PCA9685PW Coding

I'm hoping to use a PCA9685PW (16 channel PWM LED driver chip) to control some aquarium light I've made. Basically I want to use 4 channels of the chip so I can independently turn on and dim 4 sets of LEDS.

I've got a PCA9685PW chip on a breakout board, opened up the datasheet ( http://www.nxp.com/documents/data_sheet/PCA9685.pdf ) and it went completely over my head.. Can someone advise on the basics, like how to set the address (I think its set by grounding / supplying 6 pins ?).

In PicBASIC PRO I use the following to read the hours minutes and seconds from the DS1307 RTC chip

Code:

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I2CREAD SDApin,SCLpin,$D0,$00,[RTCSec,RTCMin,RTCHour]

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The first part is straight forward, and I guess I need to use a different address than $D0,$00 so as not to clash with the RTC chip, but what would I need to do to send the PWM variable to the correct LED channel etc on the PCA chip. I currently use two variables B_PWM and W_PWM which currently has a value of between 0 and 254. It's simple enough to change that to from a byte to word variable as the PCA chip has 4095 steps, but other than that I'm lost ! Any help with interpreting the datasheet would be welcolm

if you connect a5 to vcc and a4-a0 to gnd the slave address should be $C0
a quick google of this device found 0 results for example code for any language whatsoever.
(might be natures way of saying "good luck with that")
good luck with that

Well for reference this works. Its fairly easy to modify the code to use a variables for the value for the pulse width which should be 0 - 4095

Code:

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i2cControl var BYTE

i2cAddress var BYTE
pcaAddress var BYTE
pcaAddress = $40

i2cAddress = pcaAddress << 1

;Reset
;PCA9685_MODE1 0x0
i2cControl = 0
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[0]

;Set PWM to 500Hz
;Prescaler = 11
;Calculate prescaler by:
;floor((((25000000/4096)/requiredFreqInHertz)-1)+0.5)
;For lack of float support or floor function the value can be calculated and then hard-coded

;Get old mode
oldMode var BYTE
;PCA9685_MODE1 0x0
i2cControl = 0
I2CREAD SDApin,SCLpin,i2cAddress,i2cControl,[oldMode]
newMode var BYTE
;MODE1 Sleep
newMode = (oldMode & $7F) | $10
;Set MODE1 Sleep
;PCA9685_MODE1 0x0
i2cControl = 0
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[newMode]
;Set Prescaler
;PCA9685_PRESCALE $FE
;Prescaler is 11
i2cControl = $FE
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[11]
;Set old mode
;PCA9685_MODE1 0x0
i2cControl = 0
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[oldMode]
Pause 5
;Set MODE1 AutoIncrementOn
;PCA9685_MODE1 0x0
i2cControl = 0
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[oldMode | $A1]


;;Set a PWM channel
;;
pcaChannel var BYTE
pcaPwmValue var BYTE

pcaChannel = 0
pcaPwmValue = 4095
;LED0_ON_L 0x6
i2cControl = $6 + 4*pcaChannel
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[0,0,pcaPwmValue,pcaPwmValue >> 8]

pcaChannel = 1
pcaPwmValue = 1024
;LED0_ON_L 0x6
i2cControl = $6 + 4*pcaChannel
I2CWRITE SDApin,SCLpin,i2cAddress,i2cControl,[0,0,pcaPwmValue,pcaPwmValue >> 8]

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