Charlie-plexing

[Demon]

The need to control a lot of LEDs arose in my residential alarm project, the most efficient I could google was charlie-plexing. I thought I'd share a chart showing combinations:

EDIT: MUST USE 1 RESISTOR PER PIN



Robert


Reference: http://ww1.microchip.com/downloads/e...Doc/40040b.pdf

EDIT: Even better reference courtesy of Charlie, clearly explains the technique:
http://www.instructables.com/id/Char...s--The-theory/

Skip down to working code and videos:
http://www.picbasic.co.uk/forum/show...132#post130132

[Amoque]

As I study what is clearly an amazing example, many thoughts come to mind...

"There is only one step from the sublime to the ridiculous." - Napoleon Bonaparte.

Stay tuned for Robert's forthcoming book: "Burglary with a Light Show"

A subtitle: Redundancy in redundant lighting systems .

While I jest, I do so in fun. I am... I search for an adjective... somehow "flabbergasted" seems appropriate. You are controlling nearly what could be, an entire string of holiday lights, with 10 pins!

Thanks for sharing!

[towlerg]

And the real beauty is that unlike multiplexing you don't have to constantly service the array just set the inputs and outputs and write once to the outputs. Good example Demon.

George

[Demon]

Congratulate me once I get mine working. LOL

Robert

[Charlie]

Hi Robert - a couple questions / thoughts....
I think you have too many resistors. With the original Charlie-plexing, there should be one current limiter per pin, not per diode, since some combinations rely on the forward volt drop of a diode to keep two others from coming on. I think what you did will work, but once you get beyond 3 pins, you may start having different intensities of LEDs. It would certainly save you some components to go per pin rather than per LED pair.
Do the red and green diodes have the same volt drop? Green is usually about double red, so there will be still more challenges. Is it your intent that something is green or red, but never off unless broken? I think that might be difficult to do too. The array will need to be constantly scanned if more than one led should be on at any given time. But you'll want to do that to save power, anyway.
Have you done a big truth table to see what happens for each combination? You'll need that to write the code anyway, but it might save you a lot of work. I don't think this is something that can be tested in a simulator easily since it depends on analogue effects.
Anyway, very cool approach if you can work around those limitations!

[Demon]

Charlie! We were just talking about you.

Hi Robert - a couple questions / thoughts....
I think you have too many resistors. With the original Charlie-plexing, there should be one current limiter per pin, not per diode, since some combinations rely on the forward volt drop of a diode to keep two others from coming on. I think what you did will work, but once you get beyond 3 pins, you may start having different intensities of LEDs. It would certainly save you some components to go per pin rather than per LED pair.

Many LEDs on the same pin may be on, but only a single LED per pair can be lit.

The tri-state properties of a pin control which LED is lit, not forward voltage drop. See Tip #2 in the Microchip PDF.

LED intensity is not supposed to vary depending on active LEDs.

Do the red and green diodes have the same volt drop? Green is usually about double red, so there will be still more challenges.

Probably not, the LEDs I have in stock do not have identical properties. But they are close enough for personal use. I am compensating by using different light intensities; ie: I have varying intensities of LEDs for the same colour. Bulk purchases so I don't have specs.

Is it your intent that something is green or red, but never off unless broken? I think that might be difficult to do too.

I don't understand.

The array will need to be constantly scanned if more than one led should be on at any given time. But you'll want to do that to save power, anyway.

Yes, definitely scanning to save current.

Have you done a big truth table to see what happens for each combination? You'll need that to write the code anyway, but it might save you a lot of work.

Next on my TO-DO list.

I don't think this is something that can be tested in a simulator easily since it depends on analogue effects.
Anyway, very cool approach if you can work around those limitations!

Yes it can be tested, this is digital only. But I don't have Proteus.

Robert

[towlerg]

Here one I made earlier

Actually simulated, it's the display of a tidal state indicator that one day I'll get round to building. The Xylon effect is just to test all bits with the two elements separate.

George

N2 does work, just a slightly dodgy GIF

[Demon]

Charlie, about the red-or-green-or-broken question. I can light the red, green or nothing at all if I wish (which is possible in this application).

I am powering only one pin at a time. Due to the interconnections on the matrix, applying power to more than one pin will have undesired results.

Pass 1:
"1" on pin 1, "0" on pin 2, Input remaining pins lights the top left red LED.

Pass 2:
"1" on pin 4, "0" on pin 3, Input remaining pins lights the top green LED between pins 3 and 4.

But...

Pass 3:
"1" on pin 1, "0" on pin 2,
"1" on pin 4, "0" on pin 3, Input remaining pins lights the top left red LED and the top green LED between pins 3 and 4,
but it also lights
a red LED between pins 1 and 3 and
a green LED between pins 4 and 2
since those circuits are also completed unintentionally.

Robert

[Demon]

...Actually simulated, it's the display of a tidal state indicator that one day I'll get round to building. The Xylon effect is just to test all bits with the two elements separate.

George

Either you messed up recording your GIF, or there's a bug in the top row.

And it's Cylon.

Robert



EDIT: It might also be an Internet Explorer thing, I'm still on XP on my laptop.

[Demon]

I can power pin 1:


I can power pin 4:


But I can't do the same thing at the same time, two unwanted LEDs come on:

Edit: I just noticed I missed another unwanted LED between pins 4 and 2.

I'll probably use a dedicated 18F24K22 running at 64MHz to manage the LEDs. I have to test, but blinking each LED individually might give enough persistence of vision (50 Hz or so).

I was initially planning on powering all LEDs active on one pin, but that might complicate things beyond my limitted abilities. I like to keep things simple.

I might also manage a simple keypad, not sure yet. I have enough pins, but tests will show how much the PIC can manage and still give satisfactory visual effects.

Robert

[Demon]

As I sit down to think how to manage this, one MAJOR drawback:

You had better not forget any LEDs on your project 'cause adding one later is going to be "troublesome".

You can always add it at the bottom of your truth table, but I'm the obsessive compulsive type that likes symetry; LEDs are handled in the logic as they are placed on the circuit board. Remnants of hating spaghetti code on mainframes (COBOL + GOTO = NIGHTMARES).

Robert

[Demon]

Some neat stuff I forgot that I found several years ago on Charlie-plexing.

clear
define osc4
cmcon0=7
ansel=0
adcon0 = 0
@ device mclr_off
@ device wdt_off
@ device bod_off
@ device cpd_off
@ device protect_off

led var byte
ledstates var byte
trisstate var byte
delay var word
noghost var byte
gpnoghost var byte

noghost= %111111
delay= 1500

starthere:
gpio.3 = 0
if gpio.3 = 1 then
  goto main
endif
goto starthere

main:
for led = 1 to 6
  select case led
    case 0 : ledstates =%001 : trisstate =%100
    case 1 : ledstates =%010 : trisstate =%100
    case 2 : ledstates =%001 : trisstate =%010
    case 3 : ledstates =%100 : trisstate =%010
    case 4 : ledstates =%100 : trisstate =%010
    case 5 : ledstates =%010 : trisstate =%001
    case 6 : ledstates =%100 : trisstate =%001
  end select
  trisio = noghost
  gpio = ( gpio & %111000) | ledstates
  trisio = (trisio & %111000) | trisstate
  pause delay
next led

for led = 1 to 5
  select case led
    case 1 : ledstates =%000001: trisstate =%101110
    case 2 : ledstates =%011000: trisstate =%101110
    case 3 : ledstates =%000010: trisstate =%101101
    case 4 : ledstates =%010000: trisstate =%101101
    case 5 : ledstates =%000010: trisstate =%011101
  end select
  trisio = noghost
  gpio = ( gpio & %111000) | ledstates
  trisio = (trisio & %111000) | trisstate
  pause delay
next led

trisio=noghost
gpio=gpnoghost

goto starthere
end

Editted to add some colour, original was black on light gray background.

I wish I could give a link and credit, but I can't find anything on google for this now (been looking for over an hour).

Robert

[AvionicsMaster1]

Did this a while ago. Don't know if it will help. http://www.picbasic.co.uk/forum/showthread.php?t=14220

If you use the above program you'll need to change you define osc line.

Good luck.

[Demon]

I used the wiring above for pins D.1, D.2 and D.3 on a 16F877 and it didn't work as expected.

I get 3 LEDs blinking faintly instead of a single one. It seems as if the current loops over to the unused pin and comes back.

I'll have to check out your thread. I must be missing something.

' Blink 6 LEDs connected to Port D.1, D.2 and D.3 in charlie-plex manner

'   PIC             16F877      ext osc 20MHz
'   PBP             v2.60c
'   MPASM           v5.49
'   MCS+            v2.1.0.7
'   U2 programmer   v4.32

asm
 __config _HS_OSC & _WDT_OFF & _PWRTE_OFF & _BODEN_ON & _LVP_OFF & _CPD_OFF & _WRT_OFF & _DEBUG_OFF & _CP_OFF
endasm

DEFINE OSC 20
ADCON1 = 7                  ' Set Ports to digital
TRISA = %00000000           ' Set all Ports to output 
TRISB = %00000000
TRISC = %00000000
TRISD = %00000000
TRISE = %00000000
PORTA = %00000000           ' Set ports OFF
PORTB = %00000000
PORTC = %00000000
PORTD = %00000000
PORTE = %00000000
    pause 100
mainloop:
    TRISD = %11111001       ' Enable pins D.1 and 2
    PORTD = %00000100       ' Turn ON pin D.2 --> D.1
    pause 500
    PORTD = %00000010       ' Turn ON pin D.1 --> D.2
    pause 500

;    TRISD = %11110101       ' Enable pins D.1 and 3
;    PORTD = %00001000       ' Turn ON pin D.3 --> D.1
;    pause 500
;    PORTD = %00000010       ' Turn ON pin D.1 --> D.3
;    pause 500

;    TRISD = %11110011       ' Enable pins D.2 and 3
;    PORTD = %00000100       ' Turn ON pin D.2 --> D.3
;    pause 500
;    PORTD = %00001000       ' Turn ON pin D.3 --> D.2
;    pause 500

    TRISD = %11111111       ' All pins disabled
    pause 500
    goto mainloop
End

Robert

[Demon]

Did this a while ago. Don't know if it will help. http://www.picbasic.co.uk/forum/showthread.php?t=14220

If you use the above program you'll need to change you define osc line.

Good luck.

LMAO!

I posted YOUR program above! I googled and searched this forum to try and find where I got it from but never found it.

I'll have to look this over again, I must miss something obvious. You have GPIO, I only see PORT and TRIS registers as relevant on a 16F877.

Robert

[Demon]

Partly fixed.

I was using 3 red, green and yellow LEDs; they have wildly different current draw/voltage drops. I switched to all greens and the ghosting effect is practically gone.

I saw your comments about ghosting and noticed you output PORT before TRIS, didn't help me; tried both ways.

Robert

EDIT:

asm
 __config _HS_OSC & _WDT_OFF & _PWRTE_OFF & _BODEN_ON & _LVP_OFF & _CPD_OFF & _WRT_OFF & _DEBUG_OFF & _CP_OFF
endasm
DEFINE OSC 20
ADCON1 = 7                  ' Set Ports to digital
TRISA = %00000000           ' Set all Ports to output 
TRISB = %00000000
TRISC = %00000000
TRISD = %00000000
TRISE = %00000000
PORTA = %00000000           ' Set ports OFF
PORTB = %00000000
PORTC = %00000000
PORTD = %00000000
PORTE = %00000000
    pause 100
mainloop:
    TRISD = %11111001       ' Enable pins D.1 and 2
    PORTD = %00000100       ' Turn ON pin D.2 --> D.1
    pause 500
    TRISD = %11111001       ' Enable pins D.1 and 2
    PORTD = %00000010       ' Turn ON pin D.1 --> D.2
    pause 500

    TRISD = %11110101       ' Enable pins D.1 and 3
    PORTD = %00001000       ' Turn ON pin D.3 --> D.1
    pause 500
    TRISD = %11110101       ' Enable pins D.1 and 3
    PORTD = %00000010       ' Turn ON pin D.1 --> D.3
    pause 500

    TRISD = %11110011       ' Enable pins D.2 and 3
    PORTD = %00000100       ' Turn ON pin D.2 --> D.3
    pause 500
    TRISD = %11110011       ' Enable pins D.2 and 3
    PORTD = %00001000       ' Turn ON pin D.3 --> D.2
    pause 500

    TRISD = %11111111       ' All pins disabled
    pause 500
    goto mainloop
End

[Demon]

Hi Robert - a couple questions / thoughts....
I think you have too many resistors. With the original Charlie-plexing, there should be one current limiter per pin, not per diode, since some combinations rely on the forward volt drop of a diode to keep two others from coming on. I think what you did will work, but once you get beyond 3 pins, you may start having different intensities of LEDs. It would certainly save you some components to go per pin rather than per LED pair.
...

Aaaaaaaand I think this just came back to bite me. LOL

Robert

[Charlie]

Hi Robert,
This article explains what I was trying to tell you about analog vs digital effects: http://www.instructables.com/id/Char...s--The-theory/
The Microchip article is a quick example, but not true Charlie-plexing, and it doesn't scale up nicely.

[Demon]

Ah perception, what a wonderful thing. When I said digital I meant the logic, and when you said analog you meant the properties of the LED. LOL

I had found that article on google but didn't see anything new at first glance and moved on. It's really a few pages deep that it gets into the meat of the matter. Excellent article though, explained everything so clearly.

I especially appreciate how he discusses making a pin input disables it. I never understood "high impedance state". It's simple, it impedes, like that 10M resistor he has on his schematic of the input pin.

It also explains why I couldn't get a decent reading on my Saleae probe; current DOES flow through the unwanted LEDs. It's just that they don't get enough current to light up; hence the importance of forward voltage drop you mentionned (he explains that clearly). It's nice understanding what's going on.

No ghosting with 200usec delay:


No pauses:


Robert

[AvionicsMaster1]

To all, I'm learning so these may be stupid questions. Please put the flamethrowers down.

Are you still using the 16F877? If so:

Does ADCON1 = 7 do anything for you? It looks like none of ADC ports are on Port D and this wouldn't effect them.

I don't think of the TRISX as setting ports to digital only setting them input or output. With the 877 are the ports already set so with a high you get 5V out and a low gives you zero when you set them as outputs?

If you're continuing to have issues with ghosting I found, on the 12F683, that setting all ports to input and turning them off before I moved on to the next light helped quite a bit.

Hope it helps.

[Demon]

To all, I'm learning so these may be stupid questions. Please put the flamethrowers down.
...

There are no stupid questions, just stupid people. Sorry, couldn't resist.

...Are you still using the 16F877?...

Yup.

...Does ADCON1 = 7 do anything for you? It looks like none of ADC ports are on Port D and this wouldn't effect them...

I use it because I have been using digital only so far. First thing I do when using a new model PIC is run with ALLDIGITAL and add whatever it tells me to. I've used a 16F877 ever since I've been here and I'm just using copies of my first program.

It just happened that I ran ALLDIGITAL again with this PIC when I started this testing and it also gave me that line to add.

...I don't think of the TRISX as setting ports to digital only setting them input or output...

Yup.

With the 877 are the ports already set so with a high you get 5V out and a low gives you zero when you set them as outputs?...

I don't know if they are analog or digital by default. I'd have to check the datasheet for ADCON1.

...If you're continuing to have issues with ghosting I found, on the 12F683, that setting all ports to input and turning them off before I moved on to the next light helped quite a bit...

Nope, no more ghosting. See video with 200uSec delay.

Robert

[Demon]

I've since moved on to 18F44K22 after the videos but the code essentially remains the same:

mainloop:

    PortD.2 = 1             ' Heartbeat

    TRISA = %11111100
    PORTA = %00000001       ' LED 1
    PAUSE 200
    PORTA = %00000010       ' LED 2
    PAUSE 200

    TRISA = %11110011
    PORTA = %00000100       ' LED 3
    PAUSE 200
    PORTA = %00001000       ' LED 4
    PAUSE 200

    PortD.2 = 0             ' Heartbeat

    TRISA = %11001111
    PORTA = %00010000       ' LED 5
    PAUSE 200
    PORTA = %00100000       ' LED 6
    PAUSE 200

    TRISA = %00111111
    PORTA = %01000000       ' LED 7
    PAUSE 200
    PORTA = %10000000       ' LED 8
    PAUSE 200

    goto mainloop
End

I don't have to set the TRIS register when I remain on the same LED pair.

[Demon]

This:

' Blink 56 LEDs connected to PORT A in charlie-plex manner

'   PIC             18F44K22    int osc 64MHz
'   PBP             v2.60c
'   MPASM           v5.49
'   MCS+            v2.1.0.7
'   U2 programmer   v4.32

asm
 __CONFIG    _CONFIG1H, _FOSC_INTIO67_1H & _PLLCFG_ON_1H & _PRICLKEN_OFF_1H & _FCMEN_ON_1H & _IESO_OFF_1H
 __CONFIG    _CONFIG2L, _PWRTEN_ON_2L & _BOREN_SBORDIS_2L & _BORV_285_2L
 __CONFIG    _CONFIG2H, _WDTEN_OFF_2H
 __CONFIG    _CONFIG3H, _CCP2MX_PORTC1_3H & _PBADEN_OFF_3H & _CCP3MX_PORTE0_3H & _HFOFST_OFF_3H & _T3CMX_PORTB5_3H & _P2BMX_PORTC0_3H & _MCLRE_EXTMCLR_3H
 __CONFIG    _CONFIG4L, _STVREN_OFF_4L & _LVP_OFF_4L & _XINST_OFF_4L & _DEBUG_OFF_4L
endasm

DEFINE OSC 64

OSCCON  = %01110000              ' OSCILLATOR CONTROL REGISTER
' bit 7 IDLEN: Idle Enable bit
'     R/W       1 = Device enters Idle mode on SLEEP instruction
'               0 = Device enters Sleep mode on SLEEP instruction
' bit 6-4 IRCF<2:0>: Internal RC Oscillator Frequency Select bits(2)
'     R/W       111 = HFINTOSC – (16 MHz)
'               110 = HFINTOSC/2 – (8 MHz)
'               101 = HFINTOSC/4 – (4 MHz)
'               100 = HFINTOSC/8 – (2 MHz)
'               011 = HFINTOSC/16 – (1 MHz)(3)
'           If INTSRC = 0 and MFIOSEL = 0:
'               010 = HFINTOSC/32 – (500 kHz)
'               001 = HFINTOSC/64 – (250 kHz)
'               000 = LFINTOSC – (31.25 kHz)
'           If INTSRC = 1 and MFIOSEL = 0:
'               010 = HFINTOSC/32 – (500 kHz)
'               001 = HFINTOSC/64 – (250 kHz)
'               000 = HFINTOSC/512 – (31.25 kHz)
'           If INTSRC = 0 and MFIOSEL = 1:
'               010 = MFINTOSC – (500 kHz)
'               001 = MFINTOSC/2 – (250 kHz)
'               000 = LFINTOSC – (31.25 kHz)
'           If INTSRC = 1 and MFIOSEL = 1:
'               010 = MFINTOSC – (500 kHz)
'               001 = MFINTOSC/2 – (250 kHz)
'               000 = MFINTOSC/16 – (31.25 kHz)
' bit 3 OSTS: Oscillator Start-up Time-out Status bit
'       R       1 = Device is running from the clock defined by FOSC<3:0> of the CONFIG1H register
'               0 = Device is running from the internal oscillator (HFINTOSC, MFINTOSC or LFINTOSC)
' bit 2 HFIOFS: HFINTOSC Frequency Stable bit
'       R       1 = HFINTOSC frequency is stable
'               0 = HFINTOSC frequency is not stable
' bit 1-0 SCS<1:0>: System Clock Select bit
'       R/W     1x = Internal oscillator block
'               01 = Secondary (SOSC) oscillator
'               00 = Primary clock (determined by FOSC<3:0> in CONFIG1H).

OSCCON2 = %00000100              ' OSCILLATOR CONTROL REGISTER 2
' bit 7 PLLRDY: PLL Run Status bit
'     R         1 = System clock comes from 4xPLL
'               0 = System clock comes from an oscillator, other than 4xPLL
' bit 6 SOSCRUN: SOSC Run Status bit
'     R         1 = System clock comes from secondary SOSC
'               0 = System clock comes from an oscillator, other than SOSC
' bit 5 Unimplemented: Read as ‘0’.
' bit 4 MFIOSEL: MFINTOSC Select bit
'     R/W=0     1 = MFINTOSC is used in place of HFINTOSC frequencies of 500 kHz, 250 kHz and 31.25 kHz
'               0 = MFINTOSC is not used
' bit 3 SOSCGO(1): Secondary Oscillator Start Control bit
'     R/W=0     1 = Secondary oscillator is enabled.
'               0 = Secondary oscillator is shut off if no other sources are requesting it.
' bit 2 PRISD: Primary Oscillator Drive Circuit Shutdown bit
'     R/W=1     1 = Oscillator drive circuit on
'               0 = Oscillator drive circuit off (zero power)
' bit 1 MFIOFS: MFINTOSC Frequency Stable bit
'     R         1 = MFINTOSC is stable
'               0 = MFINTOSC is not stable
' bit 0 LFIOFS: LFINTOSC Frequency Stable bit
'     R         1 = LFINTOSC is stable
'               0 = LFINTOSC is not stable

OSCTUNE = %11000000              ' OSCILLATOR TUNING REGISTER
' bit 7 INTSRC: Internal Oscillator Low-Frequency Source Select bit
'     R/W       1 = 31.25 kHz device clock derived from the MFINTOSC or HFINTOSC source
'               0 = 31.25 kHz device clock derived directly from LFINTOSC internal oscillator
' bit 6 PLLEN: Frequency Multiplier 4xPLL for HFINTOSC Enable bit(1)
'     R/W       1 = PLL enabled
'               0 = PLL disabled
' bit 5-0 TUN<5:0>: Frequency Tuning bits – use to adjust MFINTOSC and HFINTOSC frequencies
'     R/W       011111 = Maximum frequency
'               011110 =
'               • • •
'               000001 =
'               000000 = Oscillator module (HFINTOSC and MFINTOSC) are running at the factory calibrated frequency.
'               111111 =
'               • • •
'               100000 = Minimum frequency

ANSELA = %00000000          ' Set ports to digital
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00000000
ANSELE = %00000000

ADCON0 = %00000000          ' Disable ADC

TRISA = %00000000           ' Set all Ports to output 
TRISB = %00000000
TRISC = %00000000
TRISD = %00000000
TRISE = %00000000
PORTA = %00000000           ' Set ports OFF
PORTB = %00000000
PORTC = %00000000
PORTD = %00000000
PORTE = %00000000

varLEDstate VAR BYTE[55]
varLEDport  VAR BYTE[55]
varArray    var byte
varEEPROM   var byte

varEEPROM = 0

'-------------------------   T E M P O R A R Y   ------------------------------
for varArray = 0 to 55                      ' Location in Array
    varEEPROM = varEEPROM + 1               ' Location in EEPROM
    read varEEPROM, VARLEDstate[varArray]
    varEEPROM = varEEPROM + 1
    read varEEPROM, VARLEDport[varArray]
next varArray
'------------------------------------------------------------------------------

    pause 100

mainloop:

    for varArray = 0 to 55               ' LEDs in ascending sequence
        TRISA = VARLEDSTATE[varArray]
        PORTA = VARLEDPORT[varArray]
        PAUSE 15
    next varArray

    for varArray = 55 to 0 step -1      ' LEDs in decending sequence
        TRISA = VARLEDSTATE[varArray]
        PORTA = VARLEDPORT[varArray]
        PAUSE 15
    next varArray
 
    goto mainloop
End


DATA @1,%11111100   ' Pin A0
DATA %00000001

DATA %11111010
DATA %00000001

DATA %11110110
DATA %00000001

DATA %11101110
DATA %00000001

DATA %11011110
DATA %00000001

DATA %10111110
DATA %00000001

DATA %01111110
DATA %00000001

DATA %11111100   ' Pin A1
DATA %00000010

DATA %11111001
DATA %00000010

DATA %11110101
DATA %00000010

DATA %11101101
DATA %00000010

DATA %11011101
DATA %00000010

DATA %10111101
DATA %00000010

DATA %01111101
DATA %00000010

DATA %11111010   ' Pin A2
DATA %00000100

DATA %11111001
DATA %00000100

DATA %11110011
DATA %00000100

DATA %11101011
DATA %00000100

DATA %11011011
DATA %00000100

DATA %10111011
DATA %00000100

DATA %01111011
DATA %00000100

DATA %11110110   ' Pin A3
DATA %00001000

DATA %11110101
DATA %00001000

DATA %11110011
DATA %00001000

DATA %11100111
DATA %00001000

DATA %11010111
DATA %00001000

DATA %10110111
DATA %00001000

DATA %01110111
DATA %00001000

DATA %11101110   ' Pin A4
DATA %00010000

DATA %11101101
DATA %00010000

DATA %11101011
DATA %00010000

DATA %11100111
DATA %00010000

DATA %11001111
DATA %00010000

DATA %10101111
DATA %00010000

DATA %01101111
DATA %00010000

DATA %11011110   ' Pin A5
DATA %00100000

DATA %11011101
DATA %00100000

DATA %11011011
DATA %00100000

DATA %11010111
DATA %00100000

DATA %11001111
DATA %00100000

DATA %10011111
DATA %00100000

DATA %01011111
DATA %00100000

DATA %10111110   ' Pin A6
DATA %01000000

DATA %10111101
DATA %01000000

DATA %10111011
DATA %01000000

DATA %10110111
DATA %01000000

DATA %10101111
DATA %01000000

DATA %10011111
DATA %01000000

DATA %00111111
DATA %01000000

DATA %01111110   ' Pin A7
DATA %10000000

DATA %01111101
DATA %10000000

DATA %01111011
DATA %10000000

DATA %01110111
DATA %10000000

DATA %01101111
DATA %10000000

DATA %01011111
DATA %10000000

DATA %00111111
DATA %10000000

Scanning through 56 LEDs:


Persistence of vision, no noticeable difference (not all LEDs point directly up):


Current consumption (removed Power Indicator LED from circuit):
- all off = 11.5mA
- all on = 22.0 mA

Robert

[Demon]

Only one LED will be bright enough to be visible even though multiple paths are active at the same time, because the shortest path is the only one with enough current. All the other undesired paths share the same current; not enough to make an LED glow.

Cycling through the 56 LEDs on the 8 pins in the post above, a LED does not have enough current 7 out of 8 times:


From Step 4:

...
OK, so a current flows through LED5, current isn't flowing through LED6 because it is reverse biased (and so are LED2 and LED4)....but there is also a path for the current to take from pin A, through LED1 and LED3 isn't there? Why are these LEDs not glowing as well.

Here is the heart of the charlieplexing scheme. Indeed there is a current flowing both LED1 and LED3, however the voltage across the both of these combined is only going to be equal to the voltage across LED5. Typically they would have half the voltage across them that LED5 has. So if we have 1.9V across LED5, then only 0.95V will be across LED1 and 0.95V across LED3.

From the If/Vf curve mentioned at the beginning of this article we can see that the current at this half voltage is much much lower than 20mA.....and those LEDs will not glow visibly. This is known as current stealing.

Thus most of the current will flow though the LED we want, the most direct path through the least number of LEDs (ie one LED), rather than any series combination of LEDs.
...

http://www.instructables.com/id/Char...eory/?ALLSTEPS

Robert


(That Habs logo just "happened" to line up with the monitor.)

[Demon]

Corrected LED matrix using one resistor per pin:

[Boater]

Hi
I'm new to this Forum.
I tried to CharliePlex 12 Leds using a 16F84A and tried to use both the A and B ports but it didn't work.
Is it possible to do that?
Regards
Jim

[Boater]

Hi
I'm trying to light pairs of Leds in a 12 Led CharliePlex.
I manage to light 4 pairs with different Leds but can't get past 4 as I end up lighting Leds used in the first 4 sets.
Code
#CONFIG
__CONFIG _XT_OSC & _CP_OFF
#ENDCONFIG
'DEFINES:
define osc 10
'Initialize:
TRISA = %00000000 'Set PORTA to Output
PORTA = %00000000 'Set Ports Off
pause 1000
MAINLOOP
pause 1000
TRISA = %11110100 'Enable Pins A.0, A.1, A.3
PORTA = %00001001 'Turn on Pins A.0, A.3 (Led 2 and 9)
pause 1000
TRISA = %11110100 'Enable Pins A.0, A.1, A.3
PORTA = %00000011 'Turn on Pin A.0, A.1 (Leds 10 and 12)
pause 1000
TRISA = %11111000 'Enable Pins A.0, A.1 A.2
PORTA = %00000011 'Turn on Pins A.0, A.1 (Leds 4 and 8)
pause 1000
TRISA = %11110010 'Enable A.0, A.2, A.3
PORTA = %00001100 'Turn on A.2, A.3 (Leds 7 and 11)
pause 1000
TRISA = %11111111 'All Pins Disabled
goto MAINLOOP
end
I am using 16F84A PIC
PICkit3 programmer
Microcode Studio Plus 5
MPLAB IPE
Windows 7
Is this the norm for CharliePlex ?
Regards
Jim(Boater)

[richard]

without a schematic its a bit difficult to intrepret whats going on in your code

wired like this , i made a table on whats needed to light each led
here is an example for a pic16f1825 to light each led in sequence


Ps code in code tags is ten times easier to interpret

'****************************************************************
'*  Name    : charlieplex.pbp                                        *
'*  Author  : richard                                   *
'*  Notice  :                                *
'*          :                                *
'*  Date    :                                          *
'*  Version :    16f1825     @3.3 volts                               *
'*  Notes   :       *
'*          :              *
'*            
'****************************************************************
  
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG

DEFINE OSC 32
 
     
led var byte
tmp var byte
 
OSCCON=$70
ANSELA=0
ANSELC=0

'TRISA = 0110
'porta.0=1
'pause 4000 
'serout2 PORTA.0,84,[ "charlieplex",13,10]
   
mainloop:
    
    for led=0 to 11
        lookup led,[12,12,9,9,3,3,5,5,6,6,10,10],tmp
        TRISC = $f0|tmp
        lookup led,[ 2, 1,4,2,8,4,8,2,8,1 ,4, 1],tmp
        latC = tmp
        pause 200
    next 
goto mainloop

[Boater]

Hi Richard
Sorry not very good at the workings of the Forum, still new but still trying.
I don't have a 16f1825 pic in fact my version of MicroCode Studio does not have that PIC listed?
I copied and pasted your code into MicroCode Studio but it would not compile with Sintax errors for , OSCON $70, ANSELA = 0, ANSELC = 0, TRISC = $f0.
Tried putting a 16f877a into the pic selection with almost same result.
I thought I had attached a diagram last time so have tried again also the code in tags, I hope.
Your pin set up is in fact the same as mine just drawn slightly different.
I am trying to flash pairs of Leds and managed to flash 4 pairs but no more.
Regards
Jim

'* Name : CharliePlexing *
'* Author : Jim Hagan *
'* Notice : Copyright (c) 2016 [select VIEW...EDITOR OPTIONS] *
'* : All Rights Reserved *
'* Date : 15/06/2016 *
'* Version : *
'* Notes : Twelve Leds 2 and 2 pattern *
'* : For 16F84A *
'************************************************* ***************
#CONFIG
__CONFIG _XT_OSC & _CP_OFF
#ENDCONFIG
'DEFINES:
define osc 10
'Initialize:
TRISA = %00000000 'Set PORTA to Output
PORTA = %00000000 'Set Ports Off
pause 1000
MAINLOOP
pause 1000
TRISA = %11110100 'Enable Pins A.0, A.1, A.3
PORTA = %00001001 'Turn on Pins A.0, A.3 (Led 2 and 9)
pause 1000
TRISA = %11110100 'Enable Pins A.0, A.1, A.3
PORTA = %00000011 'Turn on Pin A.0, A.1 (Leds 10 and 12)
pause 1000
TRISA = %11111000 'Enable Pins A.0, A.1 A.2
PORTA = %00000011 'Turn on Pins A.0, A.1 (Leds 4 and 8)
pause 1000
TRISA = %11110010 'Enable A.0, A.2, A.3
PORTA = %00001100 'Turn on A.2, A.3 (Leds 7 and 11)
pause 1000
TRISA = %11111111 'All Pins Disabled
goto MAINLOOP
end

[richard]

I copied and pasted your code into MicroCode Studio but it would not compile with Sintax errors for , OSCON $70, ANSELA = 0, ANSELC = 0, TRISC = $f0.

NOT ALL PICS ARE EQUAL , some study of the data sheet is always reccomended

your code is posted in Quote tags not code tags [#]


try this for a 16f84a

'****************************************************************
'*  Name    : charlieplex.pbp                                        *
'*  Author  : richard                                   *
'*  Notice  :                                *
'*          :                                *
'*  Date    :                                          *
'*  Version :    16f84A                                   *
'*  Notes   :       *
'*          :              *
'*            
'****************************************************************
#CONFIG
cfg = _XT_OSC
cfg&= _WDT_ON
cfg&= _PWRTE_OFF
cfg&= _CP_OFF
  __CONFIG cfg
#ENDCONFIG
 define osc 10
led var byte
tmp var byte

  
' tris     port     t,p
'1 1100 0010    12,2
'2 1100 0001    12,1
'3 1001 0100    9,4 
'4 1001 0010    9,2
'5 0011 1000    3,8
'6 0011 0100    3,4
'7 1010 0100    10,4
'8 1010 0001    10,1
'9 0101 1000    5,8
'10 0101 0010    5,2
'11 0110 1000    6,6
'12 0110 0001    6,1
 
   
mainloop:
    
    for led=0 to 11
        lookup led,[12,12,9,9,3,3,10,10,5,5,6,6],tmp
        TRISA = $f0|tmp
        lookup led,[ 2, 1,4,2,8,4, 4, 1,8,2,6,1],tmp
        PORTA = tmp
        pause 200
    next 
goto mainloop

[richard]

i see the problem

TRISA = %11110100 'Enable Pins A.0, A.1, A.3
PORTA = %00001001 'Turn on Pins A.0, A.3 (Led 2 and 9)

TRISA = %11110100 == bad
you can only light 1 led at a time , only two pins can be outputs at any one time (one high one low) the others need to be in a high impedence state [not high - high impedence ie input]

to simulate multiple lit leds the the charlieplex needs to be driven multiplex style

'****************************************************************
'*  Name    : charlieplex.pbp                                        *
'*  Author  : richard                                   *
'*  Notice  :                                *
'*          :                                *
'*  Date    :                                          *
'*  Version :    16f84A                                   *
'*  Notes   :       *
'*          :              *
'*            
'****************************************************************
#CONFIG
cfg = _XT_OSC
cfg&= _WDT_ON
cfg&= _PWRTE_OFF
cfg&= _CP_OFF
  __CONFIG cfg
#ENDCONFIG
 define osc 10
led var byte
tmp var byte

  
' tris port
'1 1100 0010    12,2
'2 1100 0001    12,1
'3 1001 0100    9,4 
'4 1001 0010    9,2
'5 0011 1000    3,8
'6 0011 0100    3,4
'7 1010 0100    10,4
'8 1010 0001    10,1
'9 0101 1000    5,8
'10 0101 0010    5,2
'11 0110 1000    6,6
'12 0110 0001    6,1
 
   
mainloop:
    
    for led=0 to 11
        lookup led,[12,12,9,9,3,3,10,10,5,5,6,6],tmp
        TRISA = $f0|tmp
        lookup led,[ 2, 1,4,2,8,4, 4, 1,8,2,6,1],tmp
        PORTA = tmp
        pause 200
    next 
    
;leds 2,9
   tmp=255
while tmp
    TRISC = $f0|12
    latC = 1
    pause 10
    TRISC = $f0|5
    latC = 8
    pause 10
    tmp=tmp-1
 wend
 
;leds 10,12 
    tmp=255
while tmp
    TRISC = $f0|5
    latC = 2
    pause 10
    TRISC = $f0|1
   latC = 1
    pause 10
    tmp=tmp-1
 wend
 
;leds 4,8
   tmp=255
while tmp
    TRISC = $f0|9
    latC = 2
    pause 10
    TRISC = $f0|10
    latC = 1
    pause 10
    tmp=tmp-1
 wend
 
;leds 7,11 
    tmp=255
while tmp
    TRISC = $f0|10
    latC = 4
    pause 10
    TRISC = $f0|6
    latC = 6
    pause 10
    tmp=tmp-1
 wend 
 
     
    
goto mainloop

[Boater]

Hi Richard
Thanks for the information. Your first program works just fine except that Led 11 does not light. I ran my 12 Led running program and all leds lit up. In your second one you only appear to light 4 pairs out of the 6 available,the same 4 pairs that I can light up so is it not possible to light 6 pairs?
My program does work but I could not find a way to light all six pairs in that 12 led set up.
I think the reason I can't compile your original program is because my PBP3 Silver only does Mid range PICS, so I need to upgrade to Gold.
Sorry I sent two drawings, slip of the mouse finger.
I will try and run this last program you sent and see what happens.
Not able to understand your first program fully, the small one, but I'm trying.
Regards
Jim

[richard]

In your second one you only appear to light 4 pairs out of the 6 available,the same 4 pairs that I can light up so is it not possible to light 6 pairs?

by using multiplexing you can " light' any or even all the leds its all about persistence of vision

to light them all

mainloop:

for led=0 to 11
lookup led,[12,12,9,9,3,3,10,10,5,5,6,6],tmp
TRISA = $f0|tmp
lookup led,[ 2, 1,4,2,8,4, 4, 1,8,2,6,1],tmp
PORTA = tmp
pauseus 1200
next
goto mainloop

[richard]

led 11 failed cause i had a typo and did not convert from my setup to yours properly , sorry

'****************************************************************
'*  Name    : charlieplex.pbp                                        *
'*  Author  : richard                                   *
'*  Notice  :                                *
'*          :                                *
'*  Date    :                                          *
'*  Version :    16f84A                                   *
'*  Notes   :       *
'*          :              *
'*            
'****************************************************************
#CONFIG
cfg = _XT_OSC
cfg&= _WDT_ON
cfg&= _PWRTE_OFF
cfg&= _CP_OFF
  __CONFIG cfg
#ENDCONFIG
 define osc 10
led var byte
tmp var byte

  
' tris port
'1 1100 0010    12,2
'2 1100 0001    12,1
'3 1001 0100    9,4 
'4 1001 0010    9,2
'5 0011 1000    3,8
'6 0011 0100    3,4
'7 1010 0100    10,4
'8 1010 0001    10,1
'9 0101 1000    5,8
'10 0101 0010    5,2
'11 0110 1000    6,4   '   typo here
'12 0110 0001    6,1
 
   
mainloop:
    
    for led=0 to 11
        lookup led,[12,12,9,9,3,3,10,10,5,5,6,6],tmp
        TRISA = $f0|tmp
        lookup led,[ 2, 1,4,2,8,4, 4, 1,8,2,4,1],tmp   ;  and here
        PORTA = tmp
        pause 200
    next 
    
;leds 2,9
   tmp=255
while tmp
    TRISA = $f0|12    ;  and here
    porta = 1    ;  and here
    pause 10
    TRISA = $f0|5    ;  and here
    porta = 8    ;  and here
    pause 10
    tmp=tmp-1
 wend
 
;leds 10,12 
    tmp=255
while tmp
    TRISa = $f0|5    ;  and here
    porta = 2    ;  and here
    pause 10
    TRISa= $f0|1    ;  and here
   porta = 1    ;  and here
    pause 10
    tmp=tmp-1
 wend
 
;leds 4,8
   tmp=255
while tmp
    TRISa= $f0|9    ;  and here
    porta = 2    ;  and here
    pause 10
    TRISa = $f0|10    ;  and here
    porta = 1    ;  and here
    pause 10
    tmp=tmp-1
 wend
 
;leds 7,11 
    tmp=255
while tmp
    TRISa= $f0|10    ;  and here
    porta = 4    ;  and here
    pause 10
    TRISa = $f0|6    ;  and here
    porta = 4    ;  and here
    pause 10
    tmp=tmp-1
 wend 
 
     
    
goto mainloop

[Boater]

Hi Richard
No problem I managed to correct it and also the two in your pairs section.
I thought they were deliberate to make me work HaHa.

'****************************************************************
'*  Name    : charlieplex.pbp                                        *
'*  Author  : richard                                   *
'*  Notice  :                                *
'*          :                                *
'*  Date    :                                          *
'*  Version :    16f84A                                   *
'*  Notes   :       *
'*          :              *
'*            
'****************************************************************
#CONFIG
cfg = _XT_OSC
cfg&= _WDT_ON
cfg&= _PWRTE_OFF
cfg&= _CP_OFF
  __CONFIG cfg
#ENDCONFIG
 define osc 10
led var byte
tmp var byte

  
' tris port
'1 1100 0010    12,2
'2 1100 0001    12,1
'3 1001 0100    9,4 
'4 1001 0010    9,2
'5 0011 1000    3,8
'6 0011 0100    3,4
'7 1010 0100    10,4
'8 1010 0001    10,1
'9 0101 1000    5,8
'10 0101 0010    5,2
'11 0110 1000    6,8
'12 0110 0001    6,1
 
   
mainloop:
    
    for led=0 to 11
        lookup led,[12,12,9,9,3,3,10,10,5,5,6,6],tmp
        TRISA = $f0|tmp
        lookup led,[ 2, 1,4,2,8,4, 4, 1,8,2,8,1],tmp
        PORTA = tmp
        pause 400
    next
    for led = 0 to 11
        lookup led,[12,9,3,10,5,6,6,5,10,3,9,12],tmp
        TRISA = $f0|tmp
        lookup led,[ 2,4,8, 4, 8,8,1,2,1,4,2,1],tmp
        PORTA = tmp
        pause 400
    next 
    
;leds 2,9
   tmp=255
while tmp
    TRISA = $f0|12
    PORTA = 1
    pause 5
    TRISA = $f0|5
    PORTA = 8
    pause 5
    tmp=tmp-1
 wend
 
;leds 10,12 
    tmp=255
while tmp
    TRISA = $f0|5
    PORTA = 2
    pause 5
    TRISA = $f0|6
    PORTA = 1
    pause 5
    tmp=tmp-1
 wend
 
;leds 4,8
   tmp=255
while tmp
    TRISA = $f0|9
    PORTA = 2
    pause 5
    TRISA = $f0|10
    PORTA = 1
    pause 5
    tmp=tmp-1
 wend
 
;leds 7,11 
    tmp=255
while tmp
    TRISA = $f0|10
    PORTA = 4
    pause 5
    TRISA = $f0|6
    PORTA = 8
    pause 5
    tmp=tmp-1
 wend 
goto mainloop

Hope you can run the above.
I do have a problem with one of the three columns.
I'm okay with the TRISA and PORTA columns but I am having difficulty sorting the 3rd one t, p.
Some of the numbers fall okay with regard to tris and port but others do not. I must be looking at it wrong.
I am presuming the t stands for tris and p for port, am I right?
Regards
Jim

[richard]

led__tris____port___ t______p
1___1100___0010__12__,__ 2

yes t and p are tris and port in decimal form for us humans

i can't run your code exactly my setup is wired differently to yours and different to my drawing too it appears
hence my muddled led 11 , any of the others may may be mislabled also . i was just happy to get the leds lit up , its to jumbled up to rework it.


i have never tried charlieplexing before, looks like the leds need to lit 15 to 20 at least times per second to minimise flicker. i was going to try a 4x4x4 charlieplex led cube but i'm having doubts now about driving 64 leds @ 20hz and having enough cpu time left to do anything else without using a pic18

[Boater]

by using multiplexing you can " light' any or even all the leds its all about persistence of vision

to light them all

Hi Richard
Just ran that short piece of code. All the Leds are lit.
It appears to be down to one line

pauseus 1200

So pausing the code for 1.2 milliseconds makes them look like they are all on?
Regards
Jim

[AvionicsMaster1]

Couple of things. In your schematic I don't see any current limiting resistors at each pin. They are necessary. When defining the oscillator speed osc needs to be OSC. I think the spaces in your lookup table are some of the problem. Try removing them and see what happens.

[Boater]

Hi AvionicsMaster1
The schematic is not really a schematic just a drawing to sort out the CharliePlex. There are 100 Ohm resistors on each pin.
The spaces in the lookup didn't seem to make any difference to the running of the program but I will try it without them.
Almost all of the code is from Richard and even with very slight errors i am finding it very instructive.
thankyou for your observations
regards
Jim

So Richard when I see 12 in the t,p column I am really looking at TRIS or PORT 1100 and 7 will be 0111 ?
Regards
Jim

[richard]

So Richard when I see 12 in the t,p column I am really looking at TRIS or PORT 1100 and 7 will be 0111 ?

yes the tris and port columns are binary 0b1100=0xC = 12 or pbp parlance %1100=$c=12

this is where i was heading for the led cube , current irq rate is 1000 Hz to drive 64 leds that needs to 5 times faster
this codes flashes all the odd leds for 1 sec and then all the evens then repeats

'****************************************************************
'*  Name    : charlieplex.pbp                                        *
'*  Author  : richard                                   *
'*  Notice  :                                *
'*          :                                *
'*  Date    :                                          *
'*  Version :    16f1825     @3.3 volts                               *
'*  Notes   :       *
'*          :              *
'*            
'****************************************************************
  
#CONFIG
             __config        _CONFIG1,    _FOSC_INTOSC & _CP_OFF & _WDTE_ON  &  _PWRTE_ON  &  _MCLRE_ON  & _CLKOUTEN_OFF
              __config      _CONFIG2, _PLLEN_ON & _LVP_OFF
#ENDCONFIG

DEFINE OSC 32
 
 include "dt_ints-14.bas"
 Include "REENTERPBP.bas"
 

asm      
INT_LIST macro     
      INT_HANDLER TMR1_INT, _TOCK, PBP ,YES
      
      endm
       INT_CREATE
ENDASM       
      
       
   
     
@timer1 =TMR1L
leds var word
tmp var byte
x var byte
timer1         VAR WORD EXT
timer1=15543
T1CON=$31
@ INT_ENABLE  TMR1_INT
OSCCON=$70
ANSELA=0
ANSELC=0

   
mainloop:
leds=1365    
pause 1000 
leds=2730
pause 1000  
goto mainloop  
 
   
    
     
  
TOCK:
T1CON.0=0
timer1=timer1+64536
T1CON.0=1
if leds.0[x] then
    lookup x,[12,12,9,9,3,3,5,5,6,6,10,10],tmp
    TRISC =(TRISC&$f0)|tmp
    lookup x,[ 2, 1,4,2,8,4,8,2,8,1 ,4, 1],tmp
    latC =(latC&$f0)|tmp
endif
x=x+1
if x=12 then x=0
@ INT_RETURN