This is a bit out of topic and I Hope this doesn't seem too naive, but I am having a lot of trouble driving a TB6612FNG based shield with a TLC5940 PWM expander:
I've had this project going where I have been driving a series of dc motors with fishing line. if you are interested here is the project: www.vorticose.ocular-witness.com
Up until this point, I have been using an arduino mega with about 4 motor driver sheilds:
http://www.robotshop.com/ca/productinfo.aspx?pc=RB-Dfr-58&lang=en-US
http://www.robotshop.com/ca/content/PDF/manual-dri0009.pdf
this worked fine using the PWM pins from the arduino but was limiting. (I was limited to 8 motors with this)
I am now expanding this scenario to 30 motors using:
this motor driver: SparkFun Motor Driver - Dual TB6612FNG (1A) - ROB-14451 - SparkFun Electronics that is based on the TB6612FNG chip.
and to expand the number of PWM pins using this shield: practicalmaker.com - This website is for sale! - practicalmaker Resources and Information.
that is based on the TLC5940 16-channel LED Driver
The motor driver works fine when hooked up to an arduino with PWM and digital outs for High / low directional instructions.
But things get messy when I use the LED driver for PWM.
To begin with, the PWM jumpers have BOTH a ground and a power. Which for the PWM for arduino there is only one PWM signal.
So I send the signals to the motor driver from the arduino using digital outs for the motor state to the motor driver. And a PWM signal through the PWM sheild. The negative I hook up to the common ground. This overheats the motor driver chip and simply doesn't work. I am not sure what to do with the ground from the PWM sheild jumper.
My first thought is that the arduino and the TLC5940 have different kinds of PWM.
Really stuck with an impending deadline: any advice would be really appreciated.