The PCA9685 is an I2C-bus controlled 16-channel LED controller optimized for LCD
Red/Green/Blue/Amber (RGBA) color backlighting applications. Each LED output has its
own 12-bit resolution (4096 steps) fixed frequency individual PWM controller that operates
at a programmable frequency from a typical of 40 Hz to 1000 Hz with a duty cycle that is
adjustable from 0 % to 100 % to allow the LED to be set to a specific brightness value.
All outputs are set to the same PWM frequency.

PCA9685 also has a built-in oscillator for the PWM control.
However, the frequency used for PWM control in the PCA9685 is adjustable from
about 40 Hz to 1000 Hz as compared to the typical 97.6 kHz frequency of the
PCA9635. This allows the use of PCA9685 with external power supply controllers. All
bits are set at the same frequency.

The PCA9685 has 4096 steps (12-bit PWM)

1. 2P Terminal Block 5V input for PWM V+ & GPIO output pin 10 V+

2. J3  DA0 ~ DA7   U14 Port A    . J6 BA0 ~ BA7     U14 Port B

3. R62,R63,R64 ( for  U14 Address select A0,A1,A2)

4. U14 I2C 23017 -1  Port A,B 23017 Datasheet

5. U15  uln2803 

6. U3 PCA9685 (PWM Port 0 ~ 15) PCA9685 Data Sheet 

7. R10,R11,R12,R13,R14,R15( for U3 Address select A0,A1,A2,A3,A4,A5)

8. Red power-good V+ LED

9. 2  i2c device connect  J20 GND,+5V,SDA.SCL ( with level converter, safe for 5V device),

J21 GND 3V3,SDA,SCL  

plug in Raspberry Pi B2 with Servo motor& Step Motor

 in i2cdetect  you can found 2 device in system (21,41)

21 -  23017  41 - 9685

Support our Pi_Scratch software  

(1) Servo Motor control 

2 Servo in channel 0 & channel 7
Command "SE"+ "PWM (0-15)" + "a" +"angle" for Address 41

    se7a10   --> channel 7 servo move 10 angle  address 41

    se7a-10  --> channel 7 servo move -10 angle address 41

    se0a10   --> channel 0 servo move 10 angle  address 41

    se0a-10  --> channel 0 servo move -10 angle  address 41

(2) PWM  LED output demo

LED module (Blue, Green,Yellow,Red)

LED Scrolling  Command     PWMLED41S0E15D4True

PWMLED”Address” S[Start channel] E[End channel] D[Delay / Timing] [True/False]

Address 41, 42,43,44 

Start channel & End channel   0 ~ 15    16 channel

D   1,2,3,4,5    (1 ~ 100) Delay Timing

LED Brightness control Command 

PWMLED “Address” “B” “0 ~ 1000“ 

PWMLED41B1000

Stop command 

"PWMLED41STOP"