the spingarage blog

The FroBoard design is now available for free- but this won't do you much good if you don't know what a FroBoard is. So here is the original text from the product page!

The FroBoard is a program-it-yourself development board designed to take the black magic out of brushless DC motor control. We’ve taken the time to engineer all the nitty gritty circuit board stuff, so you can focus on the ultimate goal: making stuff spin.

The FroBoard includes all of the hardware necessary to drive the power section of a brushless motor controller. A functional controller can be built with nothing more than a FroBoard, 6 MOSFETs or IGBTs, and a little ingenuity. Here’s what’s on the board:

• A PIC18F4431 processor, clocked at 20 MHz. Check out the datasheet, it’s a beast.
• 3 FAN7390 half-bridge drivers, capable of driving everything from IRF510s all the way up to big IGBT modules. All wired up to the power-control PWM module in the PIC. They’re also fully isolated through optocouplers and isolated power supplies, so they’re suitable for high voltage systems requiring isolation.
• 6 logic level PWM outputs, configurable as complementary PWMs, for driving small transistor power sections or for debugging with an oscilloscope.
• A MAX232 chip wired up to the EUSART of the PIC for easy interfacing to pretty much anything (a computer, for instance) through the on-board DB-9 connector.
• 18 programmable I/Os (including 9 which are configurable as analog inputs) wired up to 3-pin headers for easy access.
• Two relays hooked up to the PIC. We use ‘em to control big contactors (through a secondary, larger relay) in EV drive systems.
• Two debugging LEDs wired up to the PIC. They’re blue, which is awesome.
• A standard 6-pin programming interface for programming with any standard PIC programmer.
• A voltage regulator to allow use with 9-18V DC power supplies.

The PIC processor used on the FroBoard is easily programmed in assembler or PICBASIC. While some programming experience is necessary, there are lots of resources available to help you out.

To build a brushless motor controller of any size using the FroBoard, you’ll just need to build or purchase a power section (this basically consists of six or more transistors, MOSFETs, or IGBTs), wire it up to the outputs of the FroBoard, and write some code to commutate the motor. Simple code examples and power section schematics are provided in the manual to get you started.

We’ve used the FroBoard for just about everything, including a brushless motor controller suitable for full-sized electric vehicles using 300A IGBT modules. We’ve also used it to control small robots through a serial interface on a computer. The great thing about the FroBoard is that it allows you to mix higher-level interface and logic functions with low-level brushless motor control algorithms, so you don’t have to use a secondary processor to control peripherals like contactors or human interfaces.

Download the PCB layout, schematic, assembly details, and user's guide here if you're interested!

//AGA