i2c interface with LED driver PCA9532


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  1. #1
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    Jul 2012
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    Default i2c interface with LED driver PCA9532

    Hi everybody,
    I am attempting to interface a PIC16F887 with a PCA9532 LED driver. I've read the PCA9532 datasheet http://www.nxp.com/documents/data_sheet/PCA9532.pdf and I am trying to follow the "Programming Example" on page 14. I am new to the i2c protocol and having problems receiving any response from the PCA9532. I have attached the programming example page and my test code. I will post my schematic shortly.

    Any help would be greatly appreciated. Thank you very much!

    Code:
    '****************************************************************
    '*  Name    : i2c comms test with led driver                    *
    '*  Author  : Cody Finden                                       *
    '*  Version : 1.0                                               *
    '*  Notes   : SOFTWARE FOR A 16F887 TO WRITE TO A LED DRIVER    *
    '*          : OVER THE I2C PROTOCOL                             *
    '****************************************************************
    
    
    #config
     __CONFIG _CONFIG1, _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _CPD_OFF & _BOR_ON & _IESO_ON & _FCMEN_ON & _LVP_OFF 
     __CONFIG _CONFIG2, _BOR40V & _WRT_OFF 
    #endconfig
    
    
    DEFINE OSC 20
    
    
    ANSEL =     %00000000
    ANSELH =    %00000000
    TRISA =     %00000000
    TRISB =     %00000000
    TRISC =     %00000000
    TRISD =     %00000000
    
    
    SDA         VAR PORTD.3
    SCL         VAR PORTD.2
    led         var portc.5
    addr        var byte
    
    
    INIT:
    PAUSE 400   'let hardware settle
    addr = $c0  'PCA9532 i2c address
    
    
    MAIN:
        
        I2CWRITE SDA,SCL,ADDR,[$12,$97,$80,$00,$40,$55,$FA,$00,$00]
        
        led = 1     'blink led for feedback
        PAUSE 250
        led = 0
        pause 250
    
    
    goto main
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  2. #2
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    Default Re: i2c interface with LED driver PCA9532

    I've drawn a schematic of my test setup for reference. Let me know if anything doesn't look right. Thanks!
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  3. #3
    Join Date
    Mar 2003
    Location
    Commerce Michigan USA
    Posts
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    Default Re: i2c interface with LED driver PCA9532

    I notice the led's are drawn backwards.... It will be kind of tough to get them to light....
    Dave Purola,
    N8NTA
    EN82fn

  4. #4
    Join Date
    Jul 2012
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    Default Re: i2c interface with LED driver PCA9532

    Lol, that's what happens when I draw a schematic in a hurry. Thanks for noticing. The leds are wired correctly on my breadboard though. I just can't get any response from the PCA9532. I've scoped the SDA and SCL pins and I can see the correct clock signal on SCL and various "data" on SDA, so I know that the PIC is outputting something. When I add the optional label argument to the i2cwrite function, the program constantly jumps to the label. Which means that I'm not receiving an acknowledge from the device. I've also tried adding "DEFINE I2C_SLOW 1" to my program because I'm running a 20MHz clock, but it did not help.

  5. #5
    Join Date
    Jul 2012
    Posts
    7

    Thumbs down Re: i2c interface with LED driver PCA9532

    Here is my new code and a shot of my oscilloscope to show the output. I can see that I'm not getting an acknowledge, but I do not know why.

    Code:
    '****************************************************************
    '*  Name    : i2c comms test with led driver                    *
    '*  Author  : Cody Finden                                       *
    '*  Version : 1.0                                               *
    '*  Notes   : SOFTWARE FOR A 16F887 TO WRITE TO A LED DRIVER    *
    '*          : OVER THE I2C PROTOCOL                             *
    '****************************************************************
    
    
    #config
     __CONFIG _CONFIG1, _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _CPD_OFF & _BOR_ON & _IESO_ON & _FCMEN_ON & _LVP_OFF 
     __CONFIG _CONFIG2, _BOR40V & _WRT_OFF 
    #endconfig
    
    
    DEFINE OSC 20
    
    
    ANSEL =     %00000000
    ANSELH =    %00000000
    TRISA =     %00000000
    TRISB =     %00000000
    TRISC =     %00000000
    TRISD =     %00000000
    
    
    SDA         VAR PORTD.3
    SCL         VAR PORTD.2
    led         var portc.5
    addr        var byte
    
    
    INIT:
    PAUSE 400   'let hardware settle
    
    
    'PCA9532 i2c address(7 bits + 1 bit for R/W) 
    'Slave address is 1100(A2)(A1)(A0) + (R/W)
    'In my setup A2 is pulled low, A1 pulled high, A0 pulled low
    addr = %11000100  
    
    
    MAIN:
        
    '    I2CWRITE SDA,SCL,ADDR,[$12,$97,$80,$00,$40,$55,$FA,$00,$00]
    
    
        I2CWRITE SDA,SCL,ADDR,$06,[$00]  'turn off led 0-3
        led = 1     'blink led for feedback
        PAUSE 250
        
        I2CWRITE SDA,SCL,ADDR,$06,[$55]  'turn on led 0-3 
        led = 0
        pause 250
    
    
    goto main
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  6. #6
    Join Date
    Oct 2011
    Posts
    50

    Default Re: i2c interface with LED driver PCA9532

    Two things I would try.
    1. Set SDA and SCL high at start
    2. The PCA9532 has a reset pin so after PAUSE 400 get the PIC to reset the PCA9532

    Phil

  7. #7
    Join Date
    Jul 2012
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    7

    Default Re: i2c interface with LED driver PCA9532

    Quote Originally Posted by Sherbrook View Post
    Two things I would try.
    1. Set SDA and SCL high at start
    2. The PCA9532 has a reset pin so after PAUSE 400 get the PIC to reset the PCA9532

    Phil
    Thanks for the reply! I added both of your ideas to my code, but I still cannot receive an acknowledge from the PCA9532. When I look at my scoped output and the datasheet, it looks like it should work with no problem... The address is correctly clocked out along with the R/W bit... there should be no problem. Anyways here's updated code: More advice will be greatly appreciated! Thanks.

    Code:
    '****************************************************************
    '*  Name    : i2c comms test with led driver                    *
    '*  Author  : Cody Finden                                       *
    '*  Version : 1.0                                               *
    '*  Notes   : SOFTWARE FOR A 16F887 TO WRITE TO A LED DRIVER    *
    '*          : OVER THE I2C PROTOCOL                             *
    '****************************************************************
    
    
    #config
     __CONFIG _CONFIG1, _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _CPD_OFF & _BOR_ON & _IESO_ON & _FCMEN_ON & _LVP_OFF 
     __CONFIG _CONFIG2, _BOR40V & _WRT_OFF 
    #endconfig
    
    
    DEFINE OSC 20                   '20MHz crystal
    'DEFINE I2C_SLOW 1 
    'DEFINE I2C_SCLOUT 1
    
    
    ANSEL =     %00000000           'no analog, all digital!
    ANSELH =    %00000000
    TRISA =     %00000000           'all ports output
    TRISB =     %00000000
    TRISC =     %00000000
    TRISD =     %00000000
    
    
    SDA         VAR PORTD.3         'i2c data line
    SCL         VAR PORTD.2         'i2c clock line
    led         var portc.5         'led for testing
    RST         VAR portc.6         'pca9532 reset pin (active low)
    addr        var byte            'pca9532 address storage var
    
    
    INIT:
    PAUSE 400   'let hardware settle
    RST = 0     'reset pca9532
    pause 10
    SDA = 1     'i2c pins high on startup
    SCL = 1
    RST = 1     'pca9532 on
    
    
    'PCA9532 i2c address(7 bits + 1 bit for R/W) 
    'Slave address is 1100(A2)(A1)(A0) + (R/(/W))
    'In my setup A2 is pulled low, A1 pulled low, A0 pulled low
    addr = %11000000  
    
    
    MAIN:
        
    '    I2CWRITE SDA,SCL,ADDR,[$12,$97,$80,$00,$40,$55,$FA,$00,$00]
    
    
        I2CWRITE SDA,SCL,ADDR,$06,[$00]  'turn off led 0-3
        led = 1     'blink led for feedback
        PAUSE 500
        
        I2CWRITE SDA,SCL,ADDR,$06,[$55]  'turn on led 0-3 
        led = 0
        pause 500
    
    
    goto main

  8. #8
    Join Date
    Jul 2012
    Posts
    7

    Default Re: i2c interface with LED driver PCA9532

    I got it working! The chip is in a SO24 package so I had to use a SMD to breadboard adapter, which was apparently faulty... Anyways there was no problem with my code, so it all works now! Thanks.

  9. #9
    Join Date
    Jul 2012
    Posts
    7

    Default Re: i2c interface with LED driver PCA9532

    Now that I have it working I will post a simple example of utilizing the PWM features on the PCA9532. Thanks. Also added an updated (and correct schematic) for anyone that wants to test out this 16 channel PWM LED driver.

    Code:
    '****************************************************************
    '*  Name    : i2c comms test with led driver                    *
    '*  Author  : Cody Finden                                       *
    '*  Version : 1.0                                               *
    '*  Notes   : SOFTWARE FOR A 16F887 TO CONTROL A PCA9532        *
    '*          : OVER THE I2C PROTOCOL                             *
    '****************************************************************
    
    
    #config
     __CONFIG _CONFIG1, _HS_OSC & _WDT_ON & _PWRTE_ON & _MCLRE_OFF & _CPD_OFF & _BOR_ON & _IESO_ON & _FCMEN_ON & _LVP_OFF 
     __CONFIG _CONFIG2, _BOR40V & _WRT_OFF 
    #endconfig
    
    
    'PCA9532 Control Registers
    psc0 con 000010   'frequency prescaler 0 (PERIOD = (PSC0 + 1) / 152)
    pwm0 con 000011   'PWM register 0        (0-255 PWM)
    psc1 con 000100   'frequency prescaler 1 (PERIOD = (PSC1 + 1) / 152)
    pwm1 con 000101   'PWM register 1        (0-255 PWM)
    ls0  con 000110   'LED0 to LED3 selector
    ls1  con 000111   'LED4 to LED7 selector
    ls2  con 001000   'LED8 to LED11 selector
    ls3  con 001001   'LED12 to LED15 selector
    
    
    DEFINE OSC 20                   '20MHz crystal
    'DEFINE I2C_SLOW 1 
    'DEFINE I2C_SCLOUT 1
    
    
    ANSEL =     000000           'no analog, all digital!
    ANSELH =    000000
    TRISA =     000000           'all ports output
    TRISB =     000000
    TRISC =     000000
    TRISD =     000000
    
    
    SDA         VAR PORTD.3         'i2c data line
    SCL         VAR PORTD.2         'i2c clock line
    led         var portc.5         'led for testing
    RST         VAR portc.6         'pca9532 reset pin (active low)
    addr        var byte            'pca9532 address storage var
    duty0       var byte
    duty1       var byte
    
    
    INIT:
    duty0 = 0
    duty1 = 255
    PAUSE 400   'let hardware settle
    RST = 0     'reset pca9532
    pause 10
    SDA = 1     'i2c pins high on startup
    SCL = 1
    RST = 1     'pca9532 on
    
    
    'PCA9532 i2c address(7 bits + 1 bit for R/W) 
    'Slave address is 1100(A2)(A1)(A0) + (R/(/W))
    'In my setup A2 is pulled low, A1 pulled low, A0 pulled low
    addr = 000000  
    
    
    MAIN:
        
        I2CWRITE SDA,SCL,ADDR,psc0,[$00]  'set both pwm prescalers to max pwm freq
        I2CWRITE SDA,SCL,ADDR,psc1,[$00]
        
        duty0 = duty0 + 1                        'increment duty0 for pwm0
        duty1 = duty1 - 1                        'decrement duty1 for pwm1
        
        I2CWRITE SDA,SCL,ADDR,pwm0,[duty0]       'set duty cycle on pwm0
        I2CWRITE SDA,SCL,ADDR,pwm1,[duty1]       'set duty cycle on pwm1
        
        I2CWRITE SDA,SCL,ADDR,ls0,[101010]    'enable led0-3 with pwm0
        I2CWRITE SDA,SCL,ADDR,ls1,[111111]    'enable led4-7 with pwm1
        
        if duty0=255 then 'restart count on overflow
            duty0=0
        endif
        if duty1=0 then 'restart count on overflow
            duty1=255
        endif
        
        pause 5     'delay for viewing pleasure
        
    '    led = 1     'blink led for feedback
    '    PAUSE 50
    '    led = 0
    '    pause 50
    
    
    goto main
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    Last edited by koodiifin; - 13th July 2012 at 20:10. Reason: added schematic

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