PCA9685 driver for Analog Outputs


The PCA9685 driver for Analog Outputs is used to modulate the pulse width of a channel on a PWM extender connected to the Builder Base. This driver cannot alter the frequency, it is pure PWM.

Driver Parameters

The PCA9685 driver for Analog Outputs has two parameters that have to be configured: 

I2C Address

This is the address the device is being referenced by on the I2C bus. The base I2C address is

  • Binary: 1000000

  • Hex: 0x40

The last 6 bits are altered by the address A0-A5 pins:

A5 A4 A3 A2 A1 A0

1 0 0 0 0 0 0

So as an example if we set all pins to 1 we have

  • Binary: 1111111

  • Hex: 0x7f

The device has a “can all“ address, which is 0x70, so the I2C scan is going to report two addresses usually: the one selected with the A pins and 0x70.

More information about addressing can be found in the datasheet

Also for translation help see the Binary to Hex converter here


This is the channel on the PCA9685 modulating the pulse width; enter a number between 0-15 to select the channel you want to modulate. The Quantum System supports 8-bit (0-255) PWM.


The chip can be found in either a DIP socket adapter or in popular development boards as shown below

Development Board


Chip Pinout


Channel 0 is connected to an LED directly. The chip is connected to address 0x40 of the I2C bus because none of the connectable addresses is set to HIGH.



Used Pins

Used Pins


Used Pins



The voltage level for the assembly


The ground potential for the assembly


The I2C data line


The I2C clock line

How to write an App

Navigate to the App Builder and create a new application. You can find the “Analog Out” code object under the “Hardware” Tab in the object drop down menu on the left, or you can also use the search bar.



Drag the “Analog Out” Object onto the canvas.


 Next, locate the “Slider Analog” object under the “Interface” tab and drag it onto the canvas.



Finally, connect the value port on the Analog Slider to the value port on the Analog Out object.

How to create a firmware

Navigate to the Firmware Builder and create a new Firmware file.



Click the “+Add Hardware” button which will open a modal window. Scroll down in the list to find the “Generic” section and select the “Analog Out” hardware option.

Give your device a name and click “Add Device”





Next, select the “PCA9685” driver under the driver dropdown menu.


Next, set the I2C Address and the channel

For this example we will select:

  • I2C Address: 0x40

  • Channel: 0





You may now save your firmware file and upload it to one of your Builder Bases





Supported Hardware

  • PWM

  • Buzzer