Using PWM on a HERO?

So, my team is working on a robot using the CTR Hero. We wanted to use four Victor SPs, but I don’t know how to wire it. I can’t figure out how many PWM devices the Hero supports. In the user guide it says it supports 3 on page 10, pins 4, 6, 7, 8, and 9 on page 52, and that there are total of 5 on page 75.

I’m more of better at programing than electrical, so I need help. Could we let all the Victors share a ground, and the other cable goes to pins 4, 6, 7, and 8 respectively? Thanks for your help!

The information in section 9.4.4 of the HERO User’s Guide (page 58 in the most recent revision) is correct - there are 5 available PWM pins on the HERO.

Table 2.2 on page 10 (and the corresponding chart on page 9) is referencing the official Gadgeteer specification from Microsoft, which dictates that pins 7, 8, and 9 on a ‘P’ port must be available for PWM use. (see here)

Our IO configuration on the HERO, however, allows us to have 2 extra PWM pins (pins 4 and 6). Since we felt that having more than the 3 pins called out by the spec could be useful for those that still use PWM motor controllers, we decided to implement the extra 2 pins that were available to us, bringing our total up to 5.

I realize this could be a little confusing, so we’ll try to make a note in the next release of the manual to prevent the confusion.

You’re correct in your thinking about the wiring configuration. The ground wires for the Victor SPs can be commonized to the ground pin on Port 3, and then the signal wires can be connected to the individual PWM pins.

As another note, if you need to conserve PWM pins you can wire the signals for motor controllers with mechanically linked motors to the same PWM port.
IE, if you have a drive train where two motors are driving a single gearbox, the signals for these motor controllers can be controlled from a single PWM port.

Thanks for you help, our robot is up and running now! :smiley: