x, OffTime(x)
    #IFDEF USE_RANDOM_SEQUENCE
        IF x < 5 THEN
            READ RandPeriods+(x<<1), WORD RandPeriod(x)
        ENDIF
    #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

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

**Darrel Taylor** · - 26th March 2014, 03:12

The 12F629 doesn't have a CCP module.
You'll be better off with the 12F683.

Don't comment the CCPR1 line in the .inc file. Comment the one in the blinky code.

Code:

CCPR1         VAR WORD EXT : @CCPR1 = CCPR1L

**Amoque** · - 26th March 2014, 03:34

You might also, if I follow your intent, use an AND gate to combine PWM and I/O into one PWM modulated blinking output.

**RossWaddell** · - 26th March 2014, 19:34

Originally Posted by Amoque

You might also, if I follow your intent, use an AND gate to combine PWM and I/O into one PWM modulated blinking output.

Presumably I'd need 5 AND gates for the 5 outputs, right? and then connect the other input of each AND gate to a PWM from another chip?

**RossWaddell** · - 26th March 2014, 11:38

Originally Posted by Darrel Taylor

The 12F629 doesn't have a CCP module.
You'll be better off with the 12F683.

Don't comment the CCPR1 line in the .inc file. Comment the one in the blinky code.

Code:

CCPR1         VAR WORD EXT : @CCPR1 = CCPR1L

Thanks Darrel!

**RossWaddell** · - 27th March 2014, 03:01

Originally Posted by Darrel Taylor

The 12F629 doesn't have a CCP module.
You'll be better off with the 12F683.

Don't comment the CCPR1 line in the .inc file. Comment the one in the blinky code.

Code:

CCPR1         VAR WORD EXT : @CCPR1 = CCPR1L

I converted the code to use a 12F683 PIC but the LEDs come on and then stay on (although not all 5; some stay off). Is it because of the input-only GP4/MCLR?

Code:

' Basic blinky code provided by Darrel Taylor
' See forum posting here:
' http://www.picbasic.co.uk/forum/showthread.php?t=17299&p=116934#post116934

' ***************************************************************
' Pin Connections
' ***************************************************************

' GP5    -> pin 2             -> R4 -> BL4
' GP4    -> pin 3             -> R5 -> BL5
' GP3    -> pin 4             -> MCLR (input only, 'dummy' BL6)
' GP2    -> pin 5             -> R1 -> BL1
' GP1    -> pin 6             -> R2 -> BL2
' GP0    -> pin 7             -> R3 -> BL3

' Initialization
' ***************************************************************

DEFINE OSC 8             ' Set oscillator 8Mhz

DEFINE BLINKYFREQ 100    ' 10mS periods

OSCCON   = %0111
CMCON0   = %0000111	     ' Turn off comparators
ANSEL.0  = 0             ' Digital only
ANSEL.1  = 0             ' Digital only
ANSEL.2  = 0             ' Digital only
ANSEL.3  = 0             ' Digital only
ADCON0.0 = 0             ' ADC is disabled
TRISIO   = %00000000	 ' Make all GPIO pins output

' ***************************************************************
' 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

LEDcount    CON 6            ; Number of blinking LEDs
                             ; (includes 'fummy' LED on GP3/MCLR pin, 
                             ; rates defined separately below)
                                         
'                 BL3,BL2,BL1,BL6,BL5,BL4
'                 --- --- --- --- --- ---
' default "on" periods for each output
OnTimes     DATA  50 ,82 ,50 ,33 ,133, 2
' default "off" periods for each output
OffTimes    DATA 150 ,45 ,50 ,33 ,22 ,48

;----------------------------------------------------------------
#DEFINE USE_RANDOM_SEQUENCE           ; comment for contiuous Sequence
#IFDEF USE_RANDOM_SEQUENCE            
    RND     VAR WORD : RND = 13864
    MIN_ON  CON 33                    ; Minimum random ON time
    MAX_ON  CON 100                   ; Maximum random ON time
    MIN_OFF CON 33                    ; 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 500, WORD 2000, 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 on/off periods & random sequencing (if enabled)]---------------
FOR x = 0 to (LEDcount)           ; 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

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

**Darrel Taylor** · - 27th March 2014, 03:53

On the 12F683, the CCP1IF bit is PIR1.5.
Why they have to change things all the time ... I don't know.

Code:

CCPIF         VAR PIR1.5

Both the OSCCON and CMCON0 values don't have enough digits.
added: CMCON0 won't matter cause it's still 7, but to keep things consistent ...

Code:

OSCCON   = %01110000        ' 8Mhz
CMCON0   = %00000111	    ' Turn off comparators

Not sure how this got changed, it should be ...

Code:

FOR x = 0 to (LEDcount - 1)           ; Load the periods from EEPROM

**Amoque** · - 27th March 2014, 12:36

Again, not wholly sure what your trying to do... I have trouble following someone else's code (even my own sometimes), but a PWM output tied to one input of each (yes, 5) "AND" gate, the other input to each I/O. Toggling I/O then controls modulated output. I am thinking of IR communications where a serial data stream and 38K PWM are "ANDed" for IR transmission.

**RossWaddell** · - 27th March 2014, 14:33

Originally Posted by Amoque

Again, not wholly sure what your trying to do... I have trouble following someone else's code (even my own sometimes), but a PWM output tied to one input of each (yes, 5) "AND" gate, the other input to each I/O. Toggling I/O then controls modulated output. I am thinking of IR communications where a serial data stream and 38K PWM are "ANDed" for IR transmission.

I was initially intending to make the brightness of the LEDs controllable via PWM, but now the chips are moving off the main board to another PCB that will be buried deep within my model where they will only have +5V & GND wires. These boards are too small to add any other components (even SMTs) so I'll just have to breadboard them with various series-limiting resistors to get the right brightness.

Your suggestion is something I will investigate for the rest of my circuit where I do intend to provide brightness control on the main board. Right now, I'm daisy-chaining 2 NPNs which someone on SparkFun suggested but I haven't breadboarded it yet to see if it works.

**RossWaddell** · - 27th March 2014, 14:29

Originally Posted by Darrel Taylor

On the 12F683, the CCP1IF bit is PIR1.5.
Why they have to change things all the time ... I don't know.

Code:

CCPIF         VAR PIR1.5

Both the OSCCON and CMCON0 values don't have enough digits.
added: CMCON0 won't matter cause it's still 7, but to keep things consistent ...

Code:

OSCCON   = %01110000        ' 8Mhz
CMCON0   = %00000111	    ' Turn off comparators

Not sure how this got changed, it should be ...

Code:

FOR x = 0 to (LEDcount - 1)           ; Load the periods from EEPROM

Thank you SOOOO much, Darrel!

BTW, what software is that you are using to test out the code?

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