16-Channel 12-bit PWM/Servo Driver

[jackjameshoward]

Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface - PCA9685 (ID: 815)

I'm sure its possible to wire this product up to a few L293D chips, right?
Just because this product has 'servo driver' in the title doesn't mean that i cant use it as just a PWM driver.
Please let me know if im correct or not.

I know adafruit sell motor shields with PWM. I'm just looking to do things the hard way

[adafruit_support_bill]

Yes. Typically, you would drive the direction control pins with normal digital pins, then send a PWM signal to the Enable pin for speed control.

[jackjameshoward]

My aim is to control steppers using only two pins. So i can free up pins for other uses. The same as your latest motor shield.

You say 'typically ' does this mean i have the wrong idea slightly, what else would i need to make this work the way i want?

[adafruit_support_bill]

My aim is to control steppers using only two pins.

My comment was based on driving a DC motor. Steppers are a little more involved.
Although there are integrated stepper drivers with 2-pin control, the L293D is a much more basic chip. It consists of 4 half-bridges which are controlled separately. You would need some additional circuitry to achieve the 2-pin control you are looking for. http://www.adafruit.com/datasheets/l293d.pdf

In the case of the motor shield, we use a 74HC595 latch chip to manage the 4 inputs and a PWM pin to pulse the enable input for each full-bridge pair.

[jackjameshoward]

Superb,
That bit of information was the missing piece of my puzzle.
After a quick google, it turns out the 74HC595 latch chip is a neat little chip to have

[jackjameshoward]

Can i perhaps use ID: 292 for this purpose?
Also how many PWM pins do you need to control multiple full-bridge pairs individually? Is it one pin per full-bridge pair or can I string multiple pairs to a single pin

[adafruit_support_bill]

Can i perhaps use ID: 292 for this purpose?

The board itself is designed for driving displays, but at it's heart is an i2c port expander. You could use it to control an H-bridge - but it does not do PWM.

There are any number of ways to design a motor shield. Perhaps the best place to start is by reviewing some of the existing designs:
https://github.com/adafruit/Adafruit-Mo ... or-Arduino
http://arduino.cc/en/uploads/Main/ardui ... d_Rev3.zip
http://ruggedcircuits.com/AD030/ad030_E.pdf