Hey guys,

I want to expand my PWM pins on my Arduino GIGA R1 with the PCA9685-module.
How do I draw this schematic and what do I need to look out for?

Thanks Already!

Greets,

Rens

 

I think the PCA9685 has PWMs inside and does not need to use the PWM from the Arduino.

 

I think the connection should be like this:

Arduino GIGA R1	PCA9685 Module
+5V	VCC
GND	GND
SCL	SCL
SDA	SDA

 

Hey guys,

Thanks for the advice,

I found this from the Adafruit PWM-expantion Module:


Looks correct to me, only I don't understand the Analog connections? Do I need to connect the analog connections to my Arduino?

 

There are no analog connections. A5-A0 are address select inputs.

 

There are no analog connections. A5-A0 are address select inputs.

Okay, so where do I connect them to?

 

Okay, so where do I connect them to?

You wire them directly to Vcc and GND to whatever slave address you choose. The corresponding slave address is transmitted in the I2C data.

 

You wire them directly to Vcc and GND to whatever slave address you choose. The corresponding slave address is transmitted in the I2C data.

Hi, I've been doing some reading in the datasheet of the PCA9685, and i get what you mean. So I either connect a analog pin to VCC or GND to form a unique combination to get form 62 different adresses.

How can i connect then multiple modules at one I2C connection, just connect it al to that connection?
Right now I come this far:

 

A5-A0 are slave device address pins. You can have as many as 62 slave devices.
On a generic production board, A5-A0 can be wired to DIP switches or PCB jumpers so that each board can be configured for a specific slave address.

Each slave will now have a unique physical address. The I2C data command includes a slave address so that only the intended slave will act on the received command.

 

A5-A0 are slave device address pins. You can have as many as 62 slave devices.
On a generic production board, A5-A0 can be wired to DIP switches or PCB jumpers so that each board can be configured for a specific slave address.

Each slave will now have a unique physical address. The I2C data command includes a slave address so that only the intended slave will act on the received command.

What are DIP switches?
And how can I make like 4 PCA9685 modules in the bus, how do i connect that?
By the way, I don't need pull up resistors on SDA and SCL right in my schematic?

 

DIP stands for Dual In-line Package. They fit on 0.3" width IC spacing on a PCB.

Examples of DIP switches


Get I2C communications working firstly with one PCA9685 before moving on to multiple devices.

 

DIP stands for Dual In-line Package. They fit on 0.3" width IC spacing on a PCB.

Examples of DIP switches
View attachment 327080

Get I2C communications working firstly with one PCA9685 before moving on to multiple devices.

Okay thanks, how do I calculate the Pull-up Resistors, and are they needed in my Schematic?

 

Okay thanks, how do I calculate the Pull-up Resistors, and are they needed in my Schematic?

Pull-up resistor value is not critical. 10k - 100kΩ will work for CMOS inputs.

 

Pull-up resistor value is not critical. 10k - 100kΩ will work for CMOS inputs.

Can i just connect the Pull-up resistors to my powersupply (so the arduino 3,3V)
And do I need pull-up resistors for every extra PCA9685 module?

I've got this schematic so far, how does it look:

 

Can i just connect the Pull-up resistors to my powersupply (so the arduino 3,3V)
And do I need pull-up resistors for every extra PCA9685 module?

I've got this schematic so far, how does it look:
View attachment 327083

Sorry, when you asked about pull-up resistors I thought that you were referring to the A5-A0 address select inputs.
For I2C SDA and SCL signals, you need to check for the recommended values. I don't have time to check this now.
No, you do not need pull-ups at every I2C device. I2C is a network and it requires the proper resistor for the whole network.

 

For I2C networks, the value of the pull-up resistor will depend on a number of factors, primarily, clock frequency, line capacitance, cable length, number of devices, supply voltage, power consumption. Typical resistance values range from 1kΩ to 10kΩ.

This article gives a specific example and arrives at a value of 1kΩ.

https://www.ti.com/lit/an/slva689/slva689.pdf

 

For I2C networks, the value of the pull-up resistor will depend on a number of factors, primarily, clock frequency, line capacitance, cable length, number of devices, supply voltage, power consumption. Typical resistance values range from 1kΩ to 10kΩ.

This article gives a specific example and arrives at a value of 1kΩ.

https://www.ti.com/lit/an/slva689/slva689.pdf

Thanks man, I think indeed a simple 10K ohm resistor will do. Do I need a level shifter when using the arduino Giga and the shown below chip with the setup?: